nrc: home page · 'ttachments a. 'resume - richard b. hubbard. b. c. d. e'....

'TTACHMENTS

A. 'Resume - Richard B. Hubbard.

B.

C.

D.

E'.

Biography - Eli Silver.Biography - Clarence A. Hall, ~ Jr.Resume - Stephan Alan Graham.

Curriculum Vitae — William R. Dickinson.

G.

H.

K.

"The San Gregorio-Hosgri Fault Zone: An Overview," -'li Silver."Evidence for 115 Kilometers of Right Slip on the San 'Gregorio-Hosgri Fault Trend," S.A. Graham and W. R. Dickinson."San Simeon-Hosgri Fault System, Coastal California: Economicand Environmental implications," C.A. Hall, .Jr."Origin and Development of the Lompoc-S'anta Maria Pull-ApartBasin and its Relation to the 'San Simeon-Hosgri Strike-SlipFault, Western California," C.A. Hall, Jr."Marine Geology and Tectonic History of the Central CaliforniaContinental Margin," E.A. Silver, D.S. McCulloch, and J .R. Curry.

"Application of Linear Statistical Models of Earthquake MagnitudeVersus Fault Length in Estimating Maximum Expectable Earthquakes,"Robert K. Mark.

L. USGS Open File Report 77-614, "Regression Analysis of EarthquakeMagnitude and Surface Fault Length Using the 1970 Data of Bonillaand Buchanan," R.K. Mark and M.G. Bonilla.

M.

N.

O.

Biography - James N. Brune.

Curriculum Vitae - J. Enrique Luco,

Curriculum Vitae - Mihailo D. Trifunac.P.

R.

"Review of the 'Seismic Evaluation for Postulated 7.5M HosgriEarthquake, Units 1 and 2, Diablo Canyon Site,'" J. Enrique Luco.

"Comments on Seismic Design Levels for Diablo Canyon Site inCalifornia," M. D. Trifunac.USGS Open File Report 78-509, "Estimation of Ground MotionParameters," D. M. Boore, A.A. Oliver, R.A. Page, and W.B. Joyner.

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ATTACHE Z A

Richard B. Hubbard366 California AvenueSuite 7Palo Alto, CA 94306(415) 329-0474

EXPERIENCE

9/76 - Present

Partner - MHB Technical Associates, Palo Alto, California.'ounderan managing partner o tec nica consu ting irm. Specialists, in:independent energy assessments for government agencies, particularytechnical and economic evaluation of nuclear power facilities. Con-sultant in this. capacity to Illinois Attorney General; Suffolk County,New York; Schweinfurt, Germany; Governor of Colorado; and SwedishEnergy Commission. Also provided studies and testimony for variouspublic interest groups including Center for Law In The Public Interest,Los Angeles; Public Law Utility Group, Baton Rouge, Louisiana; andUnion of Concerned Scientists, Cambridge,"Massachusetts. Providedtestimony to U.S. Senate/House Joint Committee on Atomic Energy, U.S.House Committee on Interior and Insular Affairs, California Assembly,Land Use, and Energy Committee, Advisory Committee on Reactor Safe-guards, and Atomic Safety and Licensing Board. Performed comprehensiverisk analysis of the accident probabilities and consequences at theBarseback Nuclear Plant for the Swedish Energy Commission and edited,as well as contributed to, the Union of Concerned Scientist's technicalreview of the NRC's Reactor Safety Study (WASH-1400).

2/76 - 9/76

Consultant, Pro'ect Survival, Palo Alto, California. Volunteer workon Nuc ear Sareguar s Initiative campaigns xn Ca i ornia, Oregon,Washington, Arizona, and Colorado. Numerous presentations- on nuclearpower and alternative energy options to civic, government, and collegegroups. Also resource person for public service presentations onradio and television.

5/75 - 1/76

%fang er - Qualit Assurance Section Nuclear Energy Control andnstrumentation Deoartment, Genera E ectrz.c Comoanv, San Jose,a x orna.a. eport to t e Department enera Manager. Deve op and~pqh'yyd,yd,hd,dq'ph'h

that products produced by the Department meet quality requirementsas defined in NRC regulation 10 CFR 50, Appendix B, ASME Boiler andPressure Vessel Code, customer contracts, and GE Corporate policiesand procedures. Product areas include radiation sensors, reactor

t tvessel internals, fuel handling and servicing tools, nuclear plantcontxol and protection instrumentation systems, and nuclear steamsupply and Balance of Plant contxol room panels.Responsibile for approximately 45 exempt personnel, 22 non-exemptpexsonnel, and 129 hourly personnel with an expense budget of nearly4 million dollars and and equipment investment budget of approxi-mately 1.2 million dollars.

11/71 - 5/75 /Mana er - ualit Assurance Subsection, Manufacturing Section of

tomic ower auzoment De axtment, enera ectrz.c ComDan, 'anJose, Ca izoxnia. Report to the Manager or Manu acturing. Sameunctzona an product- responsiblities as in Engagement ><1, except

at a lower oxganizational =report level. Developed a quality systemwhich received NRC certification in 1975. The system was also suc-cessfully surveyed for ASME "N" and "NPT" symbol authorization in1972 and 1975, plus ASME "U" and ".S" symbol authorizations in 1975.Responsible for from 23 to 39 exempt personnel, 7 to 14 non-exemptpersonnel, and 53 to 97 hourly personnel.

,3/70 - 11/71

Mana er - A plication En ineerin Subsection, Nuclear Instrumentatione artment, enexa r. ectrxc Comoan , San Jose, Ca i ornia. Respon-

se e or t e post oraer tecnnxca znter ace wxt arc detect engineersand power plant owners to define and schedule the instrumentationand control systems for the Nuclear Steam Supply and Balance. ofPlant portion of nuclear power generating stations. Responsibilitiesincluded preparation of the plant instrument list with approximatelocation, review of interface drawings to define functional designrequirements, and release of functional requirements for detailedequipment designs. Personnel supervised included 17 engineers and5 non-exempt personnel.

12/69 - 3/70

Chairman - E uivment Room Task Force, Nuclear Instrumentation Depart-ment, Genera E ectrx,c Com an , ban ose, a x orna.a. esponsz. e

or a specia tas force reporting to tne Department General Managerto define methods to improve the quality and reduce the installationtime and cost" of nuclear power plant control rooms. Study resultedin the conception of a factory-fabricated contxol room consisting ofsignal conditioning and operatox control panels mounted on modularfloor sections which are completely assembled in the factory andthoroughly tested for proper operation of interacting devices.Personnel supervised include 10 exempt personne'l.

I'2/65- 12/69

Mana er — Pro osal En ineerin Subsection, Nuclear Instrumentatione axtment, Genera E ectrxc Comoany, San Jose, Ca x. ornza. Respon-

se e or t e app ication o instxumentatxon systems or nuclearpower reactors during the proposal and pxe-order"period., Respon-sible for technical review of bid specifications, preparation of

technical bid clarifications and exceptions, definition of materiallist for cost estimating, and the "as sold" review of contxactsprior to turnover to Application Engineering. Personnel supervisedvaried from 2 to 9 engineers.

8/64 - 12/65

Sales En ineer, Nuclear Electronics Business Section of Atomicower uivment Oeoartment, enera E ectrx.c om an, an aose,

Ca i ornia. Responsi e for t e i review, contract negotiation,y d ~ C * 1

power plants, test reactors, and radiation hot cells. Also respon-sible for industrial sales of radiation sensing systems for measure-ment of chemical properties, level, and density.

10/61 - 8/64

A lication En ineer, Low Volta e Switch ear Department, GeneralE ectric Cpm@an , P i a e xa, Penns vania. Responsi e or theapp >cation and design o advance iode an silicon controlledrectifier constant voltage DC power systems and variable voltagedc power systems for industrial applications. Designed, followedmanufacturing and"personallly tested in advanced SCR power supplyfor product introduction at the Iron and Steel Show. ProjectEngineer for a dc power system for an aluminum pot line sold toAnaconda beginning at the 161XV switchyard and encompassing allthe equipment to.,convert the power to 700 volts dc at 160,000amperes.

9/60 — 10/61

GE Rotational Tzainin P~to tam

Four 3-month assignments on the GE Rotational Training Program forcollege technical graduates as follows:

a. Installation and Service En . — Detroit, Michigan. Installationan startup testing ot t e wor s argest automated hot stripsteel mill.

b. Tester - Industr Control - Roanoke, Vir inia. Factory, testingo contro pane s or contro o stee , paper,'ulp, and utilitymills and power plants.

c. En ineer - Li ht Milita Electronics - Johnson Cit, New York.eszgn o groun support equipment or testing t e auto px, ots

on the F-105.

d. 'ales En~ineer — Morrison, Illinois. Sale of appliance controlsinc u xng range timers an rezrxgerator cold controls.

A 3

EDUCATION

Bachelor of Science Electrical Engineering, University of Arizona,1960.

Master of Business Administration, University of Santa Clara, 1969.

PROFESSTONAL AFFILIATION

Registered Quality Engineer, License No. QU805, State of California.Member of Subcommittee 8 of the Nuclear- Power Engineering Committeeof the IEEE Power Engineering Society responsible for the preparationand xevision of the following 4 national Q.A. Standards:

a ~ IEEE 498 (ANSI .N45.2. 16), Supplementary Requirements forthe Calibration and Control of Measuring and Test Equipmentused in the construction and maintenance of Nuclear PowerGenerating Stations.

b. IEEE 336 (ANSI N45.2.4), Installation, Inspection, and TestingRequirements for Instrumentation and Electric Equipment duringthe construction of Nuclear Power Generating Stations.

c. IEEE P467 (ANSI N45.2.14), Quality Assurance Program Require-ments for the Design and Manufacture of Class IE Instrumen-tation and Electric Equipment for Nuclear Power GeneratingStations.

d. IEEE Draft, Requirements for the Procurement and Storage ofClass IE Equipment Replacement Parts.

PERSONAL DATA

Birth Date: 7/08/37Married; three childrenHealth: Excellent

" PUBLICATIONS AND TESTIMONY

1. Swedish Reactor Safe Stud: Barseback Risk Assessment, 1KBTec nical Associates, January 1 7 Pu ishe by Swe sh Depart-ment of Industry as Document DSI 1978:1) .

2. The Risks of Nuclear Power Reactors: A Review of the NRC ReactorSa et Stu v MASH- w, Ken a, et a, e ate y R. B. Hu bardan . C. Manor ox Union of Concerned Scientists, August 1977.

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3. Testimony of R. B. Hubbard to Advisory Committee on Reactorgafeguards, August.12, 1977, Washington, DC, entitled, RiskUncertaint Due to Deficiencies in Diablo Can on Qualit

ssurance Pro ram an Far. ure to m ement Current NRC

Pr actices.

Testimony R. B. Hubbard to United States House of Representatives,Subcommittee on Energy and the Environment, June 30, 1977,Washington, DC, entitled, Effectiveness of NRC Re ulationsModifications to Diablo Can on Nuc ear Unx.ts.

5. Testimony of K. B. Hubbard and G. C. Minor, Judicial HearingsRegarding Grafenrheinfeld Nuclear Plant, March 16 6 17, 1977,Wurzburg, Germany.

6. Testimony of R. B. Hubbard and G. C. Minor before CaliforniaState Senate Committee on Public Utilities, Transit, and Energy,Sacramento, California, March 23, 1976.

~ 7. Testimony of R. B. Hubbard, D. G. Bridenbaugh, and G. C. Minorto the California State Assembly Committee on Resources, LandUse, and Energy, Sacramento, California, March 8, 1976.

8. Testimony of R. B. Hubbard, D. G. Bridenbaugh, and G. C. Minor.before the United States Congress, Joint Committee on AtomicEnergy, February 18; 1976, Washington, DC. (Published by Unionof Concerned Scientists, Cambridge, Massachusetts.) Excerptsfrom testimony published in uote Without Comment, Chemtech,May, 1976.

9. ualitv Assurance: Providin It, Provin It, R. B. Hubbard,Power, Hay, 197

10. In-Core S stem Provides Continuous Flux Map of Reactor Cores,R. B. Hu bard an C. E. Foreman, Power, iVovem er, 1 7.

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AUG1B $78

ATTACHMENT B

Biographical Data

,Eli SilverAssociate Professor, Earth SciencesUniversity of California, Santa Cruz

Born — June 3, 1942

B.A. — Geology, University of California, Berkeley, 1964

Ph.D. — Oceanography, Scripps Institution of Oceanography,1969

Post-Graduate Research Oceanographer, Scripps Institutionof 'Oceanography, 1969-1970

Geologist, U. S. Geological Survey, 1970-1974

Assistant Professor, Earth Sciences, University ofCalifornia, Santa Cruz, 1974-75

Associate Professor, Earth Sciences, University ofCalifornia, Santa Cruz, 1975-present

Chief scientist and/or cruise leader on numerous cruisesof Scripps Institution of Oceanography and theU. S. Geological Survey

Fellow: Geological Society of America

Member: American Geophysical Union, Society of ExplorationGeophysicists, Seismological Society of America, AAAS

Selected Publications

Moore, G. W., and Silver, E. A., 1968, Geology of t:heKlamath River Delta, California: U. S. Geol. SurveyProf. Paper 600-C, p. C144-C148.

Moore, G. N., and Silver, E. A., 1968, Gold distributionon the sea floor off the Klamath Mountains, California:U. S. Geol. Survey Circ. 605, 9 p.

Silver, E. A., 1969, Late Cenozoic underthrusting of thecontinental margin of northernmost California:

'Science,- v. 166, p. 1265-1266.

Silver, E. A., 1971, Transitional tectonics and Late Cenozoicstructure of the continental margin off northernmostCalifornia: Geol. Soc. America Bull., v. 82, no. 1,p. 1-22.

Silver, E. A., 1971, Tectonics of the Mendocino TripleJunction: Geol. Soc. America Bull., v. 82, p. 2965-2978.

Silver, E. A., Curray, J. R., and Cooper, A. K., 1971,Tectonic development of the continental margin offcentral Calif.: Geological'Society of Sacramento,Annual Field Trip Guidebook, p. 1-10.

Silver, E. A., 1971, Small plate tectonics of the north-eastern Pacific: Geol. Soc. America Bull., v. 82,p. 3491-3496.

Silver, E. A., and others, 1972, USGS-IDOE Leg 4,Venezuelan. borderland: Geo times, v. 17, p. 19-21.

Silver, E. A., 1972, Subduction zones: Note relevant topresent-day problems of waste disposal: Letter,Nature, v. 239, p. 330-331.

Silver, E. A., 1972, Pleistocene tectonic accretion ofthe continental slope off Nashington: Mar. Geol.,v 13 I p 239 249

Jackson, E. D., Silver, E. A., and Dalrymple, G. B., 1972,Hawaiian-Emporer chain and its relation to CenozoicCircumpacific tectonics: Geol. Soc. America Bull.,v. 83, p. 601-618.

Dalrymple, G ~ B., Silver, E. A., and Jackson, E. D., 1973,Origin of the Hawaiian Islands: American Scientist,v 61 I no. 3, p. 294-308 ~

Silver, E. A., von Heune, R., Crouch, J. K., 1974, Tectonicsignificance of the Kodiak-Bowie seamount, chain,Northeastern Pacific: Geology, v. 2, p. 147-150.

Silver, E. A., 1974, Geometrical principles of plate tec-tonics: in San Joaquin Geological, Soc. Short Course,Geological Interpretations from global tectonics withapplications for Calif. geology and petroleum exploration,N. R. Dickinson, ed., p. 1-1 to 1-3.

Silver, E. A., 1974, Basin development along translationalcontinental margins: in San Joaquin Geological Soc.Short Course, Geological interpretations from globaltectonics with applications for Calif. geology andpetroleum exploration, N. R. Dickinson, ed., p. 6-1 to6-5.

B-2

Silver, E. A., 1974, Evolution of the San Andreas faultsystem: in San Joaquin Geological Soc. Short Course,Geological interpretations from global tectonicswith applications for Calif. geology and petroleumexploration, W. R. Dickinson, ed., p. 12-1 to 12-5.

Silver, E. A , 1974, Detailed near-bottom geophysical profileacross the continental slope off northern California:U.S. Geol. Survey Jour. of Research, v. 2, p. 563-567.

Silver, E. A., Case, J. E., and MacGillavry, H. J., 1975,Geophysical study of the Venezuelan borderland: Geol.Soc. America Bull., v. 86, p. 213-226.

Silver, E. A., 1975, Collision events in orogenesis (abs):13th Pacific Science Congress, Vancouver, Canada.

Silver, E. A., 1975, Collision events in orogenesis: EOS,v. 56, p. 1066.

Silver, E. A. and Moore, J. C., 1976, A geophysical studyof the Molucca Sea collision zone, Indonesia (abstract):EOS, Trans. AGU, v. 57, p. 1003.

Silver, E. A.', 1977. The Sula spur enigma (abstract): Geol.Soc. Amer. Abs. with Programs, v. 9, p. 1175-1176.

Silver, E. A., 1977, Are the San Gregorio and Hosgri faultzones a single faul't system'P (Abstract): Geol. Soc.Amer. Abs. with programs, v. 9, p. 500.

Silver,-E. A., 1978, Geophysical studies and tectonic develop-ment of the continental margin off the western UnitedStates, 34'o 48 N: in Geol. Soc. America Memoir,Smith, R. B. and Eaton, G. P., eds., (in press).

Silver, E. A. and Moore, J. C., 1978, The Molucca Seacollision zone, Indonesia: Jour. Geophys. Res., v. 83.

Blake, M. C., Campbell, R. H., Dibblee, T. H., Howell, D. G.,Nilsen, T. H., Normark, N. R., Vedder, J. G., andSilver, E. A., 1978, Neogene basin formation and hydro-carbon accumulation in relation to the plate tectonicevolution of the San Andreas fault system, California-Amer. Assoc. Petroleum Geol. Bull., March 1978.

Silver, E. A., 1978, The San Gregorio-Hosgri fault zone:An overview: Calif. Div. Mines and Geol. SpecialPub. 137.

Silver, E. A., McCulloch, D. S., and Curray, J. R., 1978,Marine geology and tectonic history of the centralCalifornia continental margin: Submitted to AAPG.Bull.

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ATTACHMENT C

BZOGRAPBY

CLARENCE A. EKL JR.

Social Security Number:

569-34-9229

Address: 2427 S. Armacost Avenue 820Los Angeles, CaZi foznia 90025

Home 2'elephone:

(223) 473-3061

Bvainess 2'e Zephone:

(223) 825-2020

Date of Birth:

Born:

, xi~Le:Eaum~tz m:

January 5, 1930 - Citizen of the United StatesLos AngeZes, CaHforniaProp essoz'f Geologp

B. S., Stanford University, 2952lA S., Sta. ford University, 2953Pn.D., S~„-"ord University, 2956

Pa"t ciployment:Romd Valley Pmgsten Nine, Bishop, CaHfornia, Geologist, 2952U.S. C~ological Suey (Or gon), Geologist, 1953Unive sity of Oregon, 1'nstrv tor in Geology, 2954-55Z~Ze Oil ~n Refining Ccnvany, Geologist, 2955Stanford University, lnst~mtor in GeoZogp, 2956Suv..er ~.,pKoyment, V.S. Geological Survey, Geologist, 2972-78Vniversi='w of California, Los Angeles, Assistant Pz'ofessoz to

Professor, 2966 to Present; Chairman, Depa~~.ent of Geology,9-2-74 to 22-31-76, Acting Chairman, Department of Geophysicsand Space Physics 8-2-76 to 12-31-76, Chairman, Depaztmentof Eazth and Space Sciences 1-2-77 to 8-32-78

Scholarly Societies:ZeZZ~ GeologicaZ Society of AmericaPaleontological Society of America —Editor Journal of

PaZeontology, 1971-72NalacoZogicaZ Society of CaZi foznia

Zonors and Awards:

Zulbright Research Scholaz; 2taly, 2963-64 and 2970-72invited Lectvwer, PoHsh Academy of Science, 2964

C. A. Halls ~ ~

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6.

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1958

1958

1959

- 1959

1959

1959

1960

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Geology and paleontology of the Pleasanton area,Alameda and contra Costa Counties, Calif.: Univ.Calif. Pub- Geol. Sci., v. Q4, no. 1, p. 1-90, pls.l-l2, 2. figs; 5 maps.

Gastropod Genus Ceratostoma Geol. Soc. Asser .Bull.,69, . 12, I . RR~. S 7. (ABII'IIICI'I

The Gast opod, Genus 'Ceratostoma: Jour. Paleontolo~,v. 33, no. 3, p. 428-430, 3 pls. 1959.

Pigeon point Formation of Late Cretaceous age, San ElateoCo. Caliz.: Amer. Assoc. Patrol. Geologists Bull.,v. 5, no. 12, p. 2855-2859, 1959.

E

Displaced IO.ocene VG3.luscan Provinces along the'anAndreas ault. Pacific Petroleum Geologist Newsletter,Amer. Assoc. Petro3.. Geol., v. 13, no.- 3, p. 4. (ABSTRACT)

Displaced 1 iocene Molluscan Provinces along the SanAndreas F"ult, Calif., Geological Society of America

r-- s +(+. s r t n sgt, s s s s.> n s ss ss sym.x., v. jO, no. 12, pt., p.

Displaceh '.!iocene Molluscan Provinces Alongthe San 9 d eas Fault,, Calif.: Univ. Cali . Pub.Geol. Soc.~ v. 3LI, no; 6, p.- 281-308.

Ceratos i G .a Herrmannsen, 1%6 (Class Gastropoda);propose"'dition to the Official list of GenericHam s. A. Fi. (S) 1088: Bull,. Zoo3.. Homencl., v. 18,pt. 5, p. 336, 1961.

Geolog c Yap of California, San Francisco Sheet,Calif. Div. of I4ines, 1961 (Contributor).

3.0. 1962

12. 1962

1964

11. 1962

Displaced Miocene Yiolluscan Provinces along the SanAndreas Fault in Guidebook, Geology of'arrizo plainsand San Andreas Fault, 1962: pac. Sec. Amer. Assoc.Petro3.. Geol., p. 20, 1962.-

'I

Displaced Viocene molluscan provinces along the SanAndreas Fault, Calif'.: Amer. Assoc. Petro3.. Geol.,v. 06, no. 10, p. 1952-3.960, 1962.

Evolution of the echinoid genus Astrodapsis: Univ.Calif. Pub. Geol. Sci., v. 40, no. 2, p. $7-180, 1962.

Area Arc" lepton;ramnica, a new lateTertiary'e

ecypo Erom .ze San Luis Obi"po Pegion, Calif'.:Jour. paleo., v. 3U, no. 3., p. 87-88, 3.96>i.

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27- 1970

28.. 1973

29. 1973

3O- 1973-

~ ~~ e 1 ~

The Obis~ Formation and as ociat~volcanic rock in.the Gentle. California Coast Range~- K-Ar'ages andbiochronologic signif'icance. Geol. Soc. Americaab'stracts with programs, Cordilleran Section, 66thAnnual meeting, v- 2, no. 2, (srith D. L. Turner and, R.C. Surdam).

Geology of the Arroyo Grande quadrangle, San LuisObispo Co., Californ a: C"lif- Div. of Nines and .

Geology Nap Sheet 24. ~ ~

Geologic map of the Morro Bay South and port San Luisquadrangles, San Luis Obispo Co., California. U. S.

'eological.Survey 1G'11 Map Series.P

Oligocene and Miocene Felsic Volcanism, Nest Centra3.California Coast Ranges, Amer,. Geophys. Union Iieeting,Fall, 1973 (abstract} (~rith 8. G. Ernst).

197'974

1970

32.

33 197<

3)+.

35-'975

Shell gro;i-~h in Tivela stultorum (Mawr, 1823) andca11me chione TL'nnaeue, 1(55 Iaiva1via): Annua1perxoc'city, latitudinal differences and diminution

~with age, (rrith >T. A. Dollase and C. E. Corbato).'Palaeo~eography, Palaeoclimatalogy.. Paleoecology.v 3.5> p. 33»61.

G ology and Petrology of he Cambria Felsite a Hetr03.i=ocen Formation 'tTest Central Calif. Coast Ranges.Geol. Soc. Amer. Bu13 , v. U5> p 523 532 'Nith7T. G. Ernst).Geo" og' I:ao of the Cambria Region, .San Lu- s OD ispoCounty, California. U. S .,Geological Survey,

Miscellaneous F'eld Studies Map 599 in 1974.\

Lati ud, nal variation in shell grosrth patterns ofbivalve'mo3~uscs: implications and problems: He@castle .

Symposium, Vol.; 1974.

Latitudinal variation in shell growth patterns ofbivalve moI3.uses: implications and problems. p. 163-173In Growth Rhythms and the history of the Earth'rotation, G. D. Rosenberg and. S. K. Runcorn eds.John 3/iley and Sons.

36. 1975 Feldspathic Geodes Hear Black Mountain, Western SanLuis Obispo County, California, Geol. Soc. Amer.,abstracts ~"ith programs, Cordilleran Section, 73.stAnnual I,"ecting, March, 1975. (With lT. G. Ernst)(ABS RACTe)

~ 37- 1975 Geologic map of the Cayucos-San Lui" Obispo repion.U. S- Geol. Surv. Misc. Field Studies Map, M; 686

C-4

~ ~

i 38. 1975

39. 1975

40. 1975

41. 1976

42. 1976

IN PRESS

IN PRE-PARATION

Fe I dsp hi c geodes near B lack Mo&ta i n, wes ternLuis Obispo County, California: Amer. Min., V. 60,'. 1105-1112. (with M. G. Ernst)

San Simeon-Hosgri fault system, coastal Cali fornia:economi c and, env i ronmenta I imp I i cat i ons . U.S.Geological Survey Open Fi le Rept., 75-533, 12manuscript pages.

San Simeon-Hosgri fault system,'oastal Cali fornia:economi c and env i ronmenta I imp I i cat i ons . Sci ence,v. 190, 'p. 1291-1293.

Geologic Map of the San Simeon-Piedras BlancasRegion, San Luis Obispo County, Cali fornia: U.S.Geo log i ca I Survey Mi sc. Fi e I d Studi es Map, MF 784,scale of I:24,000.

Origin and development of the Lompoc-Santa Hariapull-apart Basin and its relation to the San Simeon-Hosgri Fault, Cali fornia: Geological Society ofAmer i ca (ABSTRACT)

Geologic Map of the Santa Haria Val ley Region, Santa"Barbara County, Cali fornia: U.S. Geological Survey.Misc. Field Studies Map, scale of I:24,000.

Cerozoi c bas'ins, Centra I Ca I i forni a, (Probably'aliforniaDivision of Hines wi I I, publish GSA

Sy-posium papers (see abstract 4'42 for generaldi'scuss ion) .

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ATTACHMENT D

Stephan Alan Graham2136 Greenwood Dr.San Carlos, CA 94070

GeneralBorn 4/25/50, Evansville, Indianahhrried 5/27/72, wife-Pmela, 1 childU.S. citizen, military status-lH, foreign language-German

EducationA.B. Indiana University . 1972M.S. Stanford University 1974Eh.D. Stanford Unive sity 1976

Geology, with HonorsGeology I

Geology

Specialization: Sedimentary geology, in particular sedimentary tectonics

Thesis: addle Tertiary paleogeography and structural development of theSalinian block, California; Eh.D. committee: W. R. Dickinson(advisor), J. C. Ingle, Jr., B. M. Page

5 1973:

7. 1976:

Professional Ecperiencel. 1968, 1970: Subsurface mapping, Fritz Operating Co., Ft. Branch, Ind.,(summers )

2. 1970: X-ray diffractometer technician, Indiana Univ., Bloomington,Ind., (part-time)

3. 1971-1972: Consulting geologist for Peninsula Exploration Co., CorpusChristi, Texas, (part-time )

4. 1972: Associate Instructor, Indiana University Geologic FieldStation, Cardwell, hantana, (summer )Research assistant, Stanford University, Stanford, Ca.,(summer'

6. 1973: Instructor, Stanf'ord Geological Survey, Bridgeport, Ca.,(summer )Research Geologist, Exxon Production Research Co.,Houston, Texas

8. 1,976- Exploration Geologist, Chevron USA Inc., San Francisco, CA

Awards,1.2 ~

3 ~

5 ~

6.7 ~

8.

Assistantships, and FellowshipsEarth Sciences Freshman Scholarship, Indiana University, 1968Arthur R. hertz Distinguished Scholarship, Indiana University, 1968-1972Indiana University Geologic Field Station tuition award, 1969Standard Oil of'exas undergraduate geology award, 1969, 1970Best student paper, Rocky Mtn. Section, Geol. Soc. America, 1971Senior faculty scholarship award, 3adiana University, 1972%hi Beta Kappa, 1972National Science Foundation Graduate Fellowship, 1972-1975

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Professional SocietiesGeologica1 Society of AmericaSigma XiSociety o Zconomic Paleontologists and Mineralogists

PublicationsGraham, S.A., 1971, Occurrence of middle Cambrian islands in southwest

&ntana: Geol. Soc, America Abs. with Programs, Rocky Mtn. Section,383-384.

Graham, S.A., and Suttner, L.J., 1974, Occurrence of middle Cambrianislands in southwest leant ~a: %he bhuntain Geologist, v. 11, 71-84.

Graham, S.A., 1974, Remanant magnetization of modern tidal flat sedimentsfrom San Francisco Bay, California: Geology, v. 2, 223-226.

Graham, S.A., Dickinson, W.R., and Ingersoll, R.V.> 1975, Himalayan-Bengalmodel for flysch dispersal in the Appalachian-Ouachita system:Geol. Soc. America Bu11., v. 86, 4 3, 273-286.

Dickinson, W.R., and Graham, S.A., 1975, Sedimentary environments, depositionalsystems and stratigraphic cycles in current concepts of depositicnal systemswith applications for petroleum geology; W.R. Dickinson, editor:San Jo~uin Geological Society Short Course, Bakersfield, 1-10.

Graham, S.A., 1975, Tertiary sedimentary tectonics of the centralSa1inian block of California: Geol. Soc. America Abstracts with programs>v. 7, no. 7, 1089.

Graham, S.A., 1976, Tertiary sedimentary tectonics of the central Salinianblock of California: Eh.D. Dissertation, Stanford University, Stanford,California, 510 p.

Graham, S.A., 1976, Tertiary stratigraphy and depositional environments nearIndians Ranch, 1hnterey County, California: The Neogene Symposium,Pac. Sect., Soc, Econ. P01eontologists and 5!ineralogists, 125-136.

Grahmn, S.A., 1976, Tertiary stratigraphy and depositional environments nearIndians Ranch, bbnterey County, Ca1ifornia: Amer. Assoc. of MtroleumGeologists Bull. (abs. ), 2181-2182.

Graham, S.A., 1976, San Gregorio Fault as a major right-slip fault of theSan Andreas Fault system: Geol. Soc. America Abstracts with Programs,v. 8, no. 6, 890.

Graham, S.A., Ingersoll, R. V., and Dickinson, W.R., 1976, Common provenancefor lithic grains in Carbon'erous from Ouachita t~ountains and BlackWarrior Basin: Journal of Sedimentary Petrology, v. 46, 620-632

Dickinson, W.R., Graham, S.A., and Ingersoll, R.V., and Jordan T.Z., 1976pApplication of plate tectonics to petroleum geology along the Pacificmargin of North America: Aner. Assoc. Petroleum Geologists Bull.(abs), 2179.

Graham, S.A., and. Dickinson, W.R., 1977, Apparent offsets of onl'and geologicfeatures across the San Gregorio-Hosgri fault trend: Geol. Soc. AmericaAbstracts with Programs, v. 9, no. 4, 424.

Graham, S.A., and Dickinson, W.R., 1978, Apparent offsets of on1and geologicfeatures across the San Gregorio-Hosgri fault trend: Science, v. 199,179-181. =

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Graham, S.A., and Dickinson, V.R., 1978, Apparent offsets of onland geologicfeatures across the San Gregorio-Hosgri fault trend: Calif. Div. Yiinesand Geology Special Report (in press).

Graham, S.A., 1978, Role of the Salinian block in the evolution of theSan Andreas fault system: Amer. Assoc. Petroleum Geologists Bull.,v. 62, g ll (in press).

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Telephone(415) 894-0308 (office 8:00 AM - 4:00 PM.)(415) 595-2036 (home )

Curriculum Vitae - Wm. R. Dickinson

Born: Nashville, Tennessee, Oct. 26, l931

Degrees (all Stanford University):

B.S., Pet. Engr. 1952M.S., Geology 1956Ph.D., Geology 1958

USAF, 1952-1954

Faculty Positions (all Stanford Univ.):

Acting Assistant ProfessorAssistant ProfessorAssociate ProfessorProfessor

1958-601960-631963-681968-Present

Guggenheim Fellow 1965

Articles in Science, Nature,'eol. Soc. America Bull., Jour. Geophys.Research, Am. Jour Sci., Am. Assoc. Petroleum Geologists Bull., Jour.Sediment. Petrology, Sediment. Geology, Tectonophysics, Earth andPlanetary Sci. Lettrs., Rev. Geophysics and Space Physics, Can. Jour.Earth Sci.

Member of Geol. Soc. America (Fellow), Am. Assoc. Petroleum Geologists,Am. Geophys. Union, Soc. Econ. Paleontologists and Hineralogists,Nat. Assoc. Geology Teachers, Am. Assoc. Adv. Sci.

Chairman, Cordilleran Sec., Geol. Soc. America (1974-1975);President, Peninsula Geol. Soc. (1977-1978);Councillor, Geol. Soc. America (1977-1980).

A. I. Levorsen Memorial Award, Pac. Sec., Am. Assoc. Petroleum Geologists(1978-1979) .

Ma or Conference Partici ation

1966 — speaker, Symposium on Circum-Pacific Orogenesis, Pacific ScienceCongress, Tokyo, Japan.

1967 — co-convener, Joint USGS-Stanford'Conference on Geologic Problems ofSan Andreas Fault System, Stanford University.

1967 - speaker, IUGG-IAV Conference on Andesites, Oregon Institute forVolcanology.

1969 — speaker, Andesite Symposium, Volcanic Studies Group, GeologicalSociety of London.

1969 - convener, GSA Penrose Conference on Plate Tectonics and OrogenicBelts, Asilomar, California.

1970 — co-organizer, Symposium on Cretaceous Geology of Central California,GSA Cordilleran Section Meeting, Hayward, California,.

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1971 — co-organizer and speaker, NAS Symposium on Plate Tectonics,Washington, D.C.

1971 — keynote speaker, Symposium on Petrology and Geochemistry of IslandArcs in Relation to Tectonic Environment, Pacific Science Congress,Canberra, Australia.

1971 — organizer and keynote speaker, Symposium on Plate Tectonics inGeologic History, National GSA meeting, Washington, D.C.

1972 — speaker, Carnegie Institute Conference on Plate Tectonics andthe'volutionof Continents, Airlie, Virginia.

1972 — speaker, Joint NSP-Wisconsin Conference on Ancient and ModernGeosynclinal Sedimentation, Madison, Wisconsin.

1973 — convener, SEPM Research Symposium on Tectonics and Sedimentation,AAPG-SEPM Nat. Mtg,, Anaheim, California.

1974 — speaker, GAC Symposium on Volcanic Geology and Mineralization inthe Canadian Cordillera, Vancouver, Canada.

1974 — convenor and speaker, San Joaquin Geological Society Short Courseon Plate Tectonics and Petroleum Geology, Bakersfield, California.

1975 — convenor and speaker, San Joaquin Geological Society Short Course o'Depositional Systems and Petroleum Geology, Bakersfield, California.

1975 — Speaker, Symposium on Circum-Pacific Magmatism, Metamorphism, andSedimentation, Pacific Science Congress, Vancouver, Canada.

1976 — invited speaker, Ewing Symposium of Lamont-Doherty GeologicalObservatory, Harriman, New York.

1976 — convenor and speaker, Symposium on Pre-Tertiary of Blue MountainsProvince, GSA Cordilleran Section Meeting, Pullman, Washington.

1976 — instructor, AAPG Short Course on Plate Tectonics and HydrocarbonAccumulation, AAPG National Meeting, New Orleans, Louisiana.

1976 — speaker, SEG Short Course on Plate Tectonics and Sedimentary Basins,SEG National Meeting, Houston, Texas.

1977 — speaker, Symposium on Paleozoic Paleogeography of the Pacific Coast,Pacific Section SEPM Meeting, Bakersfield, California

1977 — speaker, AAPG Short Course on Continental Margins, AAPG NationalMeeting, Washington, D.C.

1978 — keynote speaker, International Geodynamics Conference on the WesternPacific, Tokyo, Japan.

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1978 — speaker, Symposium on Mesozoic Paleogeography of the Pacific Coast,Pacific Section AAPG Meeting, Sacramento, California.

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List of Publications in Geolo ical Science b William R. Dickinson

WRD,

WRD,

1958, Mesozoic marine clastic rocks of volcanic derivation in southwesternGrant County, Oregon (abs}: Geol. Soc. America Bull., v. 69, p. 1554.

1959, Structural relationships of Church Creek and Willow Creek Faults,Santa Lucia Range, California (abs.): Geol. Soc. America Bull., v. 70,p. 1715.

1960, Geology of the Izee area, Grant County, Oregon (abs): Dissert. Abs.,v. 20, no. 11 (1958 Ph.D).

1960, Petrology of Jurassic marine tuffs, central Oregon (abs)': Geol. Soc.America Bull., v. 71, p. 2056.

1961, Jurassic andesitic province along the Pacific margin of North America(abs): Geol. Soc. America Abs. for 1961, p. 19.

1962, Brecciated serpentine extrusion on Table Mountain in central CaliforniaCoast Ranges (abs).: Geol. Soc. America Abs. for 1962, p. 34.

1962, Marine sedimentation of clastic volcanic strata (abs): AmericanAssoc. Petroleum Geologists Bull., v. 46, p. 263.

1962, Hetasomatic quartz keratophyre in central Oregon: Am. Jour. Sci.,v. 260, p. 249-266.

1962, Petrology and diagenesis of Jurassic andesitic strata in centralOregon: Am. Jour. Sci., v. 260, p. 481-500.

1962, Petrogenetic significance of geosynclinal andesitic volcanism alongthe Pacific margin of North America: Geol. Soc. America Bull., v. 73,p. 1241-1256.

1963, Tertiary stratigraphic sequence of the Hancock Ranch area, Montereyand Kings Counties, California: Pac. Sec. Am. Assoc. Petroleum Geologists-Soc. Econ. Paleontologists and Hineralogists Ann.Field Trip Guidebook toGeology of Salinas Valley and San Andreas Fault, p. 47-53.

WRD and L. W. Vigrass, 1964, Pre-Cenozoic history of Suplee-Izee district,Oregon: . implications for geosynclinal theory: Geol. Soc. America Bull.v. 75, p. 1037-1044.

WRD, 1965, Folded thrust contact between Franciscan rocks and Panache Group inthe Diablo Range of central California (abs): Geol. Soc. AmericaSpecial Paper 82, p. 248-249.

WRD and L. W. Vigrass, 1965, Mesozoic history of Suplee-Izee district, centralOregon (abs): Geol. Soc. America Special Paper 82, p. 325.

WRD and J. G. Smith, 1965, Geological relations of the Koroimavua Group innorthwest Viti Levu: Fiji Geol.. Survey Dept. Note 121, 4 p.

WRD and J. G. Smith, 1964, Geological road log from Nandi International Airportto the Nausori Highlands: Fiji Geol. Survey Dept. Note 122, 6 p.

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~ ~ ~Publications, William R. Dickinson

Page two

Smith, J.G. and WRD, 1965, A geological reconnaissance of the southern Ya'sawaIslands: Fiji Geol. Survey Dept. Note 125, 6 p.

WRD and L.W. Vigrass, 1965, Geology of the Suplee-Xzee area, Crook, Grant, andHarney Counties, Oregon: Ore. Dept. Geology and Mineral Industries Bull.No. 58, 109 p.

WRD, 1965, Tertiary stratigraphy of the Church Creek area,'onterey County,California: Calif. Div. Mines and Geology Special Rpt. 86, p. 25-44.

WRD, 1966, Problems of stratigraphic nomenclature in Fiji (South-West PacificGeological Survey Conference Paper): Fiji Geol. Survey 'G. S. Note 9/66,10 p.

WRD, 1966, Table Mountain serpentinite extrusion in California Coast Ranges:Geol. Soc. America Bull., v. 77, p. 451-472.

WRD, 1966, Structural relationships of San Andreas fault system, Cholame Valleyand Castle Mountain Range, California: Geol. Soc. America Bull., v. 77,p. 707-726.

WRD, 1966, Petrography of specimens from the Mamanutha Group: Fiji Geol. SurveyDept. G. S. Note 20/66, 5 p.

WRD and D.R. Lowe, 1966, Stratigraphic relations of phosphate- and gypsum-bearing upper Miocene strata, upper Sespe Creek, Ventura County, California:Am. Assoc. Petroleum Geologists Bull., v. 50, p. 2464-2470.

WRD, 1967, Circum-Pacific andesite types (abs): Am. Geophys. Un. Trans., v. 48,p. 253.

WRD and Trevor Hatherton, 1967, Andesitic volcanism and seismicity around thePacific: Science, v. 157, p. 801-803.

WRD, 1967, Tectonic development of Fiji: Tectonophysics, v. 4, p. 543-553.

WRD, 1967, Problems M stratigraphic nomenclature in Fiji (abs): N.Z. Jour.Geology and Geophysics, v. 10, p. 1181-1182.

WRD, 1968, Circum-Pacific andesite types: Jour. Geophys. Res., v. 73,p. 2261-2270.

WRD and Arthur Grantz (eds), 1968, Proceedings of conference on geologic problemsof San Andreas fault system: Stanford Univ. Pub. Geol. Sci., v. 11, 375 p.

WRD, 1968, Sedimentation of volcaniclastic strata of the Pliocene KoroimavuaGroup in northwest Viti Levu, Fiji: Am. Jour. Sci. v. 266, p. 440-453.

I

Hatherton, Trevor and WRD, 1968, Andesitic volcanism and seismicity in NewZealand: Jour. Geophys. Res., v. ?3, p. 4615-4619.

WRD, M.J. Rickard, F. X. Coulson, J. G. Smith, and R.L. Lawrence, 1968, LateCaenozoic shoshonitic lavas in northwestern Viti Levu, Fiji: Nature,v. 219, p. 148.

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Public ons, William R. Dicki~»;onPage t)tree

WRD, 1968, Comparison of California's Franciscan assemblage and Great Valleysequence to New Zealand's axial and marginal facies (abs): Geol. Soc.America Special Paper 115, p. 322.

WRD, 1968, Singatoka dune sands, Viti Levu, Fiji: Sed. Geology, v. 2,p. 115-124.

WRD, 1968, Blend of teaching and research (letter): Science, v. 162, p. 1221.

Noble, D.C., WRD, and Clark, M.M., 1969, Collapse caldera in the Little Walkerarea, Mono County, California (abs): Geol. Soc. America Special Paper121, p. 536-537.

Rich, E.I., R.W. Ojakangas, WRD, and Win Swe, 1969, Sandstone petrology ofGreat Valley sequence, Sacramento Valley, California (abs): Geol. Soc.America Special Paper 121, p. 550.

WRD, R.W. Ojakangas, and R.J. Stewart, 1969, Burial metamorphism of the lateMesozoic'reat Valley sequence, Cache Creek, California: Geol. Soc.America Bull., v. 80, p. 519-525.

WRD, 1969, Evolution of calc-alkaline rocks in the geosynclinal system of .

California and Oregon, p. 151-156 in McBirney, A.R. (ed), Proceedingsof andesit'e conference: Ore. Dept. Geology and Mineral Industries Bull.65, 193 p.

In Pac. Sec. Soc. Econ. Paleontologists and Mineralogists, 1969, Field TripGuidebook (WRD, ed): Geologic setting of upper Miocene gypsum andphosphorite deposits, upper Sespe Creek and Pine Mountain, Ventura

'ounty,California, 91 p.:

(a)

(b)

(c)

(d)

WRD (p. 1-24), Geologic problems in the mountains betweenVentura and Cuyama.

WRD (p. 49-55), Miocene stratigraphic sequence on upperSespe Creek and Pine Mountain.

WRD (p. 63), quaternary terrace gravels and colluvium onsouth side of Pine Mountain.

WRD (p. 68-77), Road log, Ojai. to Ozena.

Hatherton, Trevor and WRD, 1969, The relationship between andesitic volcanismand seismicity in Indonesia, the Lesser Antilles, and other,i.sland arcs:Jour. Geophys. Res., v. 74, p. 5301-5310.

Swe, Win and WRD, 1970, Sedimentation and thrusting of late Mesozoic rocks inthe Coast Ranges near Clear Lake, California: Geol.'oc. America Bull.,v. 81, p. 165-188.

WRD, 1970, Tectonic setting and sedimentary petrology of the Great ValleySequence (abs): Geol. Soc. America Abs. with Progs.; v. 2, p. 86-87.

Gilbert, W.G. and WRD, 1970, Stratigraphic variations in sandstone petrology,Great Valley Sequence, central California coast: Geol. Soc. AmericaBull., v. 81, p. 949-954.

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Publi .ons, Wflliam k. DickinsonPage four

lWRD and Page, B.M., 1970, Central California Coast Ranges: Guide to Field Trip

No. 1, Cordilleran Sec., Geol. Soc. America Ann. Mtg. 1970, 25 p.

WRD, 1970, The new global tectonics (report: 2nd Penrose Conference): Geotimes,v. 15, no. 4, p. 18-22.

WRD l1970, Global tectonics (report: 2nd Penrose Conference): Science, v. 168,p. 1250-1259.

WRD, 1970, Interpreting detrital modes of graywacke and arkose: Jour. Sed.Petrology, v. 40, p. 695-707.

1970, Relations of andesitic volcanic chains and granitic batholith beltsto the deep structures of orogenic arcs: Geol. Soc. London Proc.,no. 1662, p. 27-30.

1970, Geology and geologists in regional planning (abs): Geol. Soc.America Abs. with Progs., v. 2, p. 738-739.

WRD, 1970, Geology for the Masses: Jour. Geol. Education, v. 18, p. 194-197.

1970970, Relations of andesxtes, granites, and derivative sandstones toarc-trench tectonics: Rev. Geophys. and Space Phys., v. 8, p. 813-862;

WRD, 1971, Detrital modes of New Zealand" graywackes: Sed. Geology, v. 5,p. 37-56.

1971, Plate tectonics (developments during 1970): Geotimes, v. 16, p. 21.

1971, Plate tectonic models of geosynclines: Earth and Planet. Sci.Lettrs., v. 10, p.,165-1?4.

1971, Clastic sedimentary sequences deposited in shelf, slope, and troughsettings between magmatic arcs and associated trenches: Pac. Geology,v. 3, p. 15-30.

WRD 19?9?1, Plate tectonic models for orogeny at continental margins: Nature,v. 232, p. 41-42.

WRD, 1971, Complementarity (letter): Science, v. 173, p. 1191-1192.

WRD, 1971, Ecological questionnaire (letter): Natural History, v. 80, no. 2,p. 101.

WRD 19 71 R971, Reconstruct@on of past arc-trench systems from petrotectonicassemblages in island arcs (abs): 12th Pac. Sci. Congr. Proc., v. 1,p. 445.

WRD, 1971, Plate tectonics in geologic history: Science, v. 174, p. 107-113.

WRD, 1971, Evidence for plate tectonic regimes in the past: Geol. Soc.America Abs. with Prog., v. 3, p. 544.

WRD and W.C. Luth, 1971, A model for plate tectonic evolution of mantle layers:Science, v. 174, p. 400-404.

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Publicana, William R. Dickinr~nnPage five

WRD, D.S. Cowan and R.A. Schweickert, 1972, Test of new global tectonics(discussion):- Am. Assoc. Petroleum Geologists Bull., v. 56, p. 375-384.

WRD, 1972, The Earth Sciences (second edition), A.N. Strahler (review): Am.Geophys. Un. Trans. (EOS), v. 53, p. 258-260.

Wright, R.M. and WRD, 1972, Provenance of Eocene volcanic sandstones in easternJamaica; a preliminary note: Carib. Jour. Sci., v. 12, p. 107-113.

WRD, 1972, Plate tectonics symposium (preface): Am. Jour. Sci., v. 272,p. 549-550.

WRD, 1972, Evidence for plate-tectonic regimes in the rock record: Am. Jour.Sci., v. 272, p. 551-576.

WRD, 1972, Dissected erosion surfaces in northwest Viti Levu, Fiji: Zeitschr.f. Geomorph. N.F., v; 16, p. 252-267.

Hedge, C.E.,Samoa:

WRD and E.I.Valleyv. 83,

Z.E. Peterman, and WRD, 1972, Petrogenesis of lavas from WesternGeol. Soc. America Bull., v. 83, p. 2709-2714.

Rich, 1972, Petrologic intervals and petrofacies in the Greatsequence, Sacramento Valley, California: Geol. Soc. America Bull.,p. 3007-3024.

Mader, G.G., E.A. Danehy, J.C. Cummings, and WRD, 1972, Land use restrictionsalong the San Andreas fault in Portola Valley, California, p. 845-858 inSherif, M.A. and R.C. Bostrom (eds), Proceedings of the InternationalConference on Microzonation fox Safer Construction, Seattle, Wash., 987 p.

WRD, 1973, Tettonica a zolle e catene montuose, art. 10, p. 190-'200 inEnciclopedia della scienza e della tecnica 73: Edizioni scientifichee techniche, Mondadori, Milano, Italy.

WRD, 1973, Widths of modern arc-trench gaps proportional to past duration ofigneous activity in associated magmatic arcs: Jour. Geophys. Res., v. 78,p. 3376-3389.

WRD, 1973, Reconstruction of past arc-trench systems from petrotectonicassemblages in the island arcs of the western Pacific, p. 569-601 inColeman, P.J.'ed), The western Pacific; island arcs, marginal seas,geochemistry: Univ. Western Australia Pxess, Perth, 601 p.

WRD, 1974, Review of arc volcanism (abs): Geol. Assoc. Canada Cordilleran Sec.Programme and Abstracts, p. 9-10.

In WRD (ed), 1974, Geologic interpretations from global tectonics with applica-tions for California geology and petroleum exploration: San JoaquinGeological Society Short Course, Bakersfield, 75 p.

(a) WRD (p. 2-1 to 2-5), Geologic implications of plate tectonics.(b) WRD (p. 9-1 to 9-6), Plate tectonics and sedimentary basins.(c) WRD (p. 15-1 to 15-4), Plate tectonics andmigration of petroleum.

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Publica s, William R. DickinsonPage six

Noble, D.C., D.B. Slemmons, M.K. Korringa, WRD, Yehya Al-Rawi, and E.H. McKee,1974, Eureka Valley Tuff, east-central California and adjacent Nevada:Geology, v. 2, p. 139-142.

WRD, 1974, Sedimentation within and beside ancient and modern magmatic arcs,p. 230-239 in Dott, R.H., Jr., and R.H. Shaver (eds), Modern and ancientgeosynclinal sedimentation: Soc. Econ. Paleontologists and MineralogistsSpecial Pub. No. 19, 380 p.

Baldwin,. Brewster, P.C. Coney, "and WRD, 1974, Dilemma of a Cretaceous time scaleand rates of sea-floor spreading: Geology, v. 2, p. 267-270.

WRD, 1974, Subduction and oil migration: Geology, v. 2, p. 421-424.

WRD, 1974, Plate tectonics and sedimentation, in Dickinson, W.R. (ed), Tectonicsand sedimentation: Soc. Econ. Paleontologists and Mineralogists SpecialPub. No. 22, p. 1-27.

WRD, 1974, Island arcs; Japan and its environs (review): Jour. Geology v. 82,p. 529.

WRD, 1975, Potash-depth (K-h) relations in continental margin and intraoceanicmagmatic arcs: Geology, v. 3, p. 53-56.

In WRD (ed), 1975, Current concepts of depositional systems with applicationsfor petroleum geology: San Joaquin Geological Society Short Course,Bakersfield, 105 p.

(a)

(b)

(c)(d)

WRD and S.A. Graham (p. O-l to 0-10), Sedimentary environments,depositional systems, and stratigraphic cycles.WRD (p. 1-1, to 1-16), Fluvial sediments of stream valleys andalluvial fans.WRD (p. 5-1 to 5-8), Deltaic deposits and cyclothems.WRD (p. 12-1 to 12-4), Hydrocarbon occurrences in relation todepositional systems.

Graham, S.A., WRD, and Ingersoll, R.V., 1975, Himalayan-Bengal model for flyschdispersal in Appalachian-Ouachita system: Geol. Soc. America Bull.,v. 86, p. 273-286.

WRD, 1975, Problems of pre-Tertiary tectonic correlations across the PacificNorthwest (abs): Geol. Soc. America Abs. with Progs., v. 7, p. 604.

WRD, 1975, Geology and oil (review): Science, v. 189, p. 133-134.

WRD, 1975, Time-transgressive tectonic contacts bordering subduction complexes(abs): Geol. Soc. America Abs. with Progs., v. 7, p. 1052.

Snyder, W.S., WRD, and M.L. Silberman, 1975, Tectonic implications of space-time patterns of Cenozoic magmatism in the western United States (abs):Geol. Soc. America Abs. with Progs., v. 7, p. 1279.

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Public ns, William R. DickinsonPage seven

WRD, 1975, Sedimentary basins developed during evolution of Mesozoic-Cenozoicarc-trench system in western North America (abs): - 13th Pacific Sci.Congr. Abs., p. 397-398.

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WRD and W.S. Snyder, 1975, Geometry of triple junctions and subducted litho-sphere related to San Andreas transform activity (abs): Am. Geophys.Un. Trans. (EOS), v. 56, p. 1066.

WRD, K.P. Helmold, and J.A. Stein, 1976, Paleocurrent trends and petrologicvariations in Mesozoic strata near South Fork of John Day River, centralOregon (abs): Geol. Soc. America Abs. with Progs., v. 8, p. 368-369.

WRD, 1976, Sedimentary basins developed during evolution of Mesozoic-Cenozoicarc-trench system in western North America: Can. Jour. Earth Sci., v. 13,p. 1268-1287.

Snyder,,W.S., WRD, and Silberman, M.L., 1976, Tectonic implications of space-time patterns .of Cenozoic magmatism in the western United States: EarthPlanet. Sci. Lettrs., v. 32, p. 91-106.

Graham, S.A., R.V. Ingersoll, and WRD, 1976, Common provenance for lithicgrains in Carboniferous sandstones from Ouachita -Mountains and BlackWarrior Basin: Jour. Sed. Petrology, v. 46, p. 620-632.

WRD, 1976, Plate tectonics and hydrocarbon accumulation: Am. Assoc. PetroleumGeologists Continuing Education Course Note Ser. No. 1, 61 p.

Graham, S.A. and WRD, 1976, San Gregorio fault as a major right-slip fault ofthe San Andreas fault system (abs): Geol. Soc. America Abs. with Progs.,v. 8, p. 890.

Ingle, J.C., Jr., S.A. Graham,, and WRD, 1976, Evidence and implications ofworld-wide late Paleogene climatic and eustatic events (abs): Geol. Soc.America Abs. with Progs., v. 8, p. 934-935.

WRD, 1976, The way the earth works; an introduction to the new global geologyand its revolutionary development (review): Jour. Geology, v. 84, p. 502.

Casey, T.A.L. and WRD, 1976, Sedimentary serpentinite of the Miocene Big Blue. Formation near, Cantua Creek, California (abs): Am. Assoc. Petroleum

Geologists Bull., v. 60, p. 2177.

WRD, S.A. Graham, R.V. Ingersoll, and T.E. Jordan, 1976, Applications of platetectonics to petroleum geology along the Pacific margin of North America(abs): Am. Assoc. Petroleum Geologists Bull., v. 60, p. 2179.

Casey, T.A.L. and WRD, 1976, Sedimentary serpentinite of the Miocene Big BlueFormation near Cantua Creek, California, in Fritsche, A.E. H. Ter Best, Jr.,and W.W. Wornardt (eds),. The Neogene Symposium: Pac. Sec. Soc. Econ.Paleontologists and Mineralogists Ann. Mtg., p. 65-74.

WRD, 1977, Fossil fuels and continental drift: Basterfield Lec. Ser. No. 19,Univ. Regina, Saskatchewan, 16 p.

Publf c ons, William R. DickinsonPage e5 ght

Graham, S.A. and WRD, 1977, Apparent offsets of on-land geologic features acrossthe San Gregorio-Hosgri fault trend (abs): Geol. Soc. America Abs. withFrogs., v. 9, p. 424.

Ingersoll, R.V., E.I. Rich, and WRD, 1977, Great Valley Sequence, SacramentoValley: Cordilleran Sec. Geol. Soc. America Field Trip Guide, 73 p.

WRD, 1977, Paleozoic plate tectonics and the evolution of the Cordillerancontinental margin, in Stewart, J.H., C.H. Stevens, and A.E. Fritsche(eds), Paleozoic paleogeography of the western United States: PacificSec. Soc. Econ. Paleontologists and Mineralogists Pacific Coast Paleo-geography Symp. 1, p. 137-156.

WRD and D.R. Seely, 1977, Forearc stratigraphy and structure: 9th Ann.Offshore Technology Conf. Paper 2889, Houston, Tex., p. 101-106.

D.R. Seely and WRD, 1977, Structure and stratigraphy of forearc regions:Am. 'Assoc. Petroleum Geologists Continuing Education Course Note SeriesNo. 5, p. Cl-C23.

WRD and D.R. Seely, 1977, Stratigraphy and structure of compressionalcontinental margins (abs): Am. Assoc. Petroleum Geologists Bull.,v. 61, p. 781.

WRD, 1977, Tectono-stratigraphic evolution of subduction-controlled sedimentaryassemblages, in Talwani, Manik and W.C.Pitman III (eds), Island arcs,deep sea trenches, and back-arc basins: Am. Geophys. Un. Maurice EwingSer. 1, p. 33-40.

WRD, 1977, Subduction zones: Earth Science Rev., v. 13, p. 70 71

Packer, D. R., >TRD, and K.M.Nichols, 1977, Memorial to Marjorie K. Korringa,1943-1974: Geol, Soc. America Memorials, 3 p.

WRD, 1977, Subduction tectonics in Japan: Am. Geophys. Un. Trans. (EOS),v. 58, p. 948-952.

WRD'nd W.S. Snyder, 1977, Inferred plate tectonic setting of classic Laramideorogeny (abs): Geol. Soc. America Abs. with Progs., v. 9, p. 950.

Graham, S.A. and WRD, 1978, Evidence for 115 kilometers of right slip on theSan Gregorio-Hosgri fault trend: Science, v. 199, p. 179-181.

Howard, A.D. and WRD, 1978, Volcanic environments, chap. 9 in Howard, A.D.and Irwin Remson (eds.), Geology in environmental planning: McGraw-Hill,N.Y., p. 246-274.

WRD and T. P. Thayer, 1978, Paleogeographic and paleotectonic implications ofMesozoic stratigraphy and structure in the John Day inlier of centralOregon, in Howell, D.G. and K.A. McDougall (eds), Mesozoic paleogeographyof the western United States: Pacific Sec. Soc. Econ. Paleontologistsand Mineralogists Pacific Coast Paleogeography Symposium 2, p. 147-162.

4I'

l

1 ~

~ I s' ~ Xn press, to beHosgri Fault ZE.A. Silver e W.Mines & Geology,

ublished in "San Gregory-.io-California," edited byNewmark, Calif. Div. of

Special Report 137.

The San Gregorio-Hoser i Fault Zone: An Qverv iew

Eli A. SilverEarth Sciences Board

University of CaliforniaSanta Cruz, CA 95064

The San Gregorio-Hosgri fault zone is part of the larger

San Andreas fault system in Cali.fornia. that forms the major

locus of shear due to movement between the Pacific and North

'American plates. An enormous amount of effort has been and

is presently being devoted to study of the San Andreas fau1.t

it elf, and in recent years

offset history, se'ismici',increased dramatically (see

detailed quantitative knowledge of

and present-day'ovement has

for example Kovach and Nur, 1973;

Crowell, 1975; Dickinson and Gr ntz, 1968) .

The extent of our knowledge of other faults of t:he San

Andreas system is much less complete, due in part to the lower

frequency of great earthquakes and smaller offset on subsidiary

faults (and th re fore, perhap, lesser interest in these faults) .

/'Anotl>er reason may be the location of some of the subsidiary

faults. The San Gregorio-Hoseri fault zone is located along the

coastline south of San Francisco for a length of nearly 400 km,

and much of it lies just offshore where it is difficult to

study. Major outstandin., problems of this fault zone include

the det:ails of fault location, continuity between the San

Gregorio and Hosgri f'auld segments, of fset history on each

segment, evidence for Ho1ocene movement:s, and sei. i'oicity, These

1~ ~

~ e 4 I

problems have'mportance both for their tectonic implicationsand their bearing on analysis of seismic hazard. for coastal

deveLopment and power-plant siting.The papers in this volume were presented as part of a

symposium on the San Gregorio-Hnsgri fault zone at the

Cordilleran section meeting of the Geological Society of Am rica, in Sacramento in April, 1977. Not all of those papers. are

'eproduced here but those which follow give a good overview ofthe present state of knowledge of this fault zone.

Clark and Brabb discuss the detailed stratigraphy on eitherr

side of the San Gregorio fault in its type area. Their carefulobservations of fundamental stratigraphic differences, implysignificant differences in sedimentation and tectonic historyon either side of the fault. Graham and Dickinson use this

'I

and other regional data to infer up to 115 km of right lateraloffset. on, the fault since Miocene time. This figure is largerthan an earlier suggestion of SO to 90 km (Siver, 1974) based

on offset basement terranes using offshore geophysical control.~ ~

An estimate of 80 to 100 lan of post Miocene right LateralA

offset on the Hosgri fault (Hall, 1975) ties rather nicelywith the above estimates for the San Gregorio se~ent, but the

Hosgri estimate has been questioned (Hamilton and Villingham,1977). Hall (this volume) briefly addre ses these questionsand proposes a pull-apart origin fox'he Santa Maria basinonshore.

The question of continuity of the San Grcgorio-IIosgrifault zone focuses on four problem areas: Point Sur, Cape San

F-2

~ ~

Martin, .San Simeon, and south of Point Sal (Fig. 1). The Point

Sur region is discussed in detail by Graham and Dickinson.

Their interpretation that the San Gregorio probably connects

with the Sur fault is supported by detailed gravity studies

(Woodson, 1973) and argues against a previous suggestion that

the main San Gregorio fault trace turns inland south ofMonterey to join the Palo C'olorado fault (Greene and others,

1973} .

Hall (1975) first suggested that the San Simeon fault ispart of the Hosgri fault zone (Fig. 2) . The detailed connection

between the Hosgri and San Simeon faults has not been established

and some maps show an 'en-echelon offset between these faults(Hall, 1975; McCulloch and others, 1977) . The San Simeon

(Hosgri) segment trends offshore to the north toward Cape San

Martin (Fig. 2}. Recently flown aexomagnetic data (USGS-Calif.

Division of Hines and Geology unpublished data) reveal a highamplitude anomaly trending northwest across Cape San Martinand seem to require the Hosgri-San Simeon fault either to bend

around the anomaly (Fig. 2) or to step 0 hn inland to a faultbounding the east side of the anomaly. If the fault bends

around this anomaly it could join a major off hore fault northof Cape San Martin (McCulloch and others, 1977} that trends

toward the'Sur fault (Fig. 2). HcCulloch and others (1977)

(their Fig. 2) show a northwest trending fault west of Point

Sur (Fig. 1) which they extend southeastward to the coast;

cutting across and separating the flosgri and Sur faults. This

interpretation would imply a definite lack of continuity between

'

t'e San Gregorio and.Hosgri faults in this area. However,

their northwest trending fault must cross a high amplitude

magnetic anomaly that lies parallel to the coast (anomalyM

bounded by -1.5 nT contour in Fig. 2) and this anomaly shows

no evidence of a crosscutting structure. The anomaly also

trends parallel to the Sur and Hosgri faults and may be caused

by serpentine intrusions along the fault. Structural relationsin this nearshore area are obscured by surface slumping

(NcCulloch and others. - their Fig. 2), and T. conclude that the

bulk of evidence at present favors or at least allows continuitybetween the Sur and Hosgri faults.

The southern extension of the Hosgri is also in dispute.YicCulloch and others (1977) map the fault south of Pt. Argukllo,but Hamilton and Hillingham (1977), using much the same data,

map it no farther south than offshore Point Sal. Either

version raises geometrical problems of ending a fault with

approximately 100 km of late Cenozoic.c 'lateral offset. Uarious

solutions to this problem have been proposed in oral communi-

'cations, including a bend of the fault into the Transverse

ranges where the motion would be taken up in compression (D.

NcCulloch, oral commun., 1977; llamilton and Hillingham, 1977)

or an offs'et of the fault by east-trending faults in tho Santa

Barbara region (J. Crouch, oral commun., 1976) . Satisfactoryfield docum ntation, howe.vcr, has not been reported and thisremains an out tanding structural problem.

Holocene movemcnt., are well documcntcd for the San Grcgorio

faul t (Heber and Iajoie, 1977; Copper smitl> and Griggs, this

1

~ I L ~ ~

volume), and studies of seismicity confirm the present-day

activity on both the Hosgri and San Gxegorio segments (Gawthrop,

3.975 and this volume) . This information is critical to any

planned development along the central California coast because

the San Gregorio-Hosgri is very nearly a coastline fault over

most of its length.

. The San Gregorio-Hosgri appears to b the'argest of the4

subsidiary 'faults within the San Andreas system, both in length~ and offset. Other faults, such as the Hayward-Calaveras and

Rinconada have lesser documented offset but also play an/

important role in the tectonic development of the Californiacoast ranges and are deserving of intensive study.

F-5

References Cited

Crowell, J. C. (Ed.), 1975, San Andreas fauLt .in southern

California: California Division of Hines and Geology

Special Report 118, 272 p.

Dickinson, W. R., and Grantz,, A. (Eds.), 1968, Proceedings

. of the conference on geologic problems of San Andreas

fault system'Stanford Univ. Pubs. Geol. Sci., v. 11,

374 p.

Gatothrop, William,'975, Seismicity of the central Californiacoastal'region: U.S. Geol. Survey Open-file Report 75-134,

87 p.\

Greene, H. G., Lee, V. H. K., McCulloch, D. S., and Brabb,

E. E., 1973,. Faults and earthquakes in the Monterey Bay

region, California: U.S. Geol. Survey Misc. Field Study

M.F. -518, 14 p.

Hall, C. A., Jr., 1975, San Simeon-Hosgri fault system, coastalCalifornia: economic and environmental implications:Science, v. 190, p. 1291-1294.

Hamilton, D. H., and Willingham, C. R., 1977, Hosgri faultzone', structure,. amount of displacement, and relationshipto structures of the western Tranverse ranges: Geol:Soc. America Abs. with programs, v. 9, no. 4, p. 429.

Kovach, R. L., and Nur; Amos (Eds.), 1973, Proceedings of the

conference on tee t.onic problems of the San Andreas faultsystem: Stanford Univ. Pub"- Geo'L. Sci., v. 11, 494 p.

HcCulloch, D. S., Clarke,'. H., Jr, Fic.ld, H. E., Scot t, E. W.,

F-6

'l ~

~ l ~ ~

~'7

W

and Utter, P. H., 1977, A summary report on the regional

geology, petroleum potential, and environmental geology

in the area of proposed'ease sale '53-A, central and

northern California outer continental shelf, part A, 39 p.

Silver, E. A., 1974, Structural interpretation from free-airgravity on the California continental margin, 35 to 40 N:

Geol. Soc. America Abs. with programs, v. 6, no. 3, p. 253.

Weber, G. E., and Lajoie, K. R., 1977, Late'Pleistocene and

Holocene tectonics of the San Gregorio fault zone betweene

Moss Beach and Point Ano Nuevo, San Mateo County, Cali,-fornia: Geol. Soc. America Abs. with programs, v. 9,no., 4, p. 524.

~ Hoodson, N. B., III, 1973, A bottom gravity survey- of thecontinental shelf between Point Lobos and Point Sur,

California: Thesis, Naval Postgraduate School, 112 p.

-8-1 ~

Figure Captions

Figure 1. Hap of central California coast showing geographic

„ locations and faults cited in text and location ofFigure '2.

Figure 2. Detailed aeromagnetic map of central Californiacoast between Point Sur and San Simeon. Flight lines

4

had 1 mile spacing, flown normal to the coast.

F-8

~ ~

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~ 0

Son Francisco'

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a

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Cape Son Martin~"'.:.:,

San Simeon '-:. ~q

~

~~O -"~: Oy~

P )Figure 2,

:,SantaPf Sot "MarIa

:Basin:;:.'. Tra nsverse Rong esPl. Argualla "'::.:,~

""::.:,,Santa,:,

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35'30'6uMorih

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The San Grcgorio-Hns ri fault t(cndparallels the central California coastfrom its inter'ection svith thc San An-dreas fault nor thsvcst ofS;m Francisco tosouth of Point Sal (Fig. I). In this rcportwe prcscnt on-land gco!Ogic cviJcncc forabout I IS km of ri ht-lateral strike slipon this complex fault zone. On-land andoffsliore segments of the fault trend arcwell defined by geologic mapping andmarine surveys (I-I). Conn'ecting linksremain controversial, however. whereinferred through shallow water in coastalzones where acoustic protiling data arcabsent or ambiguous (5-7). Ncverthc-

80

GUAI.ALABASIN

KM

0

BOOEGA NEAO

PT. REYES

less. chance alignment of »cveral wcll-dclincd ni;Ijor falilts»cern» Iinlikcly.

Fur»'hcrmore,ifour evidence f'r right slip onthc fault trend is valid, throughgoingcontinuity of thc, fault zone is required.

Thc evidence for right slip consists ofscvcn pairs ol'tl'»et geologic fcl(turcs(Fig». I and 2). Yonc of thc»c are indi-vidually unequivocal. hut t:(ken togctlierthey present a compelling argument.Linear geologic and palcogcographic fea-tures forming piercing points on t'liultplanes are the mosi sensitive indicatorsof strike slip (S). Certain of the oil'sctpairs listed bc!oiv arc lin ar features. butunfortun:itcly nunc are tightly con-strained. Conscqucntly, we show prob-ablc offset ranges. Thc common denomi-nator of I IS km (Fig. 2) is our estimate of

~ right slip on the San Gregorio-Hosgrifault trend.

Details ot'he offset geologic featuresare prescntcd clscsvhcrc (5, 6), but insuminary they include thc I'ollowing.

I) 7%e 8udega-Gaalala f(n(l(-Pilar-ci(os f(n(l( oJJse( pair (asterisks in Fig. I).

Ga7(7~10-J t(7.'„.'ll!rif(nil((r«n(l Is a ('n(po(i('n( offl(('an vIM(If«as

fa((I( sys(e(n un >a%i<% (l(ere nn(l'n(v('>een «lnn(( ILS Iilun(((mrs of pos(-I'arlv. hlioeene rigla-la(( r«l s(ril e slip. Ifs«. rig%( .clip on (I(e San r'hodr«as «n(l San Gre-

gurio-Ilosgri fanl(s «t roan(s for n(os( of (l(e niui'ennva l>e(>veen (I(( I'<((ific'aniI>,'or(II An(eric«a pla(es .since n(i(I-hliueene (in(«. Irnr(I(ern(ore. (IN'M(gnila(le ofrigl(( slip on a P((leog('ne pro(a-$ «n Anclreas Jin(l( i«Jc'rrecl fr>nn (I(i pris('n( elis.

(riha(ion ofgrani(i« l>ase(nen( is r((la('ed ('ansi(l( rallly u%en A>«ug(n«-R«e(n( San'regoriu-II«Ig(i rigl(( .clip is (al'en in(o «ceunn(.

~III>>CIIV»liiilllIs iul ar>:Illuollc(I iulce»tral »tr;ind of the S:in Andrca» faultg9). Although lying svc»t of thc inodcrnSan Ainlic:is fault. thc I'ilaicito» fiultthus i» thc local »tructurd boundary l>c-

tsvccn I ranciscan Complex on the north-east:ind granitic basement on thc south-wc»t. This prc-Slin Grcgorio f:uilt maybc nn'sct to the north a»';in int'err«d»truc-tural contact scpar;iting thc north-ernmost granitic basement outcrops atBodega Head from thc Franciscan-floorcd (?) latest Cretaceous and 'e;irlyTertiary Gualala b;(sin ivcst of the SanAndrcas fault (/0).

2) I'O'In( Reves sec(ion-Den Lun(on(Ihloan(ain sec(iun offs«( (x's in Fig. I).Distinctive Tertiary sections, includingunconformity-bound p;lcl'ages ot I'i(lco-cenc, middle Miocene, and upper 5(io-ccnc-Pliocene age. as well as com-parable granitic basement. occur at PointRcycs and Bcn Lomond Mountain (II-I3).

3) Pigeon Point Fora(a(ion-San(a Lu-cia Cre(ac«o((s uJlset pair (A. s in Fig. I ).

Upper Cretaceous deep-sca fan depositsof thc Pigeon Point Formation (!4, /5)and an associated Cretaceous basin m;ir-gin (6) are probably ofl'sei from similarfcaturcs in the Santa Lucia Range (6). Inaddition. preliminary studies sucgestthat Oligo-I>liocene shallow- to deep-ma-rine facies overlying the Pigeon PointFormation (l6) may have offset equiva-.lents in thc Santa Lucia Range (5).

4) OJfse( uf ogsl(ore ravi(v ridge(Fig. I). Silver (17) proposed that a lineargravity feature offshore from Ano Nuevo

SFB

Pl SAN PEORO

PESCAOERO

PIGEON PT. $)FhiAN0 NUEvo PT.qBEN L'OMOMO

AT N.

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(LARCITOSFAULT

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FRANCISCAN~ S 0CONTACT ~

SAN SIMEON

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l35

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IPOINT REYES IBEN LOMOMO

OFFSET

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A>70 MUEvo-SUR OFFSET

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OFFSETINALLI

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200KM

300ii KM WI''>

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I.ATERAI pos!TloNS or- oFFsET MlopolNTSALONG SAN GREGORIO- I.IOSGRI FAULT

Fig. I ttcf(). S I:>(> uf Bcutnuie fC:>lu(cs Ull'ic( in a right h>(crit »CI>iC along ihc sh>n Grc('<>(h>-II(>iI:(iIhi>li I(CIKI. Scc teal fa>'(liicuii>h»I. I(ig. 2 triuhlh O(l'sct range clni(t f»r SI>KI'col«lI>il'»ct I». iis ih»>v(I in I>ig..l I>(I>I di»c«i»c>I in Ihc text.

(Kl'l(>.t(U75(7KAI(I 1 I>(795(>I).5(VII C»Py>ighi C IV(K hhhB

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~ ~

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PRC SCNTNQRIWRN IIHTtYSALON diSCNCNT

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PACIFIC N. AMERICAN PLATES(RTNATCR d NDLNRR> ISTS)

n

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~ ~ ~ ~ ~ > ~~ ill+r

PROTO SAN ANDREAS o t IMOVEMENT ON

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SAN GREGORIOACT>VIT Y

PROTO-SAN ANDREASMOVEMENT IM'X)CONSIDERINGSAN GREGORIO FA>f~T

10 00 Co 10 00AGE (MYBP)

OTHER FAULTS MOVEMENT (MAX)DISREGARDING

POTEtitlAL CUMULATIVE SAN GREGCRO IrINDISPLACEMENTSAN ANDNEAS SAN GREGORIO

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ONn

II

h0>&CRN VwT Dr SRLR><ANSRSCNCMT R(STC NS NCOXICSCN AhCRCAS d $AN ~~ltQVClcCNT

:1T'/TTIPOLC TIN>0 SAN AICACASDTTSC'I

I

LFRQQASLC LI>OT &SCITIAN OASC+CNT

Fig. 3 (left). Northern limitOf'Salinian block after restoration ofNcogcne right slip on theSan AAdrcas fault alone (A) or on thc San Andrcas fault plus the San Grcgorio.HOsgrifault trend (0). The remaining o(Tsct of gnnitic b:iscmcni noi accoun(ed for by Neogcaeright slip may be 0 measure nf right slip on 0 pro>o-San Andreas f:iu(1. Fig. 4 (Tight).(Curve A) Time-Of)set curve ((2) mndi(lcd tn Show the e(feet of San Ctcgorio-Hi>sgiright slip. (Curve 0) Relative motion of the Paci(ic and North American p(ates (33). See

text for discussion.

Point is the offset expression of thc con-tact between Franciscan rocks and gra-nitic basement of the. Salinian block inthe Santa Lucia Range.

5) Point Snr ~ Francisran-CarnhriaPines slab nfJset pair (underlining in Fig.I). The Fr~nciscan subduction complexof the central California coast is general-

ly a potassium feldspar-free mctascdi-mentary sequence (IS, -l9). Exceptionsto this gcneraliza(ion arc structuralblocks of potassium feldspar-bearinggraywacke-shale at Point Sur and Cam-bria (IS, /9). These tivo blocks:ipparcnt-Iy have been offset by San Gregorio-Hosgri right slip.

6) Point Sar Itliaeene sarttlstone-Frarteisettrt sttnree terrrtne <>/set pair.hfiocenc s:indstonc occupies u sn>nll

fitful( sli«c ivithin the Sur fault zone seg-ment of thc San Grcgorio-flosgri faulttrend ne;ir Point Sur (5, 2tI). Dcspi(c theImn>cifliltc pl ox>A>lty ol I'.r;lni(ic b>I!ic

nlcnt cxpi>hcd iA hliocct>c (talc (5). (hcs;>Add(one h:lh 'till cxcl>>SILL'ly I'rilllc>si:allprovenance (5). At lc;ih( 60 ktn of rightslip i» required to proviilc an adequateI'ranciscaii source tcrranc. 'I'hc ol)'sct

cannot cxcccd l05 kn>. hoivcvcr, bc-ci>u<c th» silllds(ot>c I'l.ks vole>it>lc cli>s(s

typic;il of htioc«nc si»>>(Stot>cs near('>mbri:> ( I ). Tlic Ii>L'k ill ovLI'liip ofLII)hct bc('ivccli Ihc I i'I>At Sul'i>oct!Ac) inifs(L>nc anil otl>cr otl'hL I p:iirs (I'ig. 2)LILTCS t>O( LIL'lL"it(hc ollhCI Ill'i',lllni;AI,bcL;iilsc (hi; Miocct>c tai>llifh(oi>L'h ln a Iilul(

slice incorporated in the f'ault zone at anintermediate distance.

7) San Sinteon opltiolite-Point Srtloyltiolite offset pair (double umlerliningin Fig. I). H ill (22) reported the probableoffset of a ihfesozoic ophiolitc and anoverlying"Per(fary sequence from PointSal to thc San Simeon area along theHosgri scgmcnt of thc fault trend.

Displaccmcnt of the Point Sal-S;mSimeon ophiolitc association along theHoscri scgmcnt occurred 5 to l3 millionyears ago (22). Other of)'sct indicatorsdemonstrate post-carly Miocene andprobable post-middle Miocene right slip.Holoccnc movcmcnt is documentedfor onland and oA'shore fault scgmcnts(2~)

Granitic b:iscmcnt of'hc S:ilinianblock west of (lie San Andre:is fault isollsct by >I A>inii>>i>11> of 5 lt) kn>. biiscd onnor(hcrnmost granitic cxposurc» at Bo-deg:> Head (Itig. I). Ifgranitic baden>cntextends o(l'shore to I'oint Aren:i (2 I). thcmaximun> oil'sct i» 600 km (Itig. 3). Rcs-torition of'vcll.documcntcd post-Iiv-ccnc San Andre;is right slip ol'05 kin(24-?6) brings thc»orthcrn litnit of

S:ili-'i:in

b;iscmcnt h:ick to position A in Irig.3. Tl>c dill'Lrcncc bctivccn position A(Itig. 3);inil the no) tl>ivcst liit>it of Sicr-riln lu>Ken>cut h;Is bccn ttlkcn;Is;I n>i'.,'I~

)dirc ol'rc-I occnc "proto-8:>I> Aii-ilrc:is".right slip (27. '8). ()Ilier rLI(ioi>alcviilcncc pk>cch (l>is ilcl'orni:>(ion in I';I~

lciiccnc titnc (5. 29). I loivcvcr. thc ILVA(o.

G-2

I

ration fails to consider the extension ofSalinian basement by! 15 km of San Gre-gorio-Elosgri right slip north of its inter-section with thc San Andreas I'ault (22. p.f293)r Thc restoration of this additionalI I5 km of'Neogene to Recent right slip toposition 8 (Fig. 3) reduces by one-thirdor perhaps two-thirds the apparent right-slip of)set of the northern limitof the Sa-linian block by the supposed proto-SanAndreas fault. Furthcrmorc. in thc un-likely event that the limitofSicrran base-ment actually lies to the not th in the sub-sud;Icc (30), And if Bodcga f lead is nearthe northern limit of Salinian graniticbasement. then a proto-San Andreasfault is prccludcd along the modern SanAndre:>s pathway in central California.In any cvcnt, thc proto-San Andreasfault app;ircntly Lvas not a transformf;iult:in:ilogous to thc modern San An-dre:is I'aiilt system. Instc:>d. proto-SanAndre;is f:iulting may have been thc geo-logic rcsohttion of oblique subductionalong thc central Californi:icoast in ciirlyTcr(iary time ((I).

Righ( Slip of'hc S;m Andrcas fault isco ave Alen(ly iflhpkIycif;I',I;I Iln>L"illsplaccn>cnt plot on curve A in I'ig. 0 (.'.).Thc ilottcd n>1>dili«;i(ion nl'curve A priorto 60 Inillion yc:Ir» ago shoivs the c(l'Lc(

of disrcg:>riling S;in Greg>irio-I lohgririgl>t Slip in proto-S:>I) Anilrc:ih f:Iult in-tcrprc(:itious. Curve ll in Itig. I shi>>L>

Ihc I eh>(lvi: lnovL'AIL'}ltlic(ivccn (lie I,iI'>Ill ilail Ho> (h Anil,>'lean pkl(cs (I )

SCII:.NEI:.. Vot.. Iv)

i~ ~ ~ i

SYithih the iinccrt:<inty of Ihc curves,(AOSt n<OLCIACnt lv«tLVCCA tlic platCS l)AS

bccn loe:ilircd;ihuig (lic S;<n Andic;i»fault proper I'vr thc lait 6 niillivn years.Bctsvccn th;it (imc:uul thc c;irly caIio-

ccAc, A<As( of tile pl<it« Ill<1(ioA was illstriivu(«<l bc(LLC«n thc S;<n Amlrcas:uidSan G<'cgorio-Ilvigri f;iult trends. Ti<us

thc prcscnt extcniion of granitic bi<ce-

ment of thc S;ilinian bio;k in I:irgc part isexpl'<incd by right slip on f:iults of thcNcogenc Sin Andre:is (nuit iyitem, as

suggcstccl hy Johnson and Worn«:rk (34).S. A. QRAHA>ct

Frplns csfios< Drparlsnrn(, 11'c sternRegion. Chevron U. <.e'L. Inc"a,

San Fs'csssciscu. Cc<1%rssics S)4I /9<<Y. I(.. DICKIHso~

DCp«fin< ms OfGC'OIOJLV. SICSS<fs)rcl

Univcfsily, Sf«<<ford. California S)4305

3-d:iy period on hnlns milk. Never-(~8, pilp!i of <ill clgcs Lliiplclyfcililcc,'cl%)%fit;1<NI ILip Ll<cvcloplncnt Lvllcli,nursed on I«sin) milk.

ln an attempt to dc(ciminc thc caiiscof dc;ith. tissue sections from.thc af-fcctccl pops werc cx:imincd histolvgi ~

cally. Thin sections of skin. lung. liver.stomach. bone. and muscle werc pre-pared fron) ((-d;<y-old pup» nursed onIsnlns milk. The sections were st;iinedwi(h hcmatvxylin and cvsin and examinedunder tlic light microscope. Only thcskin appc;ircd abnnrnial, displaying. fvcal;iciltc clefill;ltltis, gcllc.'I",ll Ulldcfclcvclopment. and I'olliclcatrophv. FL<r(hcrmvrc,thc str itum gfanulosum w'is signific;intlythickened and the number of hair sh;if(smarl'cdly reduced. All other organs ap-pearccf nor<nal. though undersized. andno cvidcnce of infection, allergy. or in-complete digestion of milk was „ob-sc<'veil.

Histological observations ivere alsomade of mammary glands ot'n)los d;imswhose pups were'close to death. In gen-eral, thcsc glands appeared less activeand smaller than (hose of normal 8/6mice. Moreover. we observed that Is«iso

dams frequently yield less milk.Tal'en together. these symptoms are

similar to those described by l<Iutch andHurley (3) in rat pups nursed on dami re.ceiving a postgestational zinc-free dict.Thi» dict leads to a so percent decreasein the zinc content of the milk by day ISof lactation, with only minimal ctfects onthe other constituents. As a result. nurs-ing pups a'e severely depleted of plasmazinc. 1 Lvo-thirds of such animals die a<Hi

all exhibit retarded grow(h an'd severedermatitis. Nloreovcr. total milk produc-tion was reduced hy 50 pcrccnt in thczinc-dcficicnt dams.

Bcc;<L<se of the similarity of symptomsbetween thc dietary-induced zinc dcfi-cicncy and the lrflusl«sill'yndrome, wecompared thc concentrations of zinc inthe milk of Inihn and normal mice. Asshown in Table I, the zinc content of thcmill'l'utant mice is reduced 34 per-cent from that of normal B/6 mi«c. Thisdill'crcncc is scen thrvugliout lactationand is rc(lcctcd in thc whole body zincCOnC«ntratiunS Of S-clay-VI<chil( is<siss< Ic:A1«lciexhibit norm;il conccntr;i(iong OI'ot;ilhvdy zinc. it:ippc:<rs (hat the mut:iticiiiinvolves re<inc«LI trini(ort o('zinc frompi'<in«: I<1 <liilk. I hc It.'6 d:in<8 niaint:ii<1;I2<ii« co<ieciitfatlon iu thc «iilk tliat ii tcntliilcs h<1',tie<'tlilil thilt isl Ill« plilii:li<

right 0 197>8 AAAS 1st

J, C. Clack. disc«<<a<ion. Stanfoid t<nivccvi<y(1966).I), C. Rove. U.S. Grul. Sun.. I'rc>f. I'cip. 698(1972).I, C, Cro»c)l. Grul. Sac; Am, Bull. 68, 993(1957) ~

U. R, Lowe, Ivoc. 24<h Ins. Crnl. Caner. 6. 7S

(1972).J. C. C)ack a<ad F.. E. Rcahh, C<rlif. Div..<(InesGrcil. Sprr. I'c p., in prese.E. A. Silver. (irc>I. Sc>e. Ani. Ahssr. P<c>gsccrn c 6,253 (1974).W, Giihcc<. Ca'<il. Sor. An<. Bull. 84, 33)7I)973).

. J. ) (su, C<r!i% Dias .Ltfnrs Crul. Sprr. Rc p. JS(1969).P. D. Track. Bus(. Drp. Groi. Uni '. Culif. )3.) 33 (1926)C, A. Hall. Jr.. U.S. <7ruf. Srrcv..<fisc. FieldSr<cd.,<fup .LII'L'9((974).

, Srirnc'r 198. )29( ()975).F. A, Silver. J. R. Cue<ay. A. K. Ca>per. inG „(,gir Gui Ir s n. Crrir)i>micr. J. Il. I.ipps;indF,. h(. h)oores. Fdc. (Geological Sa>eic<)i Savca-men<o. Calif,. 19 ~ I), vo(. I. pp. I Ii<.

W. R. Uickincon. D. S. Cowan, R. A. S«h»cick-cc<.Anr. Ass<>'. Pc's. ( r i. Bn<S. So. 3 c(l91 kV. h(a<<hews. I(t. i)ii,f. 60. 2128 (1916).T. H. Hi)scn and h(. )I. Link. in I'ir<c<ieriirSvuipusiun<. D. W. Lvcaver. G. )In<no>lay. *.Ti(><a>n, Eds. (So ie<y of Economic Pa<«on<o)-

ogas<s and htincca)aig<c<s. Tulsa. )9151. p. 367.J. Suppe. Crul. S<>ai Acn. Bull. Sl, 3253 (I'9<0).R. W. Kic<)cr. Z. F.. pe<«<man, D. C. Ro». D.Go« fcicd, Ssanfurd Uma. Pabl. Grot. Sci. S. 339((973).For csamp(e. scc S. A. Graham. Iv'ra«mr Svrn-posiuni.*. E. Fri<vche. H. Tcc Bes<. Jr.. W. LV.Wocn:<cd< ~ Eds. <So«ia<y of Economic Pal«un-co)ogii<s and ~1(nccatogis<s. Tu)sa. 1976). p.125.Sec ihc du«cd linc in Fig. 3.P. J. Coney. Grus. Sor. Am. Sprr. Pup.. in

cecce, Iodificd from chc cucves of Diekinconrc al. 124)and Hclven and Link <26) in ac«ocd.ance wi<)i ahtiocenc Plio cne boundary near 5 million ye.icvago. (roc a de<ail«d div«ussion scc Graham <5<.

T. A<wa<cr and P. 81o<nar. Ss«nlurd Univ.,Pub(.Grus, Sri. 13. 136 (1973).I, D. Johnson an 3 LV. <Ho<mack. Grolngy 2. I I((914).Our ccveaceh was supponed in part by the EarthScience Sec<ion. National Science Founda<ion(gian< UES 1=01728).

htay 1977; revised 22 Augusi 1977

16

17

v0

2123

1516

References and!Co<es '>7

28I. A. K. Cooper. U.S. Crul. Su<v. Oprn FilrRrp.

I901 ((973). p. 65.2. G. E. 'Wchec. Geol. Soc. Am. Ahssr. Programs

9. 524 (1977).3. H. G. Gc cne. LV. H. Lee. D. S. 8(cculioC. E.

E. Bmhb. U.S. GrnL Sun..'<fisc. Field Scud.hfnp <IF;<I8 11973)

4. H. C. LVagncr. U.S. Grol. Srrni Open FilrRrp.(1974).

S: S. *.Ciiaham. diss«<<a<ion. S<anfocd Univccsi<y(1976),'p. 5)0.

6. and W. R. Dickincon. Calif Div..ifinrsGros. Si>rr. Rrp., in pccss.

7. E. A. Silver. Ga ul. Snc'. Ain. Ah<sr. Progranis 9,500 (1917).

8. J. C. Cro»eil. Gros. Soc. A n. Sprr. Pnp. ll(196 ). p. 61.

9. for ecamp(e. sec T. H: Ni(ven and T. R. Simon(.Jr.,J. Rcs. U.S. Grnl. $«n. l. 439 <)913).

(0. C. ht. LVcm»ocih. Ssunfi>icl Univ. Pabs. Geol.Srf. I (. (30 ()968).

1(. A. J. Galloway, Calif. Div..<finrs GroL Bull.202 ((977).

19

3031

32

33

35

23

Zinc Deficiency in i<<furine IXIilkUndcrIics

Expression of the LeIIIal(7<1'ilI'IIII)iver((t:((ion

A rcccssivc mutation. designated le-(lail nsill'lns). Lv:<8 diicovcrcd a<nongniigc of thc CS"sIIL'6J (l)I6) striin (I).Pups nuried on i«ilia d:iin» exhibit stunt-cLI groi'vill,;<elite <le<'ill;lli'Ils, alopcci;1 ~

and Llc:ith prior to Lvcanin„. Since normalBI6 pupi (I.nsl.ns) dic rvhcn nuricd onIn<los inilk, (lie clcfcct rciial«i in(hc milk.I lvlcoic<', linln< pi<ps dcvclc'>p tlol'<ll;illyif fiiitCr-nuriC<l Vn;i AO<in:il Clam. (.>C-

nctic 'in:ilyiciinalic;ite tliat lns ii loc:i(cdVll L'hi'La<llviO<11« (<lid ill l(si ),6 \:el<(inlol'I'„ini lio»1(lic;igooti hs) loci<i.

I llc cllccts La( lssslsss I<Ill(i clll 1<a)who<ii

pups pcriiit at AII i(ages of lactation (2).a<Ye, h;<vc evnfircncd tlmt ncvvborns fv»-tcrccl on lnslns dan<8 'it mid-lact;itinn orI;i(c hie(:<(ion;irc ai s«vc<'c'.IV <itl'a.'cled iis(I<use All<'i«LI(fL'<1<1 (lie beg<An<A<: of I;<c(il

lion, In;<clclition, Lvc have foun<I;1 Llif-

fcfcACC ili husccp1<l'ail<tv tv thc c(lects vflnslsn <<<ilk cvith rcip«ct tv thc <)'.c

OI'i<pi.>i(owl<of<i pl<ps;<lc.'f<'cvcfillslyco<An<i(teil to if«1<th:1('Icf 3 d;<yi on In<los

A<ilk. cvcii wh«ii siihscquvntly tfani-(L«ccl I«:i iio«»:il .I'cni. ()hler piipi, ontli«otlici li;iiul,Ii;iviiigniiric<l oii in g«)ss7<LS) l)J uu<(s<>a<.5<L'0 (:opySCII!h<CIL YUI.. IV'S, IJ JA'St<A)tv )><78

Abstmct. Tlsr inahilisy c>fnursing pops Io sorvivr an sssiII'f nss'cc I<os<so-i'gosss forIhe rc'ccr rivr'nuslali«n. Icth il milk (Im).is ccsrrrlalrd i«ills a rrclocfian in -issc levels ofboll< ss<ilI'ncl pop carcass. rlcln<inislrasiou of -ini's pnps ssssrsing on Imlm.cl«nssrrdssccs Iln'lisrrvc'cl snorsalily «ncl ssusrbsclilv. II is saggc'sfrcl lhnl Im «l(crs -inclransporl freon nsafc rsusl l>lci<icl scs sssilI; «ncl slscss ii.r ssssclynusy proviclc'srfssl infarnsa-

c

lionfor unclrrssanding slsc'are'susnass disease, cscrridcrn<afisis rnlcropashic'«.

G-3

~ y

~,

4 ~

Roprinlcd from'6 Docombor 1975, Volumo 190, pp. 1 l 294

San Simeon-Hosgri Fault Syhten), Coastal California:Economic and Environmental Implications

The San Simeon fault terminates theArroyo dcl Oso fault, which cuts throughthe lower part of thc 12-m terrace (l. 4).Thc Pl«istocenc terrace deposits within theregion arc 130,000 >30,000 and 140.000

+ 20,000 years otd (5); therefore thc Ar-royo del Oso fault is younger than approx-imately 130,000 years and, at least in part,thc San Simeon fault must be s(ill younger.An epicenter (date unrceordcd) is locatedon the Arroyo dcl Oso fault and thc mag-nitude of the earthquake is reported tohave been bctwcen 4.0 and 4.4 (6). Holden(7) reports earthquakes of 26 October or26 November 1852 and I February 1853 atSan Simeon, where "houses were injured.nHowever, the authenticity ol'hese early

Abstract. There has been 80 l'ilomerrrs or ntore ofright slip along the late I7unIernarySan Simeon-llosgri faulI sysrem of caasral California during" the last 5 Io 13 millionyears. Parr ofan oil-rich basin is Probablyogser by this fnulIsystem, and Iht'sysrcm maybe a potential ha:ard Io nearby slrucrures.

Comparison ofstratigraphic sections ex-posed on opposite sides of thc late Quater-nary San Simeon-llosgri fault system atPoint Sal and near San Simeon (Fig. 1)strongly suggests large-scale lateral dis-placement. Thc nature and agc ol'trikc-slip displacement along the fault systemhas important economic and environmen-tal implications, for it suggests the possiblelocation of an ofTshorc extension of the oil-producing Santa Maria basin and indicatesthat thc system poses u potential hazard tocngincered facilities.

Thc San Simeon fault in coastalcentral'alifornia,first named in 1974 (I), can be

traced on land for a distance of approxi-mately 19 km-that is,'rom Ragged Pointto San Simeon Point (Fig. 2). ln the areaoffshore from Ragged Point, Hoskins andGriAiths (2) show a 65-km northwestwardextension of thc San Simeon fault. Silver(3) reports a fault with as much as 5 km ofdip separation in the olTshore basin southof Point Sur (that is. 80 km north of SanSimeon), whi«h may bc thc northern exten-sion of thc San Simeon fault. The SanSimeon fault may also extend farthersouth from San Simeon Point to nearPoint Estcro (Fig. I) in thc utTshore, aspostulated by others (l). Such a suggestionis supported by the fact that the coastline isstraight and rises abruptly from the sea.

Near San Simeon Point the trace of thcSan Sim«on fault is concealed by latePleistoecnc or Holocene slightly cementeddune sand d«posits. lt faults the 122-mPlcistoeenc terrace approximately 5 kmnortheast of Point Pi«tlras Slaneas, butdocs not eut the 12-m terra««near eitherSrcaker 1'oint or Ragged 1'oint.

The Arroyo Laguna fault (Fig. 2) is be-lieved to be a relatively >ounger and morcrecently active strand ol'he San Simeonfault zone. This fault is m:irk«J by a pro-noun«ed lin«ar valley north of San Sim«onPoint (4), hy a 75-m fault s«arp, and byfaulting of the 122-m Pleistocene t«rracc.The fault crosses s«v«ral west- or south-west.draining canyons, including Arro>ollondu. Arroyo dc lus Chinos. and three

other unnamed canyons between Arroyodc los Chinos and Arroyo dc la Cruz (4).Each canyon is marked by right lateral de-viation of 150 to 450 m: however. the faultdoes not juxtapose markedly dilTercnt rocksequences or types (Fig. 2) as docs the SanSimeon fault.

'.~co

Cooo Soo MofloI

o+

ROSSOO Pt

ooV ROCOOI TZ

Pl &44oo Bloncoo I»B4II~ ~oo 54oooo

Soo SnoOOII PI Polo Rootoo0eo

COolnooILov,p oop

oQPl fOI~IoCh Xo

TI l OOvMonoBog r

ollaPl Soo LIoo

o

ClY,

t

Vr

ovoo

oCg

oo/

C)

ca

XnOIOBronco Orv

hot

;O

I OI0 lO oIIloo

Ponoono Pl

Lonooc

Pl AIOOOOO

Pt Concooloo»»

MooLOCOInoI

1 Bio

I'ig. I. Location ul'ihc Sun Silo«un I lutgri fault system. I)use mup ic frnui Jennings I I I) un J severalut her sources (I.Z. 4. u. IO. 13).

inputs

inJ it~tc hypuhyxs ll plugs of the blur la Itu«k - Islay I lillturn.plex (I, IO, I7).

earthquake reports has been qucsti(8).

Thc San Simeon fault tcrminatcs thcO«cani«IVcst lluasna-Suey fault system(Fig. I). The IVcst lluasna fault may tcr-

.ntinatc thc )idna fault (9). which in turndispla«cs I'Icistoc«nc anti late I'I«istoccncdeposits (9). Thus, although mov«ment be-

gan carlicr, probably bctvvccn thc lateMioccn«and late Plio«cnc, th«San Sim-eon Iault must be Plcistoccnc or younger.and strands or associ tt«d faults may bceven younger.

Thc Hosgri fault (l0), also called thcEast Boumlary fault or fault zone (I), ex-tends southeastward from near PointPiedras Blancas to near Point Sal, butsouth of Point Sal thc continuation is notclear (II). Seismic reliection records (I,l0) show that there has been dip separa-tion, with thc west side moving down rcla-tivc to thc cast side. Di}Tercntial movcmcnt

'has oc«urrcd intermittently along thc Hos-gri fault from late Miocene to Holocenetime (I). Earthquake cpicenters along the

~ ss

Thc rocks in thc I'oint Sal area haveccn d«scrih«d Ity IVoodring and

llram-'as

h«cn d«scribed hy I lopson «r al. (I5).Thc old«st rocks in that ar«a arc those ofthe Jurassic (~ l60 million y«ars) ophiolit«,which consists of a lower part of s«rp«ntin-itc. layer«d ultramalic ro«ks. and gabbro:and an upp«r part ofdiorit«. quartz diorite,a dike and sill complex, and submarine pil-low lavas. Greenish-gray tulTa««ous radio-larian chert, overlain by Jurassic shale andsandstone. r«sts on thc ophiolitc complex(I5). A similar sequ«n«c of rocks occursnorth ol'S;m Simeon (I'ig. 2) between theArroyo dcl Oso and San Sim«on Iaults,but thc lower part of thc complex prcscntnear Point Sal is appar«ntly ahs«nt, as arcthc submarine lavas. in thc San Simeonarea.

A Jurassic ophiolitc cast of'Ivlorro Bay(13. 16). cast of the San Simeon fault, andin relatively close proximity to San Sim-eon, is overlain by rcd radiolarian chert,not thc distinctive greenish-gray tu(Taccouschert west ol'the San Simeon fault.

Thc Franciscan shale (Fig. 2) in the San

fault suggest tllat lt could hc sclsnllcall~active (I, IO, l2). Arpuntcnts supportin~aml refuting th«possiltility of strike-slip lcttc (/4) and. morc rc««ntly, tile opltiniitc

'novcmcntalong thc llosgri Iault havebeen caret'ully r«viewed (I); how«vcr, newdata present«d herc strongly suggest thatthc San Sitncon and }losgri faults arc partof thc same syst«m, right slip accountingfor thc distribution ol'urassic to Plio««ncrocks.

Recent geologic mapping near San Sim-eon (4) and thc area b«twccn Santa Mariaand Snn Simeon (9. I3) (I'igts. I and 2) hasshown that remarkable similarities existbctw«en rocks west ol'he San Sim«onfault zone, nc:tr San Simeon,.and cast ofthc I losgri fault near Point Sal (Fig. I). Ju-rassic ophioliti:, ovcrhtin successively bytulTaccous radiolarian «h«rt and Jurassicshale: Oligoccnc nonmarine conglom«rate,associated tutf, and distinctive landslidedeposits: and later Tertiary cherty shale

ol'imilarcomposition and histories ar«oIT-sct (Fig. 3). The horizontal slip componentmay bc SO km or more.

SueS~

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I

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E

L

stooge I.'lie'e "", Q s

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ee~ss

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eo

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eeeoesese

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ISI IS

Fig. 2. Prc.Quaternary gcotocic mup shnwinc distribution und stratigraphic relations of the Jurassicophiulitc, chert, ural sbutc scqucnw.: thc Oligocene l.o»pc I'ormatiorn und ltluntcrcy Shale near SanSimeon, California t4). This mup should bc compared with geologic maps of thc Point Sut-t.ious}}cud urea (/4, IS), where thc Luspc Formation ovcrlics the Jurassic ophiolitc uud shale. The ru«ksin thc Sun Simcun }tointurea would have been ut least l2 knt otfshorc from Point Sul prior to movc-mcnt along thc Sun Simeon-} losgri fault system.

Simeon area consists of'dark greenish-grayand brosvn weathering clay shale. The unitis lithologically similar to thc l.londa For-mation ol'ibblec (IT) south of Point Sal,but it is not recognized in the Santa Mariaarea; it is presumed to lie vvithin thefault block northeast of the San Simeonfault.

Jurassic shale in the San Simeon area islithologically similar to the Knoxville For-mation (14) in the Santa Maria area andthe Espada Formation of Dibbl«e (/7) far-ther south. In both the Point Sal and SanSimeon areas thc Jurassic shale containsbeds of conglomerate consisting of wcll-rounded, smooth, small. black chert peb-bles.

Stratigraphically above the Jurassicophiolitc-chert-shale sequ«ncc in both theSan Simeon and Point Sal areas is theLospe Formation (Fi». 2), a nonmarinerock unit consisting chielly of reddish con-glomerat«and coarse-grained sandstoneand tuIT overlain by grc«nish sandstoneand tulT (l4). In the Point Sal area theLospc Formation (/4. I5) of Oligoccnc agcoverlaps Jurassic shale and r«sts on thcophiolitc complex. In thc San Simeon areasimilar stratigraphic relationships arecomplicat«d by faulting (Fig. 2). Thcgreenish saridstone is not well developednear San Simeon. In both the Point Saland San Sitn«on areas thc «onglomerate isunsorted «nd poorly stratified. Clastsrange in size from a fcw inches to severalfeet in diatnctcr and consist of rocks fromthe ophiolitc «ompl«x and l«sscr amountsofJurassic chert and shale. Novvhcrc in the

H-2

Lospc I'ormation west of thc San Sin<«on

fault (Fig. 2) arc th«rc clasts ol'da«itcfclsitc from thc 22-million- to 26-millio<I-year-old Morro Rock-Islay flillcomplex(9, 13. 18), the dacitc ol'Ro«ky Butte(T1 inFig. I), or thc Camhria I'clsitc (9. le')). Da-citc and f«!sit«clasts are not pr«sent in thcLosp«Formation in thc I'oint Sal r«gion.flowcvcr, clasts of these rocks ar«pr«sentin the Lospe and Oligocene and lowerMiocene rocks only a fcw kilometers east

of San Simeon (9) and near Cambria.Thus, the inference is made that Lospc

~ strata west of thc S:m Simeon fault zonewerc not in the Cambria area at thc ti<ne oftheir deposition. Clasts ol'dacitc and Cam-bria Fclsite arc present only in Pleistoceneand younger deposits ivest of the San Sim-eon fault (4).

There are volcanic ash or tuff depositswithin thc Lospe Formation at both thcPoint Sal and San Siineon localities. AtPoint Sal the tulT occurs near the base ofthc conglomerate and near the middle ofthc Lospe Formation (14); north ol'anSimeon it occurs above conglomcratc.South of Point Sal, near Lions Head. alandslide occurs within the Lospc Forma-tion bcloiv a prominent white tutT b<.d (14).South of Breaker Point (Fig. 2) a largeOligocene hndslidc or alluvial fan also liesimmediately beloiv tuff and other volcanicrocks ivithin the Lospc 'Formation. flereclasts in the Lospc landslide are more vari-able in size and lithology than those in thcLospe landslide south ol'oint Sal: how-cvcr, at both localities the clasts arc pre-dominantly scrpcntinite, cabbro. diorite,and basaltic rocks. Thc occurrence of dis-tinctive landslides or landslide. like depos-its immediately below a tull'ed in thesame form'ation at two widely separatedlocalities on opposite sides of thc San Sim-eon-Hoscri fault system strongly arguesfor their preslip contiguity.

In addition to thc r«markabl«sim-ihritics between rock types, structuralstyles. and stratigraphic relationships ofthc dio rite and dike and sill complex withinthc ophiolitc and to thc presence of thcLospc Formation near Point Sal and SanSimeon, ther« i» an extraordinary resem-blance b«tiveen th« lithologics of thcmiddle or upper part of thc MontereyShale at these tivo areas. In both r« ionsand east and west of the San Simeon I'iiultthere is thin-h«ddcd cherty sliatc -a char-acteristic of thc iblontcfcy Slialc. I lowcvcr,west of thc San Simeon fault. approxi-mately km northivcst ot'an Sim«onP( int (I'ig. 2). 0.3- to I-m-<hi 'k I I.

ol'l:Ick«h«rt intcrh«ild«d ivith diatonia«coUssiltsto<ic <Ifc <<Iso I)resent. SI)U<h of I'$)intSal, n«ar I.ions llcail, id«ntical lithologicsoccur (14). I II)wcvcf. In tl<$.'sever;II hi<n

Fig. 3. Pfe.Quaternary com-posite stratigraphic sections ofrocks in the Point Sal-Lionsllead area, Santa BarbaraCounty (14. 15). and the SanSimeon Point-Ragged Pointa<ca. San Lui» Obispo County(4).

Point St)l Lion d

V C

oo~t<og~uo o os

Jsh

~ ~a~c»t C0dot aid I O

ducat Ohd Oosaeo I

Oiieoeho tel'NII

< lottet<Coetotd roeooteoh<

<<4llleeti rteeeoiah

deoOOSt

roche 5 $ < <O eOIOO

Loiot 4 hot oh

feohr IIIOO toilI

Jttoiiet Ilott

JotaSIK ihtel

Othettdt

Son Simeon PointRot)«et< Point

Tm+

'ho

ehJIVI de n~ J,o o.eie.,s' LQ o0$C),lc J<< 6 )C J<'Ce

Jsti

~++ Jere C2

dat ohd I u

rd<oeitt ahd ulttaehaha eOCII

If thc conclusion is correct. then th«rcare at least three signilicant corollaries.

I) Thc rate ol'motion b«tween the Pa«if-ic and North American plates. between 4.5and IO million years ago. averaged 4.5 cm/year accordinc to Ativater and %(ulnar(20). Therefore, 450 km of displac«mentwould have taken place within the last IO

million y«ars. This cal«ulated amount ex-ceeds right slip m«asurcd along thc SanAndreas fault by 150 km (21) during thelast IO to l2 million years. Sonic of th«rel-ative motion. 80 'km in 5 million to 13 mil-lion years, may have b«cn taken up or;ib-sorbcd in the Salinia block or-as suc-gcsted here —olTshore along thc San Sim-eon-Hosgri fault system.

2) The Santa Maria basin contains sev-

eral producing oil fields (/9). A thicknessof 300 m to 4 km of Cenozoic sedimentaryrocks is present offshore I'rom the SanSimeon area (1-3) and would bc part of theSanta Ih1aria basin that has been displ Icednorthward along the San Sim«on-Ilosgrifault system. Instead of simple w«stwardprojection ol'that part of the Santa Mariabasin, ivhich is currently produ«inc «om-mcrcial quantities ol'hydrocarbons. Un 80-km northwest projection might bc morcvalid.

3) Thc late Quaternary San Sim«on-Hosgri fault system could bc a pot«niialhiiz.ird to any «ngin«cr«d stru«tur« lo«:i<cdalong thc coast I'rom San Simt.'l)n soUtli tt)the vi«inityof Purisima Point (I'ig. I).

C. A. H*t.<. JR.Drpartrr<cr<t ofCieoir)gy.University ofCalijirrnirr.I.os rlngel<s t)N)24

ttcfcitncch and.'hutch

t. Earth Ssicnic A$ioci:Itch <Palo A<to. <'Ii<i<'.h -(ic-olugy of Ihc $ In<harn ( o,iii it ul<'c\ Iiui< thc <lii-<itinlltg ii<iiililteinil'Ilini'n<.'Iinl.lrrln Iii ( .IIII~ i<Ill.l,III<<I $ ficcta I rile <clice Iii Inc I'I'it<it}'iIn < Iic 'I IS IIII<I

of<he San t,uth Riinfc anil tii<cto tia$ .- re<hit< IorPaci<i«(eah anti I'<I~<tie('omp.in$ iiiciIahli.h ihi~

<cnuai Sir hciintis acnini <ha< iouhi a<fr« t)iahl.i(.al$ )'till fdili'<intr t oucr t'I.ill<<

I'IN I.Z. tt (i. <tuiLuih anil J. It. <iri<<iihq e<ett. C<iioi. l'rr.

(Irol. htrett. <S. 3< $ t te)11)

dred square kilometers that have been

mapped cast of the San Simeon fault andnorthwest ol'anta Mafia (9, 13) thickblack chert beds are not present.

A small outcrop probably of Plioceneagc has been mapped near San Simeon(Fig. 2) within the San Simeon fault zone.Thc outcrop contains marine fossil»: Den-drastcr spic bryozoa. Den<alias< spic Solensp.. and Nuculana 1Saccella) tapi<ria (Dull.f897). The fossils do not date the rocksmore precisely than early Pliocene toHolocene. The litholocy. hoivever. is sim-ilar to that of the Graciosa Coarsc-Grained Member of the Cureaga Sand-stone in thc Santa lvlaria area (14).

On the whole, strong stratigraphic andlithologic similarities exist between twopackages of five or six lithologic units ex-posed in the San Simeon and Point Salareas. Thc diameters of thcsc relativelyunique lithologic packagt.s arc estimatedat not morc than 20 km each (4, 9. 13-15,19). Rock sequences within a radius of 20to IOO km to the east of San Simeon areunlike those west ol'the San Simeon I'cult.

Comparison of the stratigraphic andlithologic histories of the areas near PointSal and San Sim«on (Fig. I), ar«as that licon opposite sides of the San Simeon-Hos-gri fault system, indicates stronc cvidcnccfor right slip of 80 or morc kilomctcrsalong thc fault system since thc late Mio-ccnc or cafly Plio««f<c. It is iissunlcd thats«paration is equal to or nearly «qual tothc horizontal slip compon«nt. Th» un-«ertainti«s of d«termining th«niinimumhorizontal slip compon«nt ar«equal to theunccrtainti«s. in onc dir««tion. ol'h«maxinium size ol'hc ar«a of thc strati-graphic packag«s. Thus. tli« liorizontal slipco<nponcnt is «ailculatcd to hc 80 k<n ormorc (tliat is. Uior« than IOO kin h«tween'I'oint Sal and San Sin<«on I'oint, minusthc cstimat«d maxiiuuin 20-LIII dia<n«t«rof thc area ol'h«str;itigraphi«p;Ickiigcs atS:in Siin«on;ind I',oint Sal).

H-3

67

IO

l2.

13

E. A. Silver. Sa~uin Grrrl. Srrr. Short Crnrrsr(l974) p.6 IC. A. Ii;rll Jr.. Geologic map of thc IricdtasElan«as-San Simeon region. Califutma. in ptcpr ~

ration.II. II. Vceb and J. W. Valentine. Grul, Sur'. rlnt.Bull, 78. 547 ( l9/rg).CaN/. Drp. It'atrr Krruur. Bull. Iid 2 (1964).E. S. Iloldcn. Srrrithson. Jlisr. Cullrrt. /087(I 897).P. Squibb. personal communication. hlr. Squibh ispata ps+ident uf thc San Luis Obispo County i(is.totica(Society.C. A. I lail Jr.. Grul. Srrc. vlnr. Bull. 7)L 559 ( l967):CoNf. Div.,tllnrs Grrrl.,tfup Shrrt (l973); U..S;Grol. Surv. 3/irr. FirldSturl..t /up.tl F.! I I ( I')73):US. Urrrl. Surv..tffrra Firld Strrd. Jlap t/F.!Ou(1974): D. L. Tutncr. Grrrl. Sr>c; Anr. Sprr. Pup.l24 (l970). p. 9I: D. L. Turner. R. C. Sutdam. C.A. Ilail.Grol. Sur. Am. rtbrtr. Curdillrrun Srrt. 2.I!5 (1970).II.C. tVagner. US. Grol. Surv. Oprn FilrRrp. 74-2!2 (1974).C. W. Jennings. Col% Div. 3/inrs Grul. Prrlirn.Rrp. IJ ( I973).W. Gawthtop. U.S. Graf. Surv. Oprn FilrKrp. 7$-IJs (I975IC. A. Ilail Jr.. "GcrrIoki«map of thc Cayucos-San Luiv Obispo region, 'Z. Grol. Surv.. rtfisr.FirtdS/ud..tlap. in press.

l4. tV, P. Nrrrrrdt(ng and ~ Itwmlctte. U 9. Grul.Surv. I'mf. Pup. 222 (~

IS. C. *. Ilupvmr. C. J. I:r o, L'. A. I'es«rgno. Jr.. J.M. Matttnwn. -I'tcliminary rc/Nrrt and gerrirreic

uide to thc Jur;rvsic ophiolitc near Point .'(al.'outhctn California «uast." Grul. Sar.:Iw. Car-

dillrrun Srrt. Guldrb. Firld 7rip Plu. ! (MarchI975).

l6. B, hl. Page. Grul. Sar. Anr. Bull. gl. 957 ( I972).(7. T. W. Dibhlcc Jr.. Calif. Div..tfinrs Bull. I!0

(I950).Ig, W. Cr. Ernst and C. A. Ilail Jr.. Grul. Sor. Anr.

Bull. 8<. 523 (1974).l9, Pacrfic Sectipn. American Asso«iation of Petro-

leum Gcologivts, Currrlatinn Sc anion across Santa.')/aria Burin I: ( l959k

20. T. Atrratcr and P. hlolnar. Stanford Univ. Pub/.IJ ( l973). p. I36.

2I. O. F. Ilulfman. Geol. So». rtnr. Bull. 83. 29(3( I972).

22. Public»ation approved by the director. U.S. Geolog-ical Survey. I thank W. G. Iitnst. G. Octtcl. E.Pampeyan. and II. Wagner for therr crrnstru«tivecomments. J. Gucnther and V. Jones drafted thcfigures. Research supported bv thc U.S. Gcologi ~

cal Survey. the (qu«lear RcguLnury Commission.and th» University of California Rcscar«h Com-mittee,

29 August l975: rcviscd l4 October l975

Copyriyht831/J78 bp the Ame)scan Association for the Advancement of Science

H-4

J. iiL

In press, to be ublished in "San Gregorio-Hosgri Fault Z , California," edited byE.A,. Silver o W. R. Hewmark, Calif. Div. ofMines cx Geology, Soecial Ressort 137.

ORXGIN AND DEVELOPMENT OF THE LO fPOC-SANTA lARIA PULL-APART

BASXN AND ITS RELATION TO TElE SAN SIMEON-HOSGRX STRIKE-SLIPFAULT, WESTERN CALXFORNXA

.Clarence A. Elall, Jr.Department of Earth and Space Sciences

University of California~ Los Angeles, California 90024

ABSTRACT

C ~

A model is proposed to account for the distribution of Cretaceous and Eocene .

sedimentary rocks, and distinctive Tertiary igneous, sedimentary, and volcani

clastic rocks'that lie within the Western Transverse Ranges and the Santa Maria-

Lompoc region, Santa Barbara County, California. Comparisons of lithologies and

stratigraphic sections tend to support the hypothesis that the Tertiary Santd

Maria-Lompoc basin is a pull-apart structure that began to form about 14 m.y.

ago. Following deposition of the late Tertiary sediments, the western part of

the basin was displaced, since the Pliocene, nearly 80 to 95 km to the northwest

along the San Simeon-Hosgri fault'one..

INTRODUCTION

A speculative model is proposed to account for the distribution of Tertiary

igneous, sedimentary, and volcaniclastic rocks that lie within the Santa Maria-

Lompoc region, Santa Barbara County, California.

Geologic mapping, analyses of core holes .and well data (Hall, 1977), and

preliminary field investigations southeast of Santa Maria, California suggest

the presence of the Santa Maria River fault (Fig. 1) and that the Santa Maria-

River-Foxen Canyon-Little Pine fault zone. (Fig. 1) may extend more than 100 km

to the southeast. Work on thi fault zone has brought to light some provoca-

tive geologic relationships which provide support for several structural models

for the development of Tertiary marine basins along the coast of California and

relatively recent movement on a major fault system in the region. In addition,

this work suggest's the presence of the inferred Lompoc-Solvang fault, which in

large measure appears to represent the northwestern structural margin of the

Transverse Ranges.

STRATIGRAPHY

Immediately northeast of the'anta Maria River fault (Hall, 1977; and

Fig. 1), i.e., within 3 'to 4 km of the fault, the following Mesozoic and Tertiary

rock units are present: (1) Franciscan melange (thickness unknown), (2) Unnamed

Cretaceous rocks (more than 457. m), (3) Sespe-Lospe formations (152 m),

(4) Vaqueros-Rincon formations (304 m),'5) Obispo Formation (335-.609 m),

(6) Point Sal or Lower Monterey Formation (304 m), and (7) Monterey Formation

(1066 m) (Table 1). The Sespe-Lospe formations are not known to be present

within 3 to 4 im southwest of the Santa Maria River fault. Southwest of the

Santa Maria R'ver fault, i.e., within a distance of 9.7 km of the fault, or in

the case of the Sespe-Lospe, more than 4 km from the fault, the following rock

units are present: (1) Franciscan melange (thickness unknown), (2) Sespe-Lospe

formations (609 m), (3) Point Sal Formation (228 m), (4) Monterey Formation

(629 m), (5) Sisquoc Formation (498 m), (6) Foxen Mudstone (88 m),

.(7) Careaga Sandstone (43 m) (Woodring and Bramlette, 1950; and Fig. 2).

Although the stratigraphy northeast and southwest of the Santa Maria River

fault is markedly different, i.e., Cretaceous rocks, Vaqueros Sandstone, and

iHncon Shale, and in part Sespe-Lospe are absent in the Santa Maria Valley area,

the most significant difference is the absence of between 335 m and 610 m of

volcanic rocks, including volcanic ash (Obispo Formation) within a distance of

35 to 40 km southwest of the fault, but the presence of the Tranquillon

volcaniclastic rocks, of the same age as the Obispo Foxmation, on the southwest

margin of the basin more than 35 km to the south (Fig. 1).

„TERTIARY BASIN HISTORY

At least three models can be proposed to account for the absence of rock

units with distinctive lithologies, namely, the Vaqueros, Rincon, and Obispoil

formations southwest of the Santa Maria River fault: (1) strike-slip movement of

tens of kilometers along the fault bringing into juxtaposition markedly dif-ferent stratigraphic sections; (2) the area between the Santa Ynez Mountains and

the Santa Maria River was a topographic high during the time when the Vaqueros

and Rincon ormations were being deposited elsewhere in the region, and the

Obispo-Tranquillon volcan'c rocks have been eroded from this region; or (3) the

development oz a'ull-apart basin (the" formation of pull-apart basins is dis-

cussed by Crowell, 1974) zollowing the deposition of the Vaqueros, Rincon, and

Obispo-Tranquillon zormat'ons. The first hypothesis, namely large post-Monterey

Formation or Obispo-Tranquillon volcanic rock strike-slip along the Santa Maria

River fault, is difzicult to test. If right-slip along the fault did occur,'t

the Obispo volcanic rocks formerly near the intersection of the Santa Maria

River and Santa Maria Mesa faults (Fig. 1) would have been moved northwestward

and 'now would be buried beneath the Pismo sand dunes ox lie below San Luis Bay

in the Pacific Ocean'(Jennings, 1959; Hall and Corbato, 1967; Hall; 1973)-

The second hypothesis, that is, prior to the deposition of the Monterey

shales the area between the Santa Ynez Mountains and the Santa Maria River fault

was a topographic high, or the Vaqueros, Rincon and Obispo formations were

deposited and subsequently eroded away, can ezplain the distribution of the

Tertiary rocks. However, the absence of Cretaceous rocks in this area, but

their presence bounding t'e area (Fig. 1) and the presence .of Eocene rocks north

~ ~

4

i

and south of the Little Pine fault,'near the Lorna Alta fault '(Fig. 1), but their

absence in the subsurface in the vicinity of Santa Ynez, approximately 15 km to

the west of the Lorna Alta fault, and elsewhere in the basin between the Santa

Haria River-Foxen Canyon fault (Fig. 1), is difficult to explain by this hypo-

thesis, unless one assumes that the Cretaceous or Eocene rocks were also erodedI

completely off of a Franciscan topographic high. Also, subsurface data do not „,

provide evidence of uneroded remnants of these units. Furthermore, if the

wedge-shaped Santa Haria basin was a high during or following, for example,

the time of deposition of the Vaqueros and. Rincon in or surrounding the region

and the deposition of the Obispo volcanic ash in a marine environment within the

basin, it would require an unusual history for the basin. The events would have

been: (a) the deposition of the non-marine Sespe-Lospe formations, (b) the

deposition of the shallow-water marine Vaqueros Sandstone followed by the

deep-water deposited ~~ con Shale either surrounding the basin or within the

basin, (c) the deposition of the Obispo tuff within a marine, basin, (3) the

'eep-water basin would have been uplifted,'ith the Vaqueros, Rincon, and Obispo

eroded away, and (3) the" the area would have been down-dropped almost simul-

taneously w'th the erosion of the Obispo Formation so that the deep-water Point

Sal or Lower Monterey and Monterey Formations could be deposited in a deepening

basin. Note that the base of the Monterey Formation is between 10,000 and 15,000

feet (3048 to 4572 m),below sea level (Fig. 1). Thus a wedge-shaped high would'I

have to persist from Oligocene to Miocene while the area surrounding'he high

would be subsiding, and then the high-standing land mass would have to subside

rapidly in theHiocene and Pliocene to allow deep-water Point Sal, Monterey and

Pliocene sediments to cover the supposed high-standing land mass.

Comparisons of lithologies and stratigraphic sections (Table 1) tend to

support the third model for the development of a.Santa Maria-Lompoc pull-apart

basin, although detailed stratigraphic and lithologic studies are yet to be

made. In the western Santa Ynez Mountains the stratigraphic section is unlike

that north of Santa Ynez Valley (Lompoc, Buellton, Santa Ynez,, Fig. 1),.but it .

agrees relatively closely with the stratigraphic section north of the Santa

Maria River-Little Pine fault system nearly 45 km to. the north (near Santa

Maria, Fig. 1, Table 1). The stratigraphic section in the western Santa Ynez

Mountains (east of Point Arguello, Fig. 1) includes: (1) Franciscan melange

and Honda Formation (457 m), (2) Cretaceous rocks (2743 m), (3) Oligocene and

Eocene rocks (1981 m), (4) Sespe-Lospe formation (91 m), (5) Vaqueros-Rincon

units (213 m), (6) Tranquillon Volcanics (365 m), and (7) Monterey Formation

(914 m). Tne Tranquillon Volcanics are the same age as the Obispo Formation

(Tranquillon Volcanics: 17 + 1.2 (basalt), 16.8 + .5 (tuff), 16.1 i ..6 (tuff)m.y.; Obispo Formation: 15.3 + .9, 16.3 + .5, 15.4 + .5, 15.3 + .5, 16.5 + .8

m.y.; Turner, 1970). This sequence of rocks does not correspond exactly with

tha on the north s"de of the basin, namely north of the Santa Maria River fault,and a reconstruction of the Tertiary geologic history of the region prior to

pulling apart of the basin is required to understand why exact correlations

cannot be made.

A generalized possible Tertiary history of the development of the Santa

Maria-Lompoc basin could be as follows. Figure 2a shows a generalized paleo-

geologic map after the deposition of the Gaviota Formation of Oligocene age and

older rock units (Cretaceous, K; Eocene, E). Before deposition of the non-

marine Sespe Formation there could have been strike-slip along the inferred

fault, as shown in Figure 2b (diamonds). Later, oblique rifting along this

fault (post Obispo, post Fig. 2d time) would account for the development of the .

Santa Maria-Lompoc basin. The inferred fault (diamonds) is called the Lompoc-

Solvang fault (Fig. 1). Its inferred presence is supported by the fact that

north of its approximate location the stratigraphy (known from exploratory oilwells) is markedly different from that south of the inferred fault. Figure 2c

depicts a generali.zed paleogeologic map before the deposition of the Monterey

Formation. Sespe-Alegria formations (in part Lospe Formation), Vaqueros Sand-

stone, Rincon Shale, and Obispo-Tranquillon volcanic rocks unconformably over-

lie the Franciscan rocks (F), Cretaceous rocks (K), Eocene rocks (E), and

Oligocene (Gaviota Formation) rocks (0).(F, K, E, and 0 shown as dotted and

buried contacts)- The fault (diamond) was either buried or was continuously or

sporadically active during the deposition of the Tertiary rocks shown in Figure 2c.'\

Subsequently, a series of pull-apart basins may have developed along the present

coastal part of central California, one such basin being the Santa Maria-Lompoc5hzbasin. The Santa Maria-Lompoc basin was probably later transected by„San

zoneSimeon-Hosgri faultv(Eall, 1975a). After deposi.tion of the Obispo-Tranquillon

volcanic rocks, the formation of the Santa Maria-Lompoc basin (Fig. 2d) began .

with the development along the right-slip transform Lompoc-Solvang-Santa Maria

River-Foxen Canyon-Little Pine fault system, or there was renewed movement

along this already extant fault system, 'possibly during the Luisian A e (14 m.y.b.p.).

The margins of the basin were formed by the.Lompoc-Solvang fault (diamonds) (or

pull-apart shoulder) and the Santa Maria River-Little Pine fault (triangles) (or .

pull-apart shoulder). Right-slip along the fault probably accompanied dip-slipand the late Miocene and Pliocene seas flooded the deepening basin; note that

near Los Alamos the base of the Monterey Formation is nearly 4,572 m (15,000 feet)

below sea level (Fig. 1), that the maximum subsurface thickness of the Monterey

Formation is probably more than 1,524 m (5,000 feet) thi.ck, and the maximum out-

crop thickness at the margins of the basin is approximately 655 m.(2150 feet).

It is suggested that the Santa Maria River and Lompoc-'Solvang faults are part of

the same transform-right lateral fault system and before the late Miocene pull-

apart, to produce*the Santa Haria-Lompoc basin, were probably a single fault or

fault zone. The formation of the late Tertiary pull-apart basin, with motiont

vectors of extension parallel to the strike-slip faults, began following the

deposition of the Obispo (Tranquillon) Formation, probably during. the middle

Miocene (14 m.y.b.p.). Halls along the fault margins may have begun to sag and

pull apart as early 'as the early Oligocene, or even earlier if there was more thanI

one episode of rifting. The Franciscan rocks are weak, easily folded, faulted,

and stretched or became even more tectonically brecciated. What occurred to the

deeper crustal layers is unknown, but there was not massive extrusion. During

t¹ opening of the basin only minor volcanic flows or intrusions (e.g., those.

near Point Sal) occurred contemporaneously, with the pull-apart and'the stretch-

ing of the F"anc scan. Rotational movement (Fig. 2e) or bending accompanied

formation of the. pull-apart basin. This movement resulted in a change of trend

of the Lompoc-Solvang fault (Fig. 2d) from northwest to east-west (Fig. 2e).

The rotation or bending ~~ould account for the distribution fo the Cretaceous (K),

Eocene (E), and Oligoce"e (0) rocks south of the inferred Lompoc-Solvang fault

and may have played a role in or during the general development of the Transverse

Ranges. Th amount of counter-clockwise rotation is reduced if the 'Lompoc-Solvang

fault initially had a more westerly trend. The'maximum pull-apart is between 40

and. 50 kilometers. Because of probable strike-slip along the Lompoc-Solvang-

Santa Maria River-Little Pine faults, the Cretaceous and Eocene rocks, Gaviota

Formation, Vaqueros Sandstone, Rincon Shale, and Obispo-Tranquillon volcanic'I

rocks near Point Arguello probably were in closer juxtaposition,.initially with

rocks of the same lithology and ages at the latitude of Camuesa fault (Fig. 1)

or near Zaca Lake. (Jennings, 1959) .than with rocks near the Santa Maria River

fault. That is, the rocks"south of Lompoc and Solvang, in the Transverse Ranges,

have moved along a right-slip transform Lompoc-Solvang-Santa'Haria River-Little

8

Pine fault, the basin opened along this fault, rotation or bending occurred, and the

Lompoc-Solvang fault and rocks south of the fault were brought into their present

position. Left-slip occur'red at a later time along a Santa Ynez-Pezzoni fault

system (partially shown in Fig. 1).

Following the deposition of the 'late Tertiary sediments (Sisquoc,'oxen,

Caxeaga formations), within the deepened basin, a part of it was moved morezone

than 80 km to the north along the San Simeon-Hosgri fault (Hall, 1975a). It is

unlikely that. the slip is less than 80 km. Evidence for this unlikelihood is

provided by the fact that the package of rocks, in the Santa Maria region (i.fe.,

Jurassic ophiolite., chert, and shale, Lospe Formation, Monterey Formation, andzone

'liocene rocks), which were moved north along the San Simeon-Hosgri fault has

a distribution limited to the Santa Maria basin. At its widest the basin is

about 50 kilometers (30 miles). However, it will be noted that the known dis-

tribution of the Jurassic ophiolite, chert, shale, Lospe Formation and associated

younger rocks tha- crop out near Point Sal are known from the subsurface in an

area of less than 19 km (12 miles). The distance between Point Sal and the San

Simeon area (Fig. 3) is mo e than 100 km (62 miles), the diameter of the unique

package of rocks in the Santa Maria area is less than 20 km, thus the offset

would be at least 80 km, and more likely 95 km. The releasing half bend,

depicted at the southeast end of the pull-apart basin in Figure 2d, would have

had a mirror image at the northwest end, but this has been truncated by the'an

Simeon-Hosgri fault and is now 100 km to the north at San Simeon (Fig. 3). The

Pliocene Careaga Sandstone at San Simeon suggests that the 80 to 95 km of

,right-slip along the San Simeon-Hosgri fault occurred during the last 5 m.y.

The earliest'strike-slip movement along the San Simeon-Hosgri fault would

probably be 9 to 13 m.y. 'learly all movement took place along the faultIf

following the formation of the pull-apart structure.

~ p ~ ~

~ ~Some investigators have suggested that the offshore exploratory well,

Standard-Humble ffl (Fig. 3), contains a section of rocks that is most like

that onshore at or near the same latitude (Santa 'Feria Valley). The off-

shore well encountered the following section: top of the Sisquoc at 3402

ft (thickness 635 m or 2082 ft); top Monterey at 5484 ft (thickness 358 m

or 1176 ft); top of volcanicash (probably Obispo-Tranquillon volcanics) at

6660 ft (thickness 122 m, or 400 ft); top of "volcanic rocks" (probably

Lospe, personal communication David Howell, 1977) at 7060 ft (bottom of well

at 7797 ft). Onshore, at or near the same latitude, well data (Woodring

and Bramlette, 1950, cross section A-A') provide information to show that

the Monterey Fo~~~~tion lies either on the Lospe or directly on Franciscan

rocks; whereas the well probably contains volcanic ash,'of the Obispo or

Tranquillon volcanic rocks. The section in the offshore well might best be

correlated on land with rocks either south of the Lompoc-Solvang fault (i.e.,near Point Arguel"o; see Dibblee, 1950, geologic map) or possibly witn the

Standard Oil "Sh~-.-ers":"-1 south of Purisima Point(section 4 T.7S., R.35W.),

/herc.more than 32 km (20 miles) south of the„well on the opposite-side of the

the S~gv~roSan Simeon-Hosgri fault zone. The partial log of well shown in

Figure 1 is probably incorrect and the units encountered were probably'I

Monterey overlying Obispo-Tranquillon volcanics, which in turn overlies

the Lospe Formation. The well was drilled in 1928 and 1929. Thus, the

offshore well could easily support but does not detract from the model of

a pull-apart basin and offset along the San Simeon-Hosgri fault measured in

tens of kilometers.

Continuous or renewed late Tertiary or Quaternary movement must

have occurred along the Santa >faria River fault. Evidence for this suggestion

is provided by the geology in the Twitchell Dam quadrangle 01all, 1977)

and the geomorphology and late Tertiary and Quaternary geology along*the

Foxen Canyon fault (Fig. 1). In the Twi.tchell Dam quadrangle the Rest

Huasna fault faults Quaternary deposits and is in turn truncated by, or is

the same age as, the Santa Maria River fault.

OTHER NEARBY REGIONAL BASINS

The Morro Bay basin to the north of Santa Maria basin (50 km north of

Santa Haria) shows similar relationships to the development of the Santa

Maria basin. Although the correlation of rocks at the margins of the Horro

Bay Tertiary oasin is not as clear as those at the, margins of the Santa

Maria-Lompoc basin, the Horro Bay basin might also represent a pull-apart

structure. The basin may have begun to open during the early Oligocene and

the dacite-felsite rocks of that age, forming Horro Rock and 12 to 13

other major int~sive masses in the'area (including the Cambria Felsite),

may reflect a period of volcanism and intrusion at depth during basin

opening. Such a. interpretation would have to account for the fact that

the rifted intrusive rocks were dacitic and not basaltic rocks. Equally

as speculative is the suggestion that the Horro Rock-Islay Hill complex

(Ernst and Hall, 1974) was rotated 10 to 15 degrees to the west after

emplacement, and that the Cambria Felsite in Cambria and at RockyButte'Hall,

1973, 1974, 1975b; Hall and Corbato, 1967; Hall and Prior, 1975)

' '

~ . ~were aligned with the lforro Rock-Islay Hill complex at the time of emplacement

during the Oligocene. An alternative explanation for the Horro Bay basin isk

that it is an uplifted, tipped fault wedge basin (see Crowell, 1974) bounded

by the Pismo and Huasna inclined subsidence basins. Such a suggestion does not

preclude pre-mid or late Miocene counterclockwise rotation. If the'Horro Bay

basin is an uplifted tipped basin, it must have subsided during late liiocene

or Pliocene time because remnants of rocks of these ages are present within

the regions bounded by the Edna-Los Osos Valley and West Huasna fault systems.

These faults form the margins of the hlorro Bay tipped fault wedge basin.

Sb~MARY

Based on the geology, stratigraphy, distribution of sedimentary and vol-

canic rocks, and lithologic similarities of widely separated rock types, there

is evidence to support tne hypothe'sis that the Santa?4ria-Lompoc basin is a

pull-apart structure. The fault-bounded basin is wedge-shaped with the maximum

pull-apart being nearly 50 km. The basin may have undergone recurrent periods

of r'ing, perhaps during the deposition of the Rincon Shale, the most recent

of which took place approximately 14 m.y.'b.p- The present location and orienta-

tion of the Cretaceous to middle Miocene rocks in the Western Transverse Ranges

are due to right slip along the Lompoc-Solvang-Santa ?faria River-Little Pine

right lateral transform, subsequent counter-clocLmise rotation or bending of

the region, and late Tertiary and 'Quaternary left slip along the Santa Ynez fault.T

Other basins in the region, e.g. Pismo and Huasna, are possibly tipped sub-

sidence basins (Crowell, 1974) and the Morro Bay basin is a tipped fault wedge

basin (Crowell, 1974). All structural basins were probably formed between large

strike-slip faults during late middle or late Hiocene and were in part later

affected by movement along such faults as the San Simeon-Hosgri fault a„one

12

and Rinconda,Fault (Dibblee, 1976). There has apparently been at. least 80 orQoaa

95 km of right slip along the ~L~~i~>~-~~>~« ~~It„since the Pliocene (during

the last 5 m.y.) and following the formation of the Santa Maria-Lompoc pull-

apart basin.

ACKNOWLEDGi1ENTS

I wish to thank J. C. Crowell, W. G. Ernst, W. R. Dickinson, and Eli Silver

for their helpful comments and discussions of the concepts expressed in this

paper.

. ~REFERENCES

13

Crowell, J. C., 1974, Origin of late Cenozoi'c basins in southern

California, in Tectonics and Sedimentation, edited by W. R.

Dickinson: Soc. Econ. Paleontologists and Mineralogists

Spec. Paper no. 22, pp. 190-204.

Dibblee, T. W., Jr., 1950, Geology of southwestern SantaBarbara'ounty,

California: Calif. Div. Mines Bull. 150, pp. 1-84,

maps ~

Dibblee, T. W., Jr. 1976, The Rinconada and related faults in the

Southern California Coast Ranges, California, and their tec-

tonic significance: U. S. Geological Survey Professional

Paper 981, 55 p.

Ernst, W. G., and Hall, C. A., 1974, Geology and petrology of thek

Cambria Felsite, a new Oligocene formation, west-central Calif-

ornia Coas" Ranges: Geol. Soc. America Bull., v. 85, pp. 523-

532.

Hall, C. A., Jr., 1975a, San Simeon-Hosgri fault system coastal Cali-

fornia: Economic and environmental implications: Science, v.

190, pp. 1291-1294.

Hall, C. A., Jr. 1975b, Geologic tfap of the San Simeon-Piedras Blancas

region, San Luis Obispo County, California: U. S. Geological

Survey Misc. Field Studies Map MF 784, scale 1:24,000.

Hall, C. A., Jr., 1977, Geologic Map of the Tw»4~ii ><~ »" P~">~ ~k >~= ~"" "g„d TePuSqaef Puadringlc>>

Santa Barbara County, California: U. S. Geological Survey Misc.

Field Studies Map, scale of 1:24,000 (in press).

'I

References continued

Hall, C. A., Jr. and Corbato, C. E., 1967, Stratigraphy'nd structure

of Mesozoic and Cenozoic rocks, Nipomo Quadrangle, Southern Coast

Ranges, California: Geol. Soc. America Bull., v. 78, p. 559-582.

Hall, C. A., Jr. and Prior, S. W., 1975, Geologic Map of the Cayucos-

San Luis Obispo region, San Luis Obispo County, California: U. S.

Geological Survey Misc. Field Studies Map kfF 686, scale 1:24,000

Jennings, C. V., 1959, Geologic Map of California, Olaf P. Jenkins

Edition, Santa ~faria Sheet.I

Jennings, C. H. and Strand., R. G., 1969, Geologic Map of California,

Olaf P. Jenkins Edition, Los Angeles Sheet.

Turner, D. L., 1970, Potassium-argon dating of Pacific Coast Miocene

foraminiferal stages: Geol. Soc. America Spec. Paper 124, pp. 91-

129.

Voodring, H. P., and Bramlette, M. N., 1950, Geology and paleontology

of the Santa Maria district, California: U. S. Geological Survey

Prof. Paper 222, 142 pp., maps.

Western SantaA e of rock units Ynez Mountains

Santa Maria-Lom oc basin

Cuyama-Santa Maria-Sis uoc Rivers area

Pliocene

Pliocene

Miocene-Fliocene

Miocene

Miocene

Miocene

Oligocene-Miocene .

Oligocene

Oligocene

-Sisquoc Fm.

Monterey Pm.

L. Mont. I'm.

TranquillonVolcanics

Rincon Shale

Vaqueros Ss.

Sespe/AlegriaPormations

Careaga Sandstone

Poxen Hudstone

Sisquoc I'in.

Monterey I'm.

Pt. Sal Pm.

Sespe-LospeFormations

Monterey Fm.

Pt. Sal Pm.

Obispo Fm.

Rincon Shale

Vaqueros Ss.

Sespe Pm.

Oligocene

Eocene

Cretaceous .

JurassicCretaceous-Jurassicor Jurassic

Gaviota Pm.

Eocene rocks

Cretaceous rocks

Honda Fm.

Franciscan rocks'Knoxville" Fm.

Pranciscan rocksor ophiolite

Cretaceous rocks

Jurassic shale

Franciscan rocks

Table 1 Generalized pre-Pleistocene stratigraphic sections from themargins of the Lompoc Santa Maria basin, western Santa Ynez.Mountains (Dibblee, 1950), Santa Maria and Lompoc basins(Woodring and Bramlette, 1950), and the area north of theSanta Maria River (Hall, 1977), Santa Barbara County,California.

"~FIGURE CAPTIONS

16L

CI

I I'

FIGURE l. Generalized paleogeologic map (pre-Monterey Formation and generalized

structure contour map. (base of ifonterey Formation), San Luis Obispo

and Santa Barbara Counties, California. Generalized distribution of

selected stratigraphic units is from Jennings (1959), Hall (1977),.re-

.donnaissance . geologic mapping in the Sisquoc and Lompoc areas, and

from core hole data supplied by the California Division of Oil and Gas,from well logs

Santa Haria District Office. Incomplete well data are shown: i~lon-

terey Formation, Tm; Point Sal Formation, Tps; "Temblor" Formation,,

Tt; Rincon Shale, Tr; Vaqueros Sandstone, Tv; Lospe Formation, Tl;

Franciscan rocks, KJf; Jurassic shale, Jsh; Jurassic ophiolite, Jo.

A. Sylvester (Univ. Calif., Santa Barbara) reports (personal communi-

cation, 1977) the presence of a fault in the vicinity of Santa Ynez

4

. and Solvang with a northwest trend. I believe that this fault is a

continuation oz the Pezzoni fault and passes near Los Alamos; -the

exact location, however, is unknown;'I

FIGURES 2a-2e. Hypo the tical paleogeologic maps.

U

Figure 2a. —Hypothetical paleogeologic map following or during the deposition

of the Gaviota Formation of Oligocene age. Coastal part of California.

r

Figure 2b. —Hypothetical paleogeologic map, following strike-slip along the

Lompoc-Solvang-Little Pine fault and before the deposition of the7

Sespe-Lospe formations. Coastal part of California in the vicinity

of what is now northwestern Santa Barbara County. The initialtrend and amount of strike-slip is not known.

Figure 2c. —Hypothetical paleogeologic map following deposition of the

Obispo-Tranquillon volcanic rocks. Following deposition of the

Ga'viota Formation and strike-slip on the Lompoc-Solvang fault,

the Sespe (and the marine equivalent Alegria) (coarse swirled

dots), Vaqueros (fine random dots), Rincon and Obispo-Tranquillon

rocks (fine mixed dots) were successively (northeast-southwest

trend) and unconformably deposited upon the underlying Franciscan

(F) (vertically ruled), Cretaceous (K) (horizontally ruled),

Eocene (E) (no pattern), and some Oligocene (0) (diagonally

ruled) rocks.

Figure 2d. —Hypothetical paleogeologic map showing geology of northwestern

Santa Barbara County approximately 14 m.y.b.p. Basin pull-apart

began to develop along the Lompoc-Solvang-Little Pine fault con-

te-poraneously with the birth of the Santa Maria River-Foxen Canyon-

Little Pine fault zone. Vaqueros, Rincon, and volcanic rocks are

at the margins of the opening basin, but are removed, except for

remnants left on the stretched and tectonically mixed Franciscant

; rocks, from the center of the basin. Cretaceous, Eocene, and Oligo-

cene rocks along with the overlying Sespe, Vaqueros, Rincon and

Obispo-Tranquillon rocks are southwest of the Lompoc-Solvang-zone

Little Pine fault (diamonds); Franciscan and remnants of the Sespe

rocks lie between the two faults, and Cretaceous, Sespe, Vaqueros,

Rincon, and Obispo rocks lie northeast of the Santa hfaria River-

Foxen Canyon-Little Pine fault zone (triangles). Strike-slip

probably accompanied the development of the pull-apart basin.

~ ' ~ ~

18

Figure 2e. —Generalized pre-late Miocene 'paleogeologic map. The proposed

model suggests the counterclockwise rotation of the Lompoc-Solvang-

Little Pine fault, rotation that has occurred some time since the

late middle pliocene. The inferred Lompoc-Solvang fault in the

proposed model is the northern boundary of Transverse Ranges in

the western part of Santa Barbara County.

FIGURE 3.. Location of the San Simeon-Hosgri fault z'one, Santa Maria River,

Lompoc-Solvang, and other faults., Spots (Ti ~ Tertiary intrusive)

indicate sites of Oligocene hypabyssal volcanic rocks, including

the iforro Rock;Islay Hill volcanic rocks and similar rocks in the

north near Rocky Butte. Location of Standard, Oil Co. of California-

Humble Oil Co. "Oceano 81" is shown west of San Simeon-Hosgri

fault system.

PIIrisimoPoinl

RjntArguelio

GENERALIZED PALEOGEOLOGIC MAP 'tPItE MOilTEREY I'ORMATIONl ANDGENERAI.IZED STRUCTURE CONTOUR MAP (13ASE OF MONTEREY FORMATIONl

SAN LUIS OBISPO-SAN'I'A 13AR13ARA COUNTIES, CAI.IFOI~WIAOn/ EXPI ANATION

Oara~ Oll '-": I;Wa:I Haaaaa faallQGUAoALupE Cretaceous rocks

f="..] Vaqueros Sandstone- „Jt „Franciscan melange-I-'-.:MRincon Shoto . ophiolile complex4 X<~ P;) LB4/( lll

P GET TERAVIA4Jo 'I 3 Oooo a

II Eoo i»

'o

I."..'.-;:,'; .'espe-Lospe Formotion s Serpenlinile

Limit of Monterey

T ~ ~

EE

~ Santa Mario River fault

0C~Oy

0 — 5

0 5 t0

QORCUTT - .' 0 X~~ip

/io ~

Limit of LospeFormotion,p/~~ 4 / o

CASMALIA I- - X 'e, 'i iX ~~ ~ .:-:- —In«- Structure contour line'EE

0Cp ,.4 K= Lompoc-Solvang faults6~

Q LOS ALAMOS ~(„o

KJtIa *

Tm srn ( 4nl V~ 4 Exploratory oil well

o u//o~

BOE

+~™Haaaa Iaa ~ + L, ~~ ~OBUELLTOU OOOUTO Tl,'EE+ BBITBBE forll

E p

~

E x4 ro/jr

~E n E

~

T

ao4 f

$onto )n -~ ~<u//

-"-+4 Q~(OIIO -- ~ /GAVIOTA PASS foulg50

miles/ 15km.

'a

PoifltConeepifen Pacific Ocean

=CRI

TACEQUS'OCENE FR ANCISCAROCKS 1

'll

OLIGOCENElGAVIOTAl

EOCENE

OLIGOCENExfGAVIOTAl8/8/1 zr g

fllit

'rer

!ii

:rr

te

'-'"::OBISPO-'.."': " . ",ir-" lt. TR.4iQLILLO«,,

', i'..',.-,*",.«,,,;.'e',.";! "Y.;:-,.":,"::.;

't"~llj jt f

Cef

e ~ e

~, ' e ~

I

I

K.:;,".': 'OBISPO .: '.-'TRAhQUILLOtr—.

rt

fr[!tileSESl!~jm~

~ ~e

, jhT}

PF

rrt ~

e

ttree

eje

tetrlifj

ece ~

r'j

ttt

SSE Piji

rf

'::.', ..'.: ';, ."„:::e."!",,:;.'-',li, vAQUERQsgll

iGi c ':,".e:,t'.::~..:.„;![i

t ~$ - „l<!„.~

J!,RZ'.-CO'~

l,II

l

Cf. )t t t

OaIS ''>. i gll,lijff!e.ll!i~

'! l,l

ljf,'—

OBISPO-—,THANQUILL'Oi

—Rr~ro~",.'-',-" "',j!-;-'''SFRPEj i~"-

;...VAQUEROS

I-20

I~ ~

36o

35o

0

Cape Son Martin '.

~ ~~ ~ee ~ ~

~ ~ ~~ ~~ ~~ ~

~ ~

~ ~

OC te)

MorroBoy

(0~ e

Pt. Son Luis

~ eeI

:.(q~ C~ ~

~ p

Vp~

p0

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CD

e

e

e

Arroyo6 ronde

Sp0 IL

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Santo 4@~

Morio

PG

0 10 kilometers

Santo Morio-Lompoc Basin~ ~ ~

~ ~ ~~ ~ ~~ ~

Rogged Pt.~ e ~~ ~ ~~ ~ ~~ ~ l Pocky Tj(d

pt. Piedros BlancosSan Simeon

Son Simeon Pt. Poso RobicsDc

'.+ Cambrio

Oil OG

Pt. Buch

~ ~

~ ee

~ ~ ~ e ~~ p ~ ee~ ee ~ ~ ~

~ ee' ee~ W ~~ ~ ~ ~

~ ~ ~~ ~

Stondard-.Humble . + '-.Oceano Nl

'e 0

:. ~Pt. SallQ miles

Heod

~ ~

Purisimo Pt.

MapLocation

~ ~~ ~ ~ e ~ e~ ~ ~

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I

ATTAC11MENT J

~~

MARINE GEOLOGY AND TECTONIC HISTORY OF THE

CENTRAL CALXFORNIA CONTINENTAL MARGIN

Eli A. Silver 2

David S. McCulloch 3

Joseph R. Curray 4

Santa Cruz, CaliforniaMenlo Park, Cali forniaLa Jolla, California

ABSTRACT

The geology of the central California continental margin

shows a history of early Tertiary subduction of the Farallon platek

and followed by a Miocene and younger period of high angle

faulting and basin formation corresponding to transform movement

between the Pacific and North American plates. Seismic reflectionprofiles show irregular structural surfaces on the older sedi-mentary rocks, which are overlain-by mildly warped younger strata.

'argeshelf basins, including the . Santa Maria, Sur, Outer Santa

Cruz, Bodega, and Pt. Arena basins, are bounded by down-to-basin

faults. The structural style of most'f these basins is similar,although the Pt. Arena, Outer Santa Cruz, Santa Maria and Sur

basins probably rest on Franciscan basement and the Bodega lieson granitic basement.

Drilling data suggest. a nearly synchronous origin for these

basins in 'middle Miocene time (Hoskins and Griffiths, 1971) . Analysisof pi..esently available data for the history of finite plate movements

since the middle Cenozoic suggests a westward shift in the direction

of movement of the Pacific plate relative to the North American

plate in this region about 10 million years ago (m.y.a.). Such

a change in plate motion could have provided a sufficient

extensional component of movement to result in basin formation,

possibly along the older structural grain of the margin. Some

of the Quaternary faulting is high angle reverse in sense,

indicating a compressional component acting over approximately

the last million years. lt is possible that the instantaneous

movement between the Pacific and North American plates has been

changing continually during the past 30 m.y.

The distribution of granitic rocks of the Salinian block

on the continental margin constra'ins measurements of offset

along the San Andreas and San Gregorio faults. The San Andreas

system of faults shows at least 550 km and a maximum of 600 km

offset, based on the northern extent of granitic basement under-

lying Farallon ridge. The San Gregorio fault has an estimated

offset of 100 + 15 km, based on offset of the southern end of

Farallon ridge.

These observations support the idea of slivering within the

Salinian block (Johnson and Normark,.'1974). However, early

Tertiary paleogeographic reconstructions by Nilsen and Clarke

(1975) require some Salinian offset by early Paleocene, in

contrast to the model of Johnson and Nomark. We favor approxi-

mately 100 km of offset during latest Cretaceous to Paleocene time

and 450 to 500 km offset after 22 m.y.a. Granitic boulders dredged

from Santa Lucia Bank, far west of the Salinian block, raise the

question of either the presence of granitic fault slices west of

J-2

~ ~I ~ 1

the Salinian block or exten ive transport of these boulders

from Salinian source areas.

Manuscript Received Accepted

2. University of California, Santa Cruz, California 95064

3. U. S. Geological Survey, Menlo Park, CA 94025

4. - Scripps Xnstitution of Oceanography, La Jolla, CA 92093

We thank W. R. Normark and H. C. Wagner for careful reviews

and suggestions. D. G. Moore, R. von Huene and H. G. Green'e

generously allowed, use of unpublished reflection profiles, and the

National Ocean Survey generously allowed use of unpublished gravityand magnetic data. We are grateful to T; C. Worsley for paleonto-

logic analysis, to L. Silver, E. C. Beutner and L. Lee fox

petrologic examination of some of the rocks collected, and to

C. McHendrie and Robert Brune for a great deal of effortin providing computer output of much of the data. We are gratefulfor discussions with and ideas from,C. G. Chase, T. Atwater,

S. A. Graham, W. R. Dickinson, W. Gawthrop, C. H. Hall, D. Hamilton,

J. Crouch, E. C. Bcutner, J. C. Crowell, T. Nilsen, and to a greatJ'anypeople, too numerous to mention or to properly recall, who

contributed to thi+ work in very significant ways. Our lack ofcitation here is not through lack of gratitude or indebtedness.

We finally thank the captains, crews and scientific parties of many

expeditions to the rolling seas off central Califor'nia for theircooperation and support.

INTRODUCTION

The continental margin off Central California, between the

Mendocino and Murray fracture zones, has undergone a complex

tectonic development during Cenozoic time. Atwater (1970) has

interpreted the magnetic anomaly pattern in the northeast Pacificto imply subduction of the Farallon plate (McI(enzie and Morgan,

1969) beneath the margin in the early Tertiary. Approximately

30 m.y.a. subduction began to cease along Central Californiaand strike slip faulting subsequently began along the margin.

I

These tectonic processes probably played a major role in develop-

ing the structure of the margin. The present study describes

that structure and evaluates hypotheses for the Cenozoic tectonic,.evolution of the continental margin.

Geophysical study of the margin has included single channel

seismic reflection profiling, utilizing high and low energy sound

sources, on approximately nine expeditions of the Scripps Institu-tion of Oceanography'nd of the U. S. Geological Survey since 1964

(Fig. 1). Additional detailed studies are available for Monterey .

Bay (Greene, 1970), at Point Arena (unpublished Pacific Gas and

Electric Company report) and between Point Arguello and Point Sur

(McCulloch and others, 1977; Buchanan-Banks and others, 1978).

Gravity and magnetic data were obtained between San Francisco and

Point Arguello and magnetic data north to Cape Mendocino. We

were fortunate to have access to an extensive gravity, magnetic

and bathymetric survey done in 1970 by the National Ocean Survey.

Sea. floor rocks were obtained by dredging (Fig. 1) on

Antipode and Seven-Tow expeditions of the Scripps Xnstitution, on

several U.S.G.S. expeditions of the R/V Kelez and R/V Bartlettand from previous workers (Hanna, 1952; Uchupi and Emery, 1963;

Martin and Emery, 1967) . Hoskins and Griffiths (1971) —hereafter~ abbreviated as (H-G) —published structural interpretations of

shelf basins based on Shell Oil Company seismic profiles, dartcores, and well data. The data were not available to us, butwe have used their published maps and cross sections for age

control whenever possible.

For convenience of'resentation of the geophysical resultsand structural interpretation we divide the Central Californiacontinental margin into three regions: 1) Point Arguello toMonterey (34 to 36.5'N); 2) Monterey to Pt. Reyes (36.5 to 38'N);

3) Pt. Reyes to Cape Mendocino (38 to 40.5'N).

GEOPHYSICAL RESULTS

Point Arugello to Monterey

The dominant structural features of this part of the conti-nental margin'are the Santa Lucia bank and the Santa Maria and

Sur basins (Fig. 2). The bank is a broad high bounded on the

Gast by the Santa Lucia bank fault (Figs. 2 and -3) and on the

west by the top of the continental slope (see profiles 16-28,

Fig. 4).

The Santa Maria basin offshore lies between the Hosgri and

Santa Lucia bank faults (Fig. 2). The Sur basin is continuous

~ li ~ ~

h

with the Santa Maria, is bounded by coastal 'faults on the east

(Fig. 3), and sediment thins westward against the northern

part of Santa Lucia bank (Fig. 5,'2-L10).. The basins and bank

make up the Arguello Plateau (Uchupi and Emery, 1963). The

structural development of the region was discerned from the geo-

physical data, but the timing of tectonic events relies on data

from the geology of the onshore Santa Maria basin, offshore

drilling by oil companies (H-G), and dredging.

The Sur basin (Figs. 2, 3) is crossed by profiles L2-L10

(Fig. 5,) and has greatest sediment thickness in profile L6. The

ediment thickens eastward, with more than. three kilometers of

sediment very near the coast. The shelf is narrow here, and isprobably bounded on the east by a fault. The fault is suggested

by the vertical offset in Franciscan rock that probably underlie

the Sur basin offshore, and are exposed along the coastline, an

offset of at least four kilometers. The fault is also sugge ted

by a steep gravity gradient (Fig. 6) .

The near absence of deformation in these basin strata, and

the ease of acoustic penetration suggests that the layered section

on line L6 is largely of late Cenozoic age. H-G (1971) interpretthe base of the layered section to be lower Miocene. An uncon-

formity occurs within the section in line L2'(Fig. 5) but itsage is not known.

The Santa Maria basin is developed on lines L12 to L20, and

in many profiles sediment thickness is greatest at either edge

of the basin (see lines L16, L18, L22, L24, L26), as sediment

wedges thicken toward and terminate against the faults that

N

bound the basin. At least two unconformities are seen in lines

L14 to L28, especially well displayed in lines L16 and L20

(Fig. 4). The lower unconformity probably separates Miocene and

younger rocks from pre-Miocene rocks. The upper unconformity

may be late Miocene or Pliocene. An unconformity separating

early Tertiary from late Cenozoic (undated) rocks is beautifullydisplayed on lines L20, L22 and L24.

The Santa Lucia bank fault forms the western boundary of the

basin for about 150 km. The fault has its greatest physiographic

expression in line L20 (Fig. 4) where the 'sea floor is offsetabout 150 m. To the south the fault, nearly intersects a west

trending fault that bounds the north side of the channel islands

platform (Fig. 3) . However, the relation betvreen these faults isnot clear.

The east side of the basin is bounded by the Hosgrifault'Nagner,

1974), which can be recognized as a major*basement offseton the inner parts of lines L16 to L26. Shallow water depths and

ringing multiple reflections in some profiles act. to obscure the

structure. The Hosgri fault is probably seismically active. An

earthquake of magnitude 7.3 occurred in the vicinity of southern

Santa Maria basin in 1927, and Byerly (1930) reports that a tsunami

occurred along the coast of southern California following the

earthquake. Recent relocation studies (Gawthrop, 1977) place the

1927 epicenter at the southern end of the Hosgri fault.The Hosgri fault trends northward toward the San Simeon fault

on land and is probably continuous with it. Hall. (1976) presents

evidence for right lateral offset of 80 km to 100 km by matching1

geologic sections at San Simeon west of the fault and Pt. Sal,

80 km south and on the east side of the IIosgri fault. The

section is Jurassic through Pliocene and rests on Jurassic

ophiolite (Hopson and others, 1973). The exact location and

behavior of the Hosgri fault between San Simeon and Point Sur

is uncertain, but the fault is probably continuous and may

continue north to or be en-echelon with the San Gregorio fault,described below.

Basement rocks appear to directly underlie upper Cenozoic

deposits in the central part of the Santa Maria basin. ProfilesL16 and L18 show an arched basement reflector which correspond

with a gravity high and magnetic anomalies of up to 200 nT

(Fig. 7). A crustal model fitted to gravity data on line L18 issatisfied by a high density (2.85 gm/cc in this model) block inthe central part of the basin (Fig. 8).

Shallow basement beneath the basin is indicated by pairedmagnetic anomalies that are elongated parallel to the basin butconfined between the Hosgri and Santa Lucia bank faults (Fig. 7) .

The western anomaly is positive (> 100 nT) and the eastern isnegative (> -100 nT). The negative magnetic anomaly coincideswith the high density block and may b'e caused by basaltic x'ocks

of the Franciscan assemblage —perhaps part of the Pt. Sal ophio-lite described by Hopson and others (1973).

It now appears critical to drill the section over this reflectorto see whether it. is similar ox different. from the sections matched

by Hall across the Hosgri-San Simeon fault as a test of whether those

sections are truly offset 80 km or have continui ty offshore.

\I

~ 4 ~ ~

~ ~

Just east of the Hosgri fault is a series of NW-trending

faults that strike into the Hosgri at an angle but do not cut, the

large fault. Some of these small faults possibly cut. Holocene

sediments (Wagner, 1974), suggesting that both fault trends may

be active.

The age of the Santa Maria basin is repor ted to be latemiddle Miocene on the basis of drilling by Shell Oil Company (H-G) .

This age dates the relative uplift of Santa Lucia bank on the

western margin of the basin. Woodring and Bramlette (1950) 'eport.that marine deposition in the present onshore part of the basin

begain in the middle Miocene with the Pt. Sal formation. Marine

conditions continued there through Pliocene time and major deforma-

tion occurred in the Pleistocene.

Local compressional deformation is seen in Santa Maria basin

offshore. Figure 9 (profile LDM in Fig. 1) shows a large fold ofsedimentary rock buttressed against a basement. block on its east

side. The structure may have resulted from local shear between

basement rocks.

Santa Lucia bank forms a smooth topographic surface but has

a complex internal structure. The block faulted style of the

bank led H-G to postulate rigid granitic basement at depth. Seismic

profiles (Fig. 4, L20 to L28), however, show a complexly deformed

internal structure within the bank, suggesting an earlier phase

of deformation that was neither rigid nor blocklike. Thus the

bank has undergone at least two distinctly different styles of

de formation.

The older folding deformation of the bank is truncated by

an erosional unconformity, and in some lines (Pig. 4, L20 and

L24) the block faulting po t-dates the unconformity. If, as

discussed below, granitic rocks are present beneath the bank,

they are more likely pxesent as small fault slides than as a

continuous, rigid mass. Our profiles do not show a continuous

acoustic basement beneath the bank.

Three dredge hauls, D4, D5'nd D7, were taken on the bank.

Dredge haul (D5) was taken on a faulted outcrop on the east side

of Santa Lucia bank, crossed by profile L26 (Fig. 4). This

latter dredge recovered well rounded boulders and cobbles indica-

tive of significant transport prior to deposition, and also some

rock fragments, assumed to be local bedrock. 'he most abundant

transported boulders were meta-conglomerate, meta-sandstoneg

argillite, and mafic volcanic rocks. In-place rocks included

pholad-bored granitic sandstone and calcarenite, chert, and one

piece of actinolite schist. The schist was very angular and'I

easily broken and probably could not have survived appieciable

transportation. David Moore (pexsonal commun., 1971) dredged

glaucophane schist very neax this location. Dredge 4, located on

line L16 (Figs. 1 and 4), recovered several rounded cobbles ofquartz monzonite and quartz diorite. The most common rock type

recovered was granitic sandstone, with lesser amounts of pholad-

bored phosphorite, some siltstone, and mafic volcanic rock. The

sandstone, siltstone, and phosphorite were most probably in place.

The granitic cobbles, were transported an unknown distance. In

dredge D7, located on profile L28 (Figs. 1 and 4), soft granitic

sandstone was the dominant rock type recovered. The sizeand'ngularityof the granitic sandstone indicate that it was in

place. individual grains are angular to subangular, implying

rapid deposition with little reworking. Quartz and feldspar

commonly show undulatory extinction, and the micas are deformed,.

suggesting that the rock has undergone a significant shearing or

flattening deformation. The sandstone is similar to that found

within the Franciscan assemblage, which also is quartz rich,angular to subangular, and internally sheared (Bailey and others,

1964) .

The granitic cobbles and sandstone could have had either a

local (favored by H-G) or a distant source. Local source bodies

could be either intrusions or fault slivers.' Distant. sources

could be from the Salinian block (generally considered to be an

offset slice of Sierra Nevada granitic-metamorphic basement,

bounded by .the San Andreas and Sur-Nacimiento faults) .

At the base of the continental slope, all profiles show a

basin with 2 km or more of sediment fill. Profiles 16; 20, 22

and 28 show a basement, reflector passing below the lower part ofthe continental slope. Xn line L20, basin strata overlap

continental slope debris.. The same relations occur in line L28,

but here several hundred meters of strata above the basement

reflector pass under the slope debris. ln line L22 the structureis partly obscured by a small fault block at the base of the

slope. These observations suggest that no tectonic dislocationhas occurred along the lower part of the continental slope during

deposition of the upper two thirds of the basin sediment.

~ ~

An inactive, northwest-trending fracture zone offsets mag-

netic anomalies, questioningly identified as anomalies 7 and 8,

approximately 30 m.y. old by Atwater (1970) . The fracture zone

is marked by a ridge that provides further evidence for the

"stability of the lower slope region '(Figs. 3; 4, lines L18, L20,

L22, and L24; Fig. 7) . The ridge extends onto the lower part of

the continental slope in line L24, and dredging at this location

yielded dominantly fine-grained olivine basalt and manganese

nodules. These. rocks (D6, Figs. 1 and 4) are quite unlike allothers taken on this margin and are clearly representative of a

seamount or volcanic ridge. The dredge samples indicate that the

fracture zone ridge extends to the continental slope.

No appreciable lateral offset has occurred between the vol-canic ridge on the slope and the offshore fracture ridge if thiscorrelation is meaningful. The age of the ridge can be no older

than the sea floor on either side (about 25 to 30 m.y.). 1f the

ridge formed close to the time of sea floor development, the

most probable case, then little or no lateral offset has

occurred along the Santa Lucia escarpment since the Pacific and

American plates came into contact in the middle Tertiary (Atwater,

1970; McKenzie and Morgan, 1969) .

Monterey to Pt. Reyes

The dominant structural feature of the Monterey Bay area

is the San Gregorio fault (H-G, 1971; Greene and others, 1973)

which can be followed northward and offshore from Ano Nuevo Point

to intersect the San Andreas fault system off San Francisco,

giving a measured length of 150 km from south of Monterey to San

Francisco. The San Gregorio fault probably separates graniticbasement rocks on the east in Monterey Bay from non-granitic

rocks to the west (Martin and Emery, 1967; Greene and others,

1973) . East of the fault is a series of northwest-trending. faults

that do not cross the San Gregorio fadult. Earthquake studies

show that both these NN trending faults and the San Gregorio

fault are seismically active and first motion studies show thatboth are undergoing right slip (Greene and others, 1973). This

pattern is strikingly similar to that developed east of the Hosgri

fault (Wagner, 1974; Gawthrop, 1977). Furthermore, the San

Gregorio fault may be the northward continuation of the Hosgri-

San Simeon fault zone described above. Xf this suggested continuity

is proved correct, the aggregate length of the San Gregorio-Hosgri

fault zone approaches 400 km.

The San Gregorio appears to offset granitic basement terranes

at least 90 km (Silver, 1974) and Miocene and older rocks as much

as 90 to 115 km (Graham, 1976; Graham and Dickinson, 1977) . TheI

suggested offset of the San Gregorio fault is, within the limitsof error, equal to the suggested offset of the Hosgri fault,greatly increasing the probability that. they represent a single,continuous fault zone.

Two ridges and two basins lie west, and northwest of Santa

Cruz. 'he Farallon ridge is composed of quartz diorite at the

Farallon islands and appears to intersect the coast north of Ano

Nuevo Point. The ridge can be traced continuously in seismic

profiles as far north as Point Arena (Fig. 2), and shows clearly

15

as a high on the gravity map (Fig. 6). The free-air anomaly

reaches 50 mgal north of tho Farallon islands and drops to nearlyzero southwest of Half Moon Bay. This gravity low along

the'idge

may mark an old erosional or tectonic notch. A pronounced

positive magnetic anomaly is mapped over the southern part ofthe ridge ( ~ ig. 7). The northward extension of this magnetic

high along the Farallon ridge is less intense and cannot be

contoured becau e the available profiles are dominated by relativelystrong, and as yet uncorrected effects of diurnal variation. The

magnetic high can be recognized from profile to profile, however.

The gravity anomaly is most pronounced west of San Francisco and

Pt. Reyes where the magnetic anomaly is least developed. The

ridge as structurally defined does not represent simply the surfaceexpression of granitic basement. For example, line N23 (Fig. 10)

shows granitic rock between two faults on the upper continentalslope. The rest of the ridge in this profile is underlain by

uplifted sediments of Miocene and younger age,'nd Upper Cretaceous

sedimentary rocks, which probably appear as acoustic basement inour reflection profiles, crop out north of Ano Nuevo where theridge appears to intorsect the coast.

East of this ridge the Bodega basin locally contains more

than 2 km of late Cenozoic sediment. The east margin of the basinis formed by high angle reverse faults, from the Pt. Reyes faulton the north to a narrow fault zone off Half Moon Bay. ProfilesK44 and K66 (Fig. 11) show a buried unconformity, below which

sediments aro faulted and more tightly folded than the post uncon-

formity strata. Comparing our profiles with the H-G drilling ages,

the unconformity is middle Miocene. An H-G cross section

southwest from Bodega Head shows thin 'lower to middle Miocene

strata over the central part of the basin with westward

thickeni ng. This structure indicates that the central part ofBodega basin stood high in the lower and middle Miocene. Upliftof the western margin (the Farallon ridge) and subsidence ofthe basin. commenced in about the late middle Miocene.

The Santa Cruz high lies off Santa Cruz and southwest of the

Farallon ridge, and between the two ridges lies Outer Santa Cruz

basin (Fig. 2). Both the Santa Cruz high and outer basin plunge

northwest (lines Sl-3, Fig. 12). To the north the high diminishes

and the western margin of the basin is formed by Pioneer and

Guide seamounts. A dredge haul and core (AD21 and ACD ll}recovered mafic volcanic rock from the Santa Cruz high.

Outer Santa Cruz basin attains a thickness of at least 3 km.

The lower layers on the west side of the basin are gently up-

turned against the Santa Cruz high in line S2 (Fig. 12), but theA

upper 1 km of section abuts the ridge with no sign of distortion.Probably no vertical movement of the ridge has occurred inQuaternary or late Pliocene time, based on estimated sediment ages

in seismic profiles, but earlier uplift is indicated. The eastern

margin of,the basin appears fault controlled (see lines K68, K93,

and S1-4) but faulting affects only the deeper layers and probably

has not been active since late Miocene time. This structure con-

trasts with the basin edge faults bounding Bodega, Santa Maria and

Sur basins, which show Pleistocene and in some cases Holocene

'ctivity.

Dredging on the continental slope west of Farallon ridge

has yielded rock and sediment of. Miocene and younger age (Hanna,

1952; Uchupi and Emery, 1963; Curray and Silver, 1971; Silver

and McCulloch, 1973, unpublished data) ..Reflection profiles

(Kl, K44, Fig. 11) show Miocene and younger strata passing

smoothly across the continental slope out onto the abyssal plain.

The sediments are cut by submarine canyons, valleys and slumps,

but show little or no sign of tectonic activity. In some profiles

(Kl, K44, K66), coherent reflections below the younger, regularly

bedded sediment blanket may denote a folded sedimentary sequence

representing a tectonic environment quite different from the

present one. Some of these deep, irregular reflections are asso-

ciated with volcanic rocks (K93, Sl, S3), as interpreted from

marine magnetic anomalies. Atwater (1970) suggested that in

early Ter tiary time the Central California area was a region o fcrustal subduction. We suggest that the folded sedimentary

sequence seen on the continental slope in lines Kl, K44, K66, W19,

and lines 'L-18 to L28 was deformed by subduction and sediment.

offscraping in the early Tertiary episode. Subduction appears

to have ceased before Miocene time because Miocene and younger

strata are not deformed.

Pt. Reyes to Cape Mendocino

Horth of Pt. Reyes the Bodega basin is bounded on the west

by the Farallon ridge, which is faulted in this region, and on

the east by the Pt. Reyes fault. The Pt. Reyes fault appears as

a sharp flexure in the seismic profiles (see line W23, Fig. 10)

and H-G map it as an east-dipping reverse fault.The Bodega basin in this area resembles the Santa Maria basin

offshore in that both are bounde'd by down-to-basin faults. As

with the Santa Maria basin, the Bodega and Outer Santa Cruz basins

originated in late middle Miocene time (H-G) . Bo«ga basin

narrows northward as the Farallon ridge approaches the coast.

Three acoustic units can be distinguished, within Bodega

basin which are separated by basin-edge unconformities (profile

W23, Fig. 10). The lowermost unit is most. deformed and is

probably upper Miocene, based on sections by H-G. The reflectors

within this unit are parallel, demonstrating that uplift of the

'basin margins or relative subsidence of the basin began in latest

Miocene or early Pliocene. The overlying Plio-Pleistocene beds

are less deformed and the uppermost layer shows no evidence of

tilting against the ridge. Approximately two kilometers of

Pliocene vertical relative uplift are indicated for the Farallon

ridge ~

Granitic rocks crop out as far north as Bodega Head within

the Salinian block. No granitic basement is reported north of

Bodega west of the San Andreas fault, but the extent of the

Farallon ridge may indicate such basement as far north as Point

Arena. The ridge appears as a block-like uplift in profiles Kl

and K3 (Fig. 11), and in W19 through W26 (Fig. 10) . Faults

bound one or both sides of the ridge in these profiles and strata

of the west side of Bodega basin are uplifted. In lines W18,

W17 and N16, an unconformity truncates both the ridge and the

basin strata, and Pleistocene deposits prograde across it. The

~ ~

~ ~

block structure of the ridge is not evident in these profilesand the upper surface of the ridge is not a hard reflector,as it is farther south. Thus, the ridge structure extends as

far north as Point Arena, but gran'itic basement is followed

with confidence only to approximately 38'30'N, or 50 km south ofPoint Arena. It remains uncertain, therefore, whether graniticrocks continue at depth under the ridge to Point Arena or ar'

T

absent north of 38'30'N and sedimentary rocks make up the body

of the ridge.

Evidence suggestive of offshore granitic basement north ofBodega was presented by Wentworth (1968) in the Gualala area

where he identified coarse clastic Cretaceous sediments derived

from the southwest. Such rocks under the northern part of the

Farallon ridge could provide such a source.

The sea floor off Point Arena is exceptionally complex. The

,Farallon ridge ends offshore of the point, but its northern terminus

is not well defined. The San Andreas fault bends to a more northerlytrend north of Point Arena, and northwest of the point'is a series

of complex northwest trending folds and faults (Fig. 3) in lateCenozoic strata. These str'ata are part of the Point Arena basin

of H-G.

On the west side of the basin a broad, low structural ridge,the Oconostota ridge increases in width northward. The ridge is

I

seen underlying a broad, low terrace near the base of the con-

tinental slope (Fig. 10).'ine WX (Fig. 13) follows the „ridge

crest and shows the irrcgular complex structure of the ridge

underlying the fairly uniform layering of late Cenozoic strata above.

The, basement rock of Oconostota ridge crops out on the

north flank of Noyo Canyon (Pig. 10, line W8) and a dredge haul

at this location yielded abundant graywacke. The rock is weakly

foliated to highly sheared in thin section and shows chloritealteration of the groundma s. It is poorly 'fossiliferous but

contains "a few non-diagnostic Mid-Eocene to Oligocene nanno-

fossils" (T. R. Worsely, written commun., 1973) .

Site 173 of leg 18 of the Deep Sea Drilling Project (DSDP)

was drilled on the western flank of the ridge. The hole 'pene-

trated a complete section of marine strata from Pleistocene

through lower Miocene or upper Oligocene(?) and terminated inandesite (culm, von Huene and others, 1973). The reflectionprofiles show that these Miocene and younger strata pass smoothly

across the base of the continental slope and drilling indicatesthat depositional conditions were quiet in this area back tothe early Miocene.

Recovery of deformed early Tertiary sedimentary rock and

of andesite from Oconostota ridge demonstrates some of'thelithologic complexity of the ridge. In line W18 (Fig. 10) the

west flank of Oconostota ridge near the base of the slope abuts

the acoustic'-basement reflector beneath the sediments west ofthe ridge and suggests that the contact between pre-Miocene

continental slope material and the oceanic crust was tectonic.These observations imply that the Oconostota ridge was formed

under tectonic conditions 'that have not been active since the

early Miocene.

J-20

'

The Point Arena basin as described by H-G, is bounded by

the San Androas fault on the east, Point Arena to the south,

the Mendocino fault to the north, but is ill def ined on itswc tern margin. >le consider the Oconostota ridge to form the

western margin. The structure of this basin changes markedly

from south'he north. profile N13 (Fig. 10) off Point Arena

hows a section of de Qrmed deposits of probable Miocene age

covering much of the;... rgin. This material is overlain uncon-

formably in the hei f a d upper slope area by prograding latestCenozoic deposits. U.-,der the shelf the unconformity dips uniformlyeastward to location - where it appears to terminate against, a

fault with significa."." vertical offset-Zn line Nll fol=-= Miocene rocks are truncated by an uncon

formity which is in -- . folded.'I

(Fig. 10, line Nll, 'o 20 km)

Beneath the shelf edge is,a basin

with thick deposits above the

mity H-G r:=-= =aults with. several kilometers of verticaloffs« on either sid=- „-= this basin. The basin is seen on profilesN9 th'rough N12. The -=~logy east of the basin is complex andob «red by multiple --=lections on the seismic records. The

uppor unconformity p'= =ave widespread extent throughout theeastern «ge of the '==- ==~ and crops out or subcrops at depthsbetween one and two .'c= —..eter below sea level. Xf this inconformitresul«d from erosio-. =-; wave action, up to two kilometers ofsubsidencesu~ ~«nce of the ea~==-> margin of point ~rena basin may beinferred for guatern=- —.- "„ime.

~"ottom reflee---s are approximately parallel to the eea

a"«f Oconos-- —= ridge and minor faulting (line N8, Fig. 10)

occurs. Profiles farther north, Wl through W7, show minor

'. deformation of late Cenozoic deposits but older rocks are intern-

ally deformed (line NX, Fig. 13) . The surface of the older rocks

is irregular, and unlike the younger sediment, show no obvious

relation to erosional channeling.

A number of relatively tight folds and associated faultsI

trend northwest from Point Arena and die out approximately 50 km

to the north, where the continental slope becomes more gentle.'

major part of the deformation in this area, including the large

shelf-edge basin, the folded unconformity, and faults of large

vertical offset, are most, likely controlled- by tectonic processes,

although some deformation may be related to downslope movement of

sediment under the influence of gravity.

The San Andreas Fault Zone

The San Andreas fault changes orientation north of Point Arena

to a'ore northerly-trend and can be traced onshore just south ofPoint Delgada (Curray and Mason, 1967). South of Shelter Cove sixprofiles (4 not shown in Fig. 1) cross the San Andreas, which offsetsthe sea floor with the west side up, producing a shoreward facing

scarp. Another fault, two miles east has no sea floor offset. The

maximum observed vertical offset on the San Andreas fault scarp off-shore is 8 m, and the relief decreases southward. The general

displacement history of the San Andreas is right lateral slip, and

such movement would have produced east-side-up offset since the sea

floor slopes southward along the strike of the fault. Therefore the

observed west-side-up topographic offset must be due to verticalmovement.

J-22

23

'North of Point Delgada the location and character of the San

Andreas is unknown.' Nason (1968) mapped a number of shear zones on,

land between Point Delgada and Cape Mendocino but he could find no

evidence for recent movement on the zone" near Point Delgata. Un-

fortunately, the clear geomorphic evidence for 1906 faulting at Pt.

Delgada cannot be traced across this area (Lawson, 1908). This lack

of evidence may be the result of obliteration of such evidence by

extensive landsliding and mass soil movement that occur in this area;

or perhaps, the San Andreas does not extend onshore north of Point r

Delgada as a well-defined fault. Xn this regard, Beutner and Hansen

(1975) carefully examined the structure of the large inland shear

zones and determined a left..lateral sense of shearing, associated

with late Tertiary subduction. They also found, however, that NN-

trending structures just along the coastline showed evidence for rightlateral shear.

Detailed reflection surveys that we have made offshore between

Point Delgada and Cape Mendocino (not shown in Fig. 1) have no dis-covered definite evidence of faulting offshore between Cape Mendocino

and Point Delgado. Numerous acoustic 'irregularities on the nearshore

profiles may represent faulting, but the deeper structure is obscured

by multiple reflections. None of these irregularities can be traced

between profiles. Zf the San Andreas fault is expressed by a singletrace north of Point Delgada it may run along the beach. Seeber and

others (1970) show a very complex pattern of micxoseismic activity inthis region.

The northward bend of the San Androas presents an interestinggeometrical puzzle. A fault-fault-trench triple junction like the

J-23

24 I~

Mendocino is unstable unless one fault is on a straight linewith the trench (subduction zone) (Fig. 14). The Mendocino shouldbe unstable because the San Andreas fault and the subduction zone

are not aligned. However, north of Point Arena the San Andreas

bends northward and then, at Point Delgada, northwestward. This

bending raises a serious problem in that the northerly trend,between Point Arena and Point Delgada, should be associated withextension across the. fault, as indicated in Figure 14d. . Possiblysubsidence of the continental margin in this area, as seen by

deep unconformities, a gentle continental slope, and a narrow

shelf is a manifestation of extension. However, instead ofchanging the geometry of the triple junction to acquire a new

stability configuration (as in 14c), the plate boundaries. appear to1

be adjusting to maintain stability of the older geo'metry.

TECTONXC DEVELOPMENT OF THE CONTINENTAL MARGIN

The s true tural development of the continental margin ofCentral California provides important: constraints for any . scenarioof the tectonic evolution of the western United States. The

structure of the lower part of the continental slope in thisregion shows well layered Miocene and younger'trata smoothly

covering an irregular, hummocky "basement" that is at least inpart, composed of deformed Paleogene sedimentary and volcanicrocks. This structural superposition is interpreted to indicatePaleogene deformation, probably related to subduction of the

Farallon plate (Atwater, 1970), followed by Miocene to Holocene

i ~ g ~ ~ rC

tectonic quiescence along the lower part of the continental

slope, Evidence for Miocene and younger quiescence is provided

by the presence of a volcanic ridge along an early Pliocene

transform fault (Fig. 3) that extends undeformed from the oceanic

crust onto the continental slope west of Santa Lucia bank.

Because the ridge shows no off et at its junction with the slope,no significant Miocene or younger shear can have occurred on

the lower part of the slope if this correlation is correct.In contrast, abundant evidence is seen for extensive faulting,both horizontal and vertical, along the central and inner partsof the continental margin.

An important structural feature for deciphering tectonicmovements in this region is the Faxallon ridge. The graniticintrusives along the offshore ridge indicate that it is the

probable offshore extension of the Salinian block, the sliver ofgranitic and metamorphic basement lying between the San Andreas

and Sur-Nacimiento fault zones (Page, 1970). The Salinian block

is generally interpreted as a slice of Sierran-type basement

that has been displaced northwestward'long the San Andreas

fault system (Efamilton, 1969; Page, 1970; Crowell, 19G2) although

alternative hypotheses have been suggested (kIsu, 1971). If the

first hypothesis is correct, then the northern extent ofgranitic basement rocks records the total horizontal offsetalong the San Andreas fault system. From the northernmost extentof recognizable granitic basement west of the fault to itsnorthernmost extent east of the fault, the minimum slip appears

to be 550 km, and from the northern extent of Farallon ridge

26

k

morphology the maximum slip is 600 km (Pig. 2a) (Silver and

others, 1971) . A total offset, of 550 to 600 km along the San

Andreas faul t was first suggested by Nentworth (1968) and hisevidence was further substantiated by Ross (1972), based on

identifying offset source terranes for conglomerates within the

Gualala basin.

How and when this offset occurred is only partly resolved.

Right slip displacement of 300 km post 22 m.y.a. has been docu-

mented on the central part. of the San Andreas fault between San

Francisco and the Transverse Ranges (Huffman, 1972; Matthews,

1976) and Nilsen and Clarke (1975) documented no offset, on thatsegment from 45 to 22 m.y.a. Xt is important. to distinguishover what segments the offsets apply, because the availableinformation can be explained in several ways. One is a two-stage,

single fault model (Suppe, 1970) giving about 300 km of lateCretaceous to early Tertiary offset on the San Andreas fault,followed by a second, Miocene and younger offset, of another 300

km on the fault.. A second model is a single stage-multifault history in which

greater offsets can occur on the northernmost segment of the San

Andreas than farther south due to slip on other, subparallelfaults west of the San Andreas.

The recent studies of the San Gregorio-Hosgri fault zone

indicating 100 + 15 km of right.-lateral offset .support the multi-fault model, although the offset mapped to date is insufficientto prove a single stage history. Graham (1976) mapped a maximum

of 35 km right slip on the Rinconada fault bringing the maximum

documented Miocene.and younger offset on the San Andreas fault~sstem to approximately 450 km.

Activity on the San Gregorio fault may'play a major role in

partitioning strain buildup in the Central California region.

Studies of lateral offset of fences, roads, railroads and other

linear markers after the San Francisco earthquake of 1906 showed

common evidence for offsets of 5 m (16 ft) or more north of San

Francisco, but only 2 1/2 to 3 m (8 to 10 ft) south of San

Francisco (Lawson, 1908) . One explanation of this difference isa lesser strain buildup on the San Andreas to the south because

of slip on the San Gregorio fault. The Hayward-Calaveras faultzones may also relieve strain buildup on the San Andreas system,

but it is not clear why slip on this fault zone should selectivelypartition the strain differently north and south of San Francisco

(see Fig. 3).

The remaining 100 (+) km of basement offset may be explained

by Miocene and younger undiscovered slip along other faults cuttingthe Salinian block. Their discovery would prove .the Johnson-

Normark hypothesis. Alternatively, approximately 100 km of lateCretaceous to early Paleocene offset may have occurred on the

San Andreas fault, as suggested by Silver and others (1971) to

explain the development of the Gualala basin in latest Cretaceous

time. They proposed a rhombochasm opening of an elongate basin

to explain the basalt floored basin filled with. very thick,coarse elastic sediments (Nentworth, 1968). An early TertiarySan Andreas fault is also favored by Nilsen and Clarke (1975) to

explain early Tertiary paleogeography and basin development in

28~ W ~

Central California.

Development of the Basins

The results of drilling in the basins which suggest a

nearly synchronous origin of the central California basins inmiddle to late middle Miocene time (roughly 10 to 14 m.y.a.),place tight constraints on hypotheses for the origin of the basins.

For example, an origin related to a southward migrating tripleV

junction must be eliminated. here because the timing of this migra-

tion was over a period 8 to 10 m.y; long from about 29 to 20 m.y.a.

in this region. The age data give no indication of an age

progression in the origin of these basins and the timing (10-14'

m.y. 'vs. 29 to 20 m.y.) is between 6 and'20 m.'y. too late for thismodel. This paper does not deal with the development of the

southern California Borderland basins, but most of them apparently

developed in about the middle Miocene (10 to 15 m.y.a.) (Blake and

others, 1978) . According to Atwater, (1970) the migrating triplejunction was in the vicinity of the Borderland in middle. Miocene

time as well. Thus the southern California Borderland, while much

more impressive in basin development than central California, does

not offer the opportunity to distinguish between a migrating triplejunction vs a mechanism involving near synchronous development ofCalifornia offshore basins.

~To investigate the possibility of a change in plate motions

being responsible for the near synchronous development of the basins

we reconstructed the history of Pacific-. America motion in much the

same way as Atwater and hiolnar (1973), and then computed average

J-28

~, ~

movement vectors at 36'N, 121N, and 33 N, 119M for the intervals0-4.5, 4.5-10, 10-21, 21-29, and 29-3S m.y. The results are

shown in Table 1.

Rotations were done in a reference frame fixed to North America

and in a restorative sense for the global circuit Pacific-Antarctic-Indian-African-North American plates. Data sources are

given in Table l. The thoro largest sources of error are in the

central Indian Ocean (Ind-Afr) and the central Atlantic Ocean (Afr-NAm) because these rotations require 'the greatest amount of data

interpolation of sea floor magnetic anomalies. Tectonic hind- .

casting of this sort. can be improved upon only by more detail inthose regions.

In addition to the accelerated rate of movement in the lateCenozoic is the significant change of azimuth, especially after 21

m.y.a., 'or subsequent to the change along this continental marginfrom subduction to transform motion. At 36N, the azimuth is

339'or

21-10 m.y., 328'ox 4.5-10 m.y., and 321~ for 0-4.5 m.y.'I

4These successively more westerly-directed movements of the Pacificrelative to the North American plate may have produced extensionalstrain along the continental margin, perhaps culminating in the „-

middle Miocene, about 10-14 m.y.a. The extensional, strain was

manifested in the formation of the basins along the Central Californiamargin, and perhaps those of the southern California borderlandas well.

Since the vectors are computed from finite rotation poles they

represent an average value for the time period, but not necessarilythe actual direction at any specific time. If it were possible to

J-29

30\ 'q „ i ~

compute rotation poles for small time intervals we might discoverthat the pole of rotation between the Pacific and North American

plates has been changing continually during the last 30 m.y. Such

small but continual changes in direction and rate of plate move-

ments may result in the development of a,complex structuralgeometry in the area of the plate boundary, as observed alongCentral California continental margin, and in fact, along the

/entire western margin of the United States.

CONCLUSIONS

Marine geological and geophysical observations support thegeneral model of Atwater (1970) of early Tertiary subduction

\

followed by Neogene translational shear along the Central Californiacontinental margin. Early Tertiary rocks form irregular structural

I,surfaces and show relative1y intense deformation. Neogene strataare well layered, mildly warped and cut by high angle faults.Large shelf basins formed along the margin in late middle Miocene

time, probably from a component of extensional strain during platetranslational movements. Plate tectonic analysis using finiterotations around a global circuit: Pac-Ant-Ind-Afr-NAM, shows a

change in average Pac-NAM movement during about middle Miocene toa more extensional sense of shear. This change could be responsiblefor the synchronous opening of the basins. This analysis shows a

8

change in pole of relative movement for each interval, and suggeststhat instantaneous movement between the Pacific and North American

plates may have changed continually over the past 30 m.y.1

31

Study of the continental margin provides constraints on thc-

offset history of the San Andreas fault system. The northward

extent of gr'anitic basement of the Salinian block, as traced by

the Farallon ridge, limits basement offset to between 550 and

600 km. Of this figure, 300 km occurred on the San Andreas fault

in Neogene time between San Francisco and the Transverse ridges

and up to 150 km on the San Gregorio-Hosgri fault and the

Rinconada fault south of San Francisco. These values add to

the San Andreas offset north of San Francisco.

Early Tertiary paleogeographic and provenance studies by

Nilsen and Clarke (1975), as well as the difference between

measured fault slip and basement offset are best explained ifsome offset on faults within the Salinian block occurred during

latest Cretaceous to Paleocene time. Thus a two-stage, multifaultmodel for Salinian offset is preferred,. with about 100 km slipin latest Cretaceous to Paleocene and about 450 km post-22 m.y.

,Granitic boulders dredged from Santa Lucia bank have two

possible origins. Xf the boulders were locally derived,.granitic

fault slivers must occur west of the Salinian block and the simple

offset model presently accepted by many California geologists must

be revised. Alternatively, the boulders may have been transported

100 km or more from source areas in the Salinian block.

~ .

'C~ '

'I

Table 1. Pacific-North America Finite Motions*

36~N, 121 O' 33'N, 119 W

Time Intervalm.y.

RateAzimuth (1) (cm/yr) Azimuth (1)

Hate(cm/yr )

(2) 4. 5-0

(3) 10-4. 5

(4) 21. 2-10

(4) 29. 2-21. 2

(4) 38-29. 2

321

328

339

32'1

320

5.6

4.5

3.2

3.8

1.7

319

326

335

319

318

5.6

4.6

3.1

3.9

1.8

*Summation of the circuit: Pacific-Antarctic-Xndian-African-North American plates.

(1) Degrees positive clockwise from. north.

(2) All rotations from Minster and others (1974) .'II

(3) Pac-Ant from, Molnar and others (1975) . All others from

Minster and others (1974) .

(4) Pac-Ant: Molnar and others (1975) .

Ant-Xnd: Weissel and oQ>ers (1972) .

Xnd-Afr: McKenzie and,Sclater (1971) .

Afr-NAm:, Pi tman and Talwani (19 72) .

I~ ~

32

REFERENCES CITED

Atwater, T. M., 1970, Implications of plate tectonics for the

Cenozoic tectonic evolution of western North America:

Geol. Soc. America Bull., v. 81, p. 3513-3536.

Atwater, T. M. and Molnar, P., 1973, Relative motion of the

Pacific and North American plates deduced from sea floorspreading in the Atlantic, Indian and South Pacific oceans:

Kovach, R. L. and Nur, A., eds., Stanford University Publica-

tions in Geol. Sciences, v. 13, p. 136-148.

Bailey, E. H., Irwin, W. P., and Jones, D. L., 1964, Franciscan

and related rocks, and their significance in the geology of

western California: Calif. Div. of Mines and Geology Bull.

183, 177 p.

Beutner, E. C. and Hansen, E., 1975, Structural evidence of plate

interactions from continental rocks, Cape Mendocino to Shelter

Cove, Cali fornia (abs. ): Geol. Soc. Amer. Abs. with Programs,

v. 7, no. 7, p. 997.

Blake, M. C., Jr., Campbell, R. H., Dibblee, T. W., Jr., Howell,

D. G., Nilsen, T. H., Normark, W. R., Vedder, J. G., and

Silver, E. A., 1978, Neogene basin formation and hydrocarbon

accumulation in relation to the plate tectonic evolution of the

San Andreas fault system, California: Am. Assoc. Petroleum

Geol. Bull. (in pxess) .

Buchanan-Banks, J. M., Pampeyan, E. H., Wagner, H. C., and

McCulloch, D. S., 1978, Preliminary map showing recency of

faulting in coastal south-central California: ,U. S. Geol.

Survey Misc. Field Studies Map MF-910, 3 maps at 1:250,000.

Byerly, P., 1930, The California earthquake of November 4, 1927:

Seismol. Soc. America Bull., v. 20, p. S3-66.

Crowell, J. C., 1962, Displacement along th'e San Andreas fault;Cali fornia: Geol. Soc. America Spec. Paper 71, 61 p.

Curray, J. R. and Nason, R. D., 1967, The San Andreas fault northof Point Arena, California: Geol. Soc. America Bull., v. 78,

p. 413-418.

Curray, J. R., and Silver, E. A., 1971, Structure of the continentalmargin and distribution of basement rock types of centralCalifornia (abs.): Geol. Soc. Amer. Abs. with Programs, v. 3,

no. 2, p. 106-107.

Gawthrop, W. H., 1977, Seismicity of central coastal California(abs): Geol. Soc. America Abs. with Programs, v. 9, no. 4,

p. 422.

Graham, S. A., 1976,. Tertiary sedimentary tectonics of the centralSalinian block of California: Ph.D. thesis, Stanford Univ.,510 p.

Graham, S. A. and Dickinson, W. R., 1978, Evidence for 115 km ofright slip on the San Gregorio-Hosgri fault trend: Science,

v. 199, p. 179-181.

Greene, H. G., 1970, Geology of southern Monterey Bay and itsrelationship to the ground water basin and salt water intrusion:U. S. Geol. Survey open file report, 50 p.

Greene, H. G., Lee, W. H. K.', NcCulloch, 'D. S. and Brabb, E. E.,II

1973, Faults and earthquakes in the h1onteroy Bay region,California: hiisc. Field Studies llap NP-518.

J-34

~ ~

Hamilton, N., 1969, Mesozoic California and the underflow ofPacific mantle: Geol. Soc. America Bull., v. 80, p. 2409-2430.

FFall, C. A., Jr., 1975, San Simeon-EJosgri fault system, coastal

California: economic and environmental implications: Science,

-v. 190, p. 1291-1294.

Hanna, G. D., 1952, Geology of the continental slope off centralCalifornia: Calif. Acad. Sci. Proc., Fourth Ser., v. 27,

p. 325-358.

Hopson, C. A., Frano, C. J., Pessagno, E., and Mattinson, J. M.,

1973, Late Jurassic ophiolite at Point Sal, Santa Barbara

County, California (abs): Geol. Soc. America Abs. with

Programs, v. 5, no. 1, p. 58.

Hoskins, E. G. and Griffiths, J. R., 1971, FFydrocarbon potentialof northern and central California off hore: Am. Assoc.

Petroleum Geol. Mem. 15, v. 1, p. 212-'228.

Hsu, K. J., 1971, Franci can melanges as .a model for eugeo-

synclinal sedimentation- and underthrusting tectonics: Jour.

Geophys. Res., v. 76, p. 1162-1170.

Huffman, 0. F., 1972, Lateral displacement of upper Miocene rocks

and the Neogene history of offset along the San Andreas faultin central California: Geol. Soc. America Bull., v. 83,

p. 2913-2946.

John on, J. D., and Normark, N. R., 1974, Neogene tectonic evolu-

tion of the Salinian block, west-central California: Geology,

v. 2, p. 11-14.

Kulm, L. D., von Huene, R., and others, 1973, Initial Reports of

the Deep Sea Drilling Project, v. 18, 1077 p.

J-35

~ ~

Lawson, A. C., 1908, The California earthquake of April 18, 1906:

Report o f the S tate Earthquake Investigation Commission,

v. 1, 451 p.

Martin, B. D. and Emery, K. O. ( 1967, Geology of Monterey

Canyon, Cali fornia: Am. Assoc. Petroleum Geologists Bull.,v 51( p 2281 2304 ~

Matthews, V., XXX, 1976, Correlation of Pinnacles and Neenach

volcanic formations and their bearing on the San Andreas faultproblem: Am. Assoc. Petroleum Geologists Bull., v. 60,

p. 2128-2141.'

McCulloch, D. S., Clarke, S. H., Jr., Field, M. E., Scott, E. N.,

and Utter, P. M., 1977, A summary report on the regional

geology, petroleum potential, and environmental geology of the

southern proposed lease sale 53, central and northern Californiaouter continental shelf: U. S. Geological Survey Open FileRept. 77-593, 56 p.

McKenzie, D. P. and Morgan, N. J., 1969, The evolution of triplejunctions: Nature, v. 224, p. 125-133.

McKenzie, D. P. and Sclater, J. G., 1971, The evolution of the

Xndian Ocean since the late Cretaceous: Geophys. Jour. Roy.

Astro. Soc., v. 25( p 437 528.

Minster, J. B., Jordan, T. H., Molnar, P., and Haines, E., 1974,

Numerical modeling of instantaneous plate tectonics: Geophys.

Jour. Roy. Astro. Soc., v. 36, p. 541-576.

J-36

Molnar, P., Atwater, T. M., Mammerickx, J., and Smith, S. M. I'I

1975, Magnotic anomalies, bathymetry, 'and the tectonic evolu-

tion of the South Pacific since the late Cretaceous: Geophys.

Jour. Roy. Astro. Soc., v. 40, p. 383-420.

Nason, R. D., 1968, Geology of Cape Mendocino, Dickinson, N. R. and

Grantz, A., eds., Stanford University Publications in Geol.

Sciences, v. 11, p. 231-34.

Nilson, T. H. and Clarke, S. H., Jr., 1975, Sedimentation and

tectonics in the early Tertiary continental borderland ofcentral California: U.S. Geol. Survey Prof. Paper 925, 64 p.

Page, B. M., 1970, Sur-Nacimiento fault zone in California:Continental margin tectonics:

p. 667-690.

Geol. Soc. America Bull., v. 81I

Pitman, N. C. and Talwani, M., 1972, Sea-floor spreading in the

North Atlantic: Geol. Soc. America Bull., v. 83, p. 619-646.

Ross, D. C., 1972, Petrographic and chemical reconnaissance study

of some granitic and gneissic rocks near the San Andreas-

fault from Bodega Head to Cajon Pass, California: U. S. Geol.

Survey Prof. Paper 698, 92 p.

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seismicity and tectonics of coastal northernCalifornia: Seismol. Soc. America Bull., v. 60, p. 1669-1699.

Silver, E. A., 1974, Structural interpretation from free-air/

gravity on the California continental margin, 35'o 40'N (abs):Geol. Soc. America Abs. with Programs, v. 6, no. 3, p. 253.

J-37

Silver, E. A., Curray, J. R., and Cooper, A. K., 1971, Tectonic

development of the continental margin off central California:

. in Lipps, J. and Moores, E. M., eds., Geologic guide to the

northern Coast Ranges-Point Reyes region, California: Guide-

book, Geol. Soc. Sacramento Ann. Field Trip, p. 1-10.I

Suppe, J., 1970, Offset of Late Mesozoic basement terranes by theI

San Andreas fault sys tern: Geol. Soc. America Bull., v. 81,

p. 3253-3258.

Uchupi, E. and Emery, K. O., 1963, The continental slope between

San Francisco, Californi'a, and Cedros Xs., Mexico: Deep-Sea

Res., v. 10, p. 397-447.

Nagner, H. C., 1974, Marine geology between Cape San Martin and

Pt. Sal, south-central California offshore: U. S. Geol. Survey

Open File Report 74-252, 17 p.

Neissel, J. K. and Hayes, D. E., 1972, Magnetic anomalies in the

Southeast Xndian Ocean: Antarctic Oceanology XX: The

Australian-New Zealand sector, Hayes, D. E., ed., American

Geophysical Union, Nashington, D.C., p. 165-196.

Nentworth, C. M., 1968, Upper Cretaceous and lower Tertiary strata

near Gualala, California, and inferred large right slip on the

San Andreas fault: in Dickinson, N. R. and Grantz, A., eds.,

Proc. Conf. Geol. Problems of the San Andreas fault system:

Stanford Univ. Publications in Geol. Sciences, v. 11, p.130-143.'oodring,

N. P. and Bramlette i M N i 1950, Geology and paleontology

of the Santa Maria district, California: U. S. Geol. Survey

Prof. Paper 222, 185 p.

J-38

FIGURE CAPTIONS

Figure l. Track of geophysical cruises and geologic sample loca-

tions on the central California continental margin. Heavy

lines are seismic profiles illustratedin this paper.

Identification of seismic profiles by cruise:

W = Thomas Wa hington

K = Kelez

S = Bartlett 1972, leg 1

.L = Bartlett 1972, leg 2

LDM = Davis profileIdentification of samples by cruise:

D = Kelez Dredge

F = Kelez Dart Cores

ADC = Melville (Antipode) Dart Core

AD = Melville (Antipode) Dredge

7DS = Thomas Washington DartCore (7 Tow)

B = Bartlett Dredge

Figure 2. Map of structural features on the central Californiacontinental margin. Location of ridges, basins and major

faults. CM: Cape Mendocino; PA: Point Arena; PR: Point Reyes;

SF: San Francisco; M: Monterey; SS: San Simeon; PS: Point

Sal; PC: Point. Conception.

Figure 3. Map of faults and folds on the continental margin.

Figure 4. Line drawing interpretation of Bartlett seismic reflectionprofiles L16 to L20 across the Santa Maria basin.

J-39

Figure 5. Line drawing interpretation of Bartlett seismic reflec-

tion profiles L2 to L14 across the Sur and Santa Maria basin.

Figure 6. Free-air gravity map of the continental margin, from

35'o 40'North. Contoured from National Ocean Suryey

unpublished data. Contour interval 10 mgal.

Figure 7. Residual magnetic map of the continental margin and

oceanic crust to the west. Map is combined National Ocean

Survey data and Bartlett data.

Figure 8. Crustal model satisfying observed gravity for profileL18. 2.65 means 2.65 gm/cc. No scale exaggeration. East

is on the right.Figure 9. Reflection profile taken by D. G. Moore across the

ISanta Maria basin showing local folding of strata against a

"buttress" of acoustic basement. Labeled LDM on Figure 1.

Figure 10. Line drawing interpretation of Thomas Washington profiles

W6, 8, ll, 12, 13, 16, 18, 19, and 23. From Expedition 7-Tow,

leg 9B.

Figure 11. Line drawing interpretation of reflection profiles Kl,

3, 44, 66, 68, and 93, from the R/V Kelez.

Figure 12. Line drawing interpretation of 'reflection profilesSl-S4, from leg 1 of R/V Bartlett in 1972. Profiles cross

outer Santa Cruz basin and Santa Cruz high.

Figure 13. Line drawing interpretation of profile NX, takenalong'he

axis of Oconostota Ridge.

J-40

~ ~ ~

Figure 14. Geometry of hypothetical stable and unstable fault-fault-trench triple junctions, predicted new condition ofstability and generalized observed geometry.

a) Stable fault-fault-trench triple junction.b) Generalized unstable form of Mendocino triple junction.c) Predicted new position of stability = Ridge-Ridge-Ridge

.triple junction (this solution is from Clement Chas'e,

Univ. of Minnesota, oral ,commun., 1976).

d) General observed geometry of Mendocino triple junction,illustrating bending of San Andreas fault at itsnorthern end, rather than triple junction evolution,to maintain gross geometric stability.

K

sr ar SS~

KILCKCTERS

IOO

PIti~~a

0a

g /Vl/ x

0

+o

aa

0

~4'I

~

V o~+~ 0 y

eaee

V CEOKKTSICAL TRACK

0 OREOCC OR DART CCRC

CONTOUR INTERVAL SOOIICTCRS

~h, a,

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0,a

a

a

fea

So

I

0K<LOUET E RS

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l23~ 40' 22~ 39~ l2'8'7 l20'6'5~

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Franciscan ridge

Basin

Fault .

ptl,tt'0

CALASERA9 B'AV

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BASE4 ~ ~ OF ~ ~ ~ ~ ~CONTINENTAL '.."-"""LOPE

~ +

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40+ 39~ 38~ l25~ 37~ l24» 36~ 35 l23'4~ l22~

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-C-

X XX

TAULT, NACNUNCS OH OONNTHAOWM STOC

fAULT TONIC

AHTICLIAC 01 SASS@TNT 1ICCC

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fAULT ~ 0 f TAULT ~SAAI ANOACAS

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UOA ~, ~ SAIITA TOUT Igg

+ ~<11 S

0 IOO

55

4

P

55 It5'5 ITS 55 Ri Itt

t40 120 80 40 20 Km 0~ 0

Santo LuciaBank

Sonto ferro Basrn

C

./. KP

Sec L16

/ rr6aCZ

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k .~~~/r

20 Km 00

«c L18

20 Krn 00

s«L20

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20 Krn 00

/q 'r "=--. =;-'==--.=-~~.Q/ i ~ Sec

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07

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V,Kp 10K

~ ~

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Sec

Km 2 00

Sec L4

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~ r/ Cr ~

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Sec L6

20 Km 00

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20 Km 00

c'

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igf/r,rr

cS'r

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J-46

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O

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38'7

~

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38'-'

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70 .p(( ..oo ~ ~ "„".. Monterey

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rc~~c~ '-+yy38c

0 50 KM

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4@~~Ecrcrc

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35'24 c 123c 122c

35'21'-47

4 pe12S 123 ~

t

122'200400

I ~ ~

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'I I 0

(')

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V

MAGNETIC ANOMALY

I MEANS IOO nT (gommos)

CONTOUR INTERVAL:100 nT

INACTIVE TRARSFOIIM FAULT

BASK OF CONTINEtlTAL SLOPE

. UNCONTOURED tlAGNKTIC HIGH

MAJOR FAULTS

g, g~ ODCCA

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3.23

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l

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,ir'0'Km

~ ~ d ~\

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IO80 70 60 50

KILOMETERS40 20 IO 0

2000

300

3 CL-

OO1JJ

40

~ 0Stability Considerations of a FFT Triple Junction

0) Stable FFT 8} Unst'able FFT

Gorda

Pacific

America

Pl

lGW

PG

VelocityTriangle

Gorda

Pacific

, America )GAI

G

l

I

AlI

C) New Stability Conditionafter (D) RRR

AmericaPG

P

D} Mendocino FFTTriple Junction

GordaAmerica

yl'Pacific

PAA Pacific

PA means Paci fic- Anterica P l a te Boundar yplotted on velocity'riangle

J-55

~ ~~ ' ~

I ~

~ ~

~ ~

~ 4

~ ~

~ ~

~ ~App chica'".ion of Itnear s'Latts'Ltcal

mociels of ear&quake magnitucxeversus fault. Iengt>t tn esct!TlaLtng

rnaxImu~~ e;,pec'cable earthquaI:es

0~ ir

~ ~

r r~ Nrr'\r ~ ~

~ r~,'l

C ~~;1

r

Robert >x Marl'.S. Geological Surve

Menl, Park, California

940"';

ABSTRACT

Correlation or linear rcgrcssion estimates of earthquai;cmagnitude from data on liistorical magnitude and length of sur-'ace rupture should bc based upon the correct regression. I'orexample, thc regression of magnitude on thc logarithm of thclength of surface nipturc L can be used to estimate magnitude,but thc recession of log L on magnitude cannot. Rc~ccssiottcstimatcs arc most proliable values, and estimates of tnaximumvalues require consideration of onewided confidence limits.

lOOOC'OD

~ ~

~ ~

~ r r ~

'

INTRODUCHION

In estimating maximum expectable carthquakcs, it is commonpractice to assume a paximum length of surface rupture (typicallyonc-half the fault length) and use "lines of best fit" to cstimatcmaximuin magnitude front graphs comparing historical carth-quakc magnitudes and lcrgtlis of associated surface ruptiircs. Thisnote discusses thc intcrprctatinn and use of linear regression orcorrelation models for niaking statistical inferences from data

on'istoricalevents. Fnr cxamplc, DnniDa and Duchanan (1970) re-ported length of surface rupture L and Richter magnitude hf forthose earthquakes for svhieh these data v:erc available and prc-scntcd "best fit"equations of thc form lng L a+ bhf, that is,thc linear regressinns of log L nn magnitude (Fig. 1. linc AA').Othei authors (fnr exani pie, Tocher, 195S; lido, 1965) liavc calcu-lated rcgrcssinns of ma<!iiiludc nn log L (Fig. 1, lines DD'nd CC').

I will argue that all these rel!ressinn lines have bccn used ilt-corrcctly to cstiinate niaxinium earthquake magnitudes frommaximum ruplurclenglhs a.'nng foul!s. That is, th" v:rorg regres-sion linc (lng L on inagnitudc) has been used to cstimatc niagnitudcfrom niaximum rupture )englli, or regression estimates have beeninterpretetl as maximuin ralher then ninct likely mal!niluilcs (fnrcxaniplc, Greene anil nlhers, 1973; 5'entwnrth and nlhers, 1973;KYesson and nthers, 1974. 1975).

ce

CJ

C'>

I

r. io

>J

iO e8e> p

ct

a As ~ Ds 0 ec r 4

t:ARTHQV/AE use>r'>TUBE

1'igurc l. I.engih nf nt>se>ved sn>bee inpiuie in ictstiin> In esiih.quake n>a::nilude. l.ine *A is s iegiession line nf lng l. on >n.>dniin>.c.Lines till,CC', and till'ic>cpa ssi»n tines ur iuagniiude un t»gr J.. l.inAA'nd I)t)'ic based un ihe s»nc data.

K-1GCOLOGY, v. 6, p. dG4-4GG, AUGUST, t'ai

.rItW

A CORRELATION MODEL

Many models can be used to draw statistical inferences fromthc data on magnitude and lcng(h of rupture. A transformation tolog I. is used bccausc it tends to nornulizc thc data and to cn-hancc thc linear relationship. For thc purpose of this discussion, a

corrchtion model is postulated in which it is assumed that nmagnitude versus log L data points arc ranclocnly drawn from thepopulation of carthquakcs 1vith associated surface rupture andthat such a population has a bivariatc norcnal distribution (Fig. 2).As indicated b low. these assumptions arc morc rcstrictivc thannecessary. As shown in Figurc 2, thc rcgrcssion linc ol'on X, orY~ a + 1}X, passes through thc most probable value of Y foreach X and is thc appropriate linc to cstimatc Y given X. Theother regression linc, thc rcgrcssion ofX on Y, passes through thcmost probable value ofX for each Y and will not provide anunbiased estimate of Y given X. Thus. thc line of Bonilla andBuchanan (1970} in Figurc 1 is not the correct regression line forestimating earthquake magnitude from fault length. Itather, thcappropriate regression of magnitude on log L, calculated usingtheir strike-slip fault data, is liuc DD'Fig. 1). It is similar to thcequivalent regression lines of thc other authors.

ESTIV)ATIONOF MAXIMUMEARTHQUAYMMAGNITUDES

Thc regression lines of rnagnitudc on log L can bc used toestimate thc most likely rnagnitudc for a given maximum rupture.It must bc stressed that such an estimate is riot a maximum mag-nitude, but rather thc magnitude that could bc expected to beexceeded in 50% of thc earthquakes associated with that rupturelength.

x= ccrc gg

0 Px

It is possible to use thc statistical model to estimate thc mag-nitude, as a function of length, that could bc cxpccted to be cx-cccdcd in a given proportion (1 - cc} ofsurface-rupture occurrences.using a onc-sided confidence limit (IVonnacott and IVonnacott,1972, p. 280):

fcfrr,(L) = ilf(L)+ l t cx, s(log L -

la~7.)'I-+

I +5 (log Ll- logZ)~l~t

where M(L}is the rcgrcssion value, r,.o, is thc critical value of thcl distribution cvith (n - 2} degrees of frccdom, s is thc standarderror of thc rcgrcssion, Ll is thc rupture Icnl<h of thc ith carth-quakc occurrence in the sample of n earthquakes, and log L is thcmean of log L. That is, thc curve i'Vx(L) is thc locus of points suchthat for a particular L. I - cc is thc probability that the magni-tude will cxcced hQ. Note that the regression linc M(L) is equiva-lent to M,.,(L}.

As an cxamplc, Bonnilla and Buchanan (1970) reported dataon strike.slip faults (n ~ 20) and calculated the rcgrcssioa linc(L in mctrcs}

'og L ~ 1.915+ 0.389M, r ~ 0.70, s ~ Q.S2.

The regression of M on log L }acidsM ~ 1.235 + 1.2 13 log L. r ~ 0.70, s ~ 0.93.

These lines arc plotted in Figurc 3, along with tho data points.Also plotted arc the curves hf>.» and M, » lor thc regression ofM on log L..A magnitude value from the rcgrcssion linc 'f(L) canbc rcfcrred to as the most likely m..gnitude for a given rupturelength, and a value from hfJL) as a maximum cxpcctablc carth-quakc magnitude at cxcccd*nce probability' —cc.

Thc line EE'n Figurc 3 cocmects the points that form theright.side cnvelopc of the data. This field lies cntircly to the leftofMo», and on thc basis of thc model. there are potential cvcntslarger than EE'hat have probabilities in excess of 5%.

Thc prcccding numerical results are somewhat model dcpcnd-cnt, in that they dcpcnd on the population distribution and sscnpleselection, but thc genera) hnplications have wide application.Estimates of most likely earthquake magnitudes for a given valueof an "indcpcndent variable" (such as rupture length or faultdisplacement) must be based on thc correct rcgrcssion, and esti-mates of "maximum magnitude" rcquirc consideration of thedistribution about thc regression linc and thc application of onc-sidcd confidence limits.

These results can also bc derived from a less restrictive lineartcgrcssion model in which log L is treated as an independent vari-able and M is assumed to bc normally distributed about thcrcgrcssion li»e (Af on log L) with variance indcpcndcnt of L (Hays,1973, chap. IS). ll'he data warrant, thcsc models could be ex-panded to include additional "independent variables" such as

tectonic setting ancl hypoc.cntral depth. A statistical approach isalso nccdcd to csticnatc thc maximunt surlacc rupture (at somecxcccdance probability) for a given total fault length.

Flcclcc 2,'Yhc tcvo ccyccs)loll thws ic) 0 t)lvaliatc llocmat pop))tattoo,c contoc) cz indicate c teal pc))t at)ilitydensity, ~t)))tificd frocu 4'vc)c)acutt

and 4ocmacoct t t97)).''xcecdance pcobability is the probability that somcthi))t., in this

case mat.nitudc, v ctt t)c cxcccdcd.

GP.OLOGY

K-2

Q

I )30

h~

hs

Rrg

o

ls

v 4~4

Don)()a, hl. G., and Buchanan, J. I'l., 1970. Interim rcport on tvorld svidchistoric surface faulting: U.S. Geol. Survey Open File l(ep(., 32 p.

Grccnc, SV. H., I.ec, W.l).IL, hlcColloclh IL S., and Brabb, )L I „1973.I'aults and earthquakes in thc htontcrey Day region, California: U.S.Geol. Survey text tn accompany map MF 518, 14 p.

)lays, W. L., ) 973, Statis(ics for thc social scicncesr Ncsv York,)lolt.Rinehart, and Winctnn, 954 p.

lida, Numizi, 196S, I'.arthquakc magni(ude, earthquake fault and sourcedirncnsions: Nagnya Univ. Jour. Forth Sci., v. )3, p. I I 5~)32.

Tochcr, Don, 1958, Lsar(l>qua),"e energy and ground breakage( Seismol.Soc. America Bull., v. 48. p. 147-) 53.

Wcsson, R. L., I'agc, R. A., Boore, D. hl., and Yerkcs, R. I'., 1974, Isx.pcctable carthquakcs in thc Van No(roan Reservoirs area: U.S. Geol.Survey Circ. 69)-B, 9 p.

Wcsson, R. L., )le)Icy, E. J., La joie, K. R., and Wcnttvorth, C. M., 1975,Faults and future earthquakes, fn Irorcherdt. R. D., cd., Studies forseismic zonation of thc San Francisco flay region: U.S. Geol. SurveyProf. Paper 9C I-A, p. AS-A30.

Wenhvorth, C. h'l., Beni))a, M. G., and Buch nan, J. hl., 1973, Seismicenvironment of thc Burro Flats site, Ventura County. California(U.S Geol. Survry Open.File Rcpt.. 35 p.

Wonnacott, Thorn..s H., and Wonnacott, Ronald J., 19'12, introductorystatistics for business and economics: Ncsv York, Wiley, 622 p.

J(CIÃQAYLEDGMEHTS

Rcvicwcd by D. R. Dasvdy, D. G. Ilcrd, R. A. Page. and D. hl.Perl:ins.

hlANUSCRIPT RECEIVED APRIL 27, 1977

MANUSCRIPT ACCEPTED MAY 3, 1977

IA 3 q 85 C 66 07 8

KARTHQVAN\ s(AH(TVDE

Figurc 3. Length of obscrvcd surface rupturcvcrsus earthquakemagnitude for thc strike slip fault da(a of llunith and Ltuchanan (1970).Linc AA's thc regression linc ol'ng 1. on macnitude aml could be usedlo estimate thc ntost likely tuplurc length associated svith a given magni.tudc earthquake. I.inc IIps's the rctu essiun line of magnitude on log Iand c'ouid bc used to cstunate thc must likely earthquake tnagnitudeassociated with a riven lrngth of surface (upture. On thc basis oi'hccorrelation rnnA I, half thc car thqua'kcs associated with a given length ufsur(acc rup(ure rouhl bc eapcctcii (u lsc larger than IIIJ . The marnitudcs'given by linc Dl)'ou)J bc eapec(cd tn exceed 95%, of the a(agni(udes furearthquakes assucia(ed with a given I;ngth of surface (up(urc. Thc lincEE's the ri).ht.sh(c envelope of observed data.

K-3

~ WHlle IN vs a AUGUSi

ATTACHMENT L

UNITED STATES

DEPARTMENT OF THE INTERIOR

GEOLOGICAL SURVEY

REGRESSION ANALYSIS OF EARTHQUAKE MAGNITUDE AND SURFACE FAULT

LENGTH USING THE 1970 DATA OF BONILLA AND BUCHANAN

By R. K. Mark and M. G. Bonilla

Prepared in cooperation with U, S. Nuclear Regulatory Commission.

OPEN FILE REPORT 77-614

This report is preliminary andhas not been edited or reviewedfor conformity with GeologicalSurvey standards and nomenclature.

Menl o Park, Ca 1 ifor ni a

1977

REGRESSIOH ANALYSIS OF EARTH(UAKE MAGNITUDE AHD SURFACE FAULT

LENGTH, USING THE 1970 DATA OF BONILLA AND BUCHANAN

By R. K. Hark and t1. G. Bonilla

Introduction. The report of Bonilla and Buchanan (1970) includes re-

gressions of fault length on earthquake magnitude that can be used to

estimate most probable length of surface rupture given earthquake magni-

tude. Those regressions, however, have sometimes been incorrectly used

to estimate magnitude from fault length, as pointed out by Hark (1977).

Using the data of Bonilla and'Buchanan, this report gives regressions

of earthquake magnitude on length of surface rupture that can be correctly

used to estimate most probable magnitude if the length of surface rupture

is given. It also gives the regressions of length of rupture on magnitude

that can be used to estimate most probable length of rupture given earth-

quake magnitude.

In table 1 and figures 1-5 the numbering and lettering system used

to designate fault geography and fault types is the same as in Bonilla

and Buchanan (1970). Numbers 1-49 include surface ruptures that occurred

in North America and numbers 50-140 include ruptures outside of North

America. The fault types are indicated by letters as follows: A, normal-

slip faults; 8, reverse-slip faults; C, normal oblique-slip faults; 0,

reverse oblique-slip faults; and E, strike-slip faults.

Use of the re ression lines. The regression of log length on magnitude

L-2

~ ~(Log L=a+bM) can be us«d to estimate the most probable rupture length

given magnitude, and the regression of magnitude on log length (M=a+b

Log L) can be used to estimate the most probable magnitude given rupture

length. The estimation of 'maximum magnitudes'or a given rupture

length requires the use of one-sided confidence limits (Hark, 1977) .

References cited

Bonilla, H. G., and Buchanan, J. M., 1970, Interim report on world wide

historic surface faulting: U.S. Geol. Survey open-file rept.,32 p ~

Mark, R. K., 1977, Application of linear statistical models of earthquake

magnitude versus fault length in estimating maximum expectableY. Sq p + ~ + + 6 b~ AUQ 0 s l.earthquakes: Geology, +a-p~.'A

L-3

Table 1

Regression analysis of magnitude - surfac'e rupture length data from Bonilla andBuchanan (1970).

f

set

1-49

n r~

20 0.3?2

1-140 53 0.257

14 0.175

7 0.003

7 0.459

5 0.006

50-140 33 0.217

10. 64.

8. 57.

Log(L)=a+b~H

a b

-0. 91 0. 35

-1.49 0.40

2.55

0.01

4.24

0.02

-0.69 0.28

not significant

-2.81 0.61

not significant

17.62 -0.96 0.34

N=a+b*Log(L)

b

1.08

0.54

0.76

0.63

0.90

0.64

0.80

0.68

0.38 6.08 0.75 0.42

s a

0.51'.230.55 6.56

0.53 6.03

0.45 6.19

-E

A+C 21 0.279 7.37 -1.46 0.40

20 0.484. 16.87 -1.08 0.39 0.52 4.96

0.45 6.13

1.24 0.93

0.70 0.59

B+D

C+D+E

12 0.033 0.34

32 0.367 17.42 -1.24 0.40

not significant

0.55 5.62 0. 93 0 84

12 0.'230 2.99 -2.79 0.59 0.57 6.62 0.39 0.47

B+E 27 0.299 10.65 -0. 71 0. 32 0.56 5.71 0.94 0.97

A+C+E 41 0.380 23.94 -1.20 0.39 0.49 5.56 0.99 0:79

B~D+E 32 0.251 10.07 -0.81 0.32 0.60 5.98 0.78 0.93

Notes

"n" is the number of cases.

"t " is the fraction of the variance explained by the regression. It ranges from 0(no linear relationship) to 1 (perfect linear relationship)."f" is a measure of statistical significance of the regression and is equal to r~/.((1-8 )(n-2))."L" is in kilometers.

"s" is the standard error of the estimate. s~ is equal to the residual sum of squareerrors about the regression line divided by the degrees of freedom (i.e., n-.2).

L-4

SICKO,

800'00600

50Q

400

500

20Q0

KELJ

IOO

0 90

hC8070I-6oD

u. 50

40

soDI-

20

SORLDV/!DE DATA

0

O

b. IO0 9

8

7Rld 6

5

O

0X

0/tp

0

hO+

OEO

I/

O0

5 t

EARTH'QUAKF MAGNITUOEL-5

9

F ip.l

IOOO800eOO

700

600

500

400

300

200

M

LIJI-IOO

0 9080

hC70

60

50

NORTH AMERICAN DATA

40«K

QJ 30IL

I-LL.

20KLalO

IoLL. 9O

8

I- 7

Z 6LLJ

'''V~

o~

OaO

O

4Q

6EARTKQUAKE MAGNITUDE

L-6

7' 9Fig.2

9oo~ '( ~

800700

600

500

400

500

200

V)CLLal

le loo0 90

8070I-Go

50

NORMAL-SLli~ FAULT DATA

40Z

soKI-tL

20

u-, lo0 9

8

7R6

5

0'

0X

CnO

0+

Cb

5 6

EARTHQUAKE MAGNITUDE

L-7 /)

IOOOeno800700

600

500

400

500

200

VlfLldI-

ion0 90

8070

I~ 60

U 50

R40

lL soDI-0

20

ORBAL OBLIQ UE-SLt P FAULT DATA

O

KD

lo0 9

I- 8

LU

5

0

O

h

O+

DCO

II

5 6EARTHQUAKE MAGNITUDE

L-8

.aoo000700

600

500

400

300

200

CO

LLII-

O

bC

LL.

IOO

908070

60

50

STPiI ViE-SLIP FAULT DATA

cf

LLJ

I-tLD

LLjCD

tO

LL

OxI-E9zLLJ

40

30

20

lo

8

7

6

5

0

o'.

/j

ChO

0)

5 6

EARTHQUAKE MAGNITUDE

~ g '~

I

NAME James N. Brune

ATTACHMENT M

BIRTHDATE (MO., DAY, YR.)

November 23, 1934

BIOGRAPHICAL SKETCH(PROVIDE FOLLOWING INFORh)ATION FOR ALL PROFESSION~RSONNELENGAG~ TIIE PROJECT, BEGINNING WITH THE PRINCIPAL ~TIGATOR.)

PLACE OF B(RTH(CITY, STATE, COUNTRY)

Modesto, California U.S.A.

PRESENT NATIONALITY(ALIENS INDICATE KINO OF VISA AND EXPIRATION DATE)

U.S. Citizen

EDUCATION (BEGIN WITH BACCALAUREATE TRAINING AND INCLUDE POSTDOCTORAL)

DEGREE

B.Sc.

Ph.D.

YEAR CONFERRED

1956

1961

INSTITUTION AND LOCATION

University of Nevada, Reno, Nevada

Columbia University, New York City

HONORS AND AWARDS

See Attached

MAJOR RESEARCH INTEREST

Earthquake Source MechanismTectonicsEarth Structure

RESEARCH AND/OR PROFESSIONAL EXPERIENCE (STARTING WITH PRESENT POSITION, LIST PROFESSIONAL BACKGROUNDAND Eh'IPLOYMENT)

Professor oI Geophysics-University of California, San'Diego, 1969-Associate Director, Institute of Geophysics and Planetary Physics, University of

California, San Diego, 1973 — 1976..Chairman, Geological Research Division, Scripps Institution of Oceanography,

University of California, San Diego, 1974 - 1976.Associate Professor of Geophysics-California Institute of Technology, 1965 - 1969.Adjunct Associate Professor of Geology-Columbia University, 1964.Geophysicist, U. S. Coast and Geodetic Survey, 1964.Research Scientist, Columbia University, 1958 - 1963.

'xplorationResearch, Chevron Oil Company, 1957.Exploration Geophysics, Chevron Oil Company, 1956.

UCSD-0071

James N. Brune

.HONORS

Higgins Fellowship, Columbia University, 1956University Fellowship in Geophysics, Columbia University, 1957-58i)ax Fleischr~~an Scholarship, University of Nevada, 1954-55Jones-Hoover Scholarship, University of Nevada, one yearJ. B. HacIlwane Award of American Geophysical Union, 1962Fellow of the American Geophysical Union, 1967Grove Karl Gilbert Award in Seismic Geology, 1967Seismol'ogical Society of America: Board of Directors, 1967-present,

Yice-President, 1969, President, 1971Meri>ber of New York Acaderi>y of Sciences, 1970Arthur L. Day Award, 1972G.. K. Gilbert Award, Carnegie Institution of Washington, 1967Llstlngs in vho s vho in the vest, kne2ican Zen of science

M-2

BIBLIOGRAPHY

James N. Brune

l.

2 ~

(With J. Oliver) The Seismic Noise of the Earth's Surface, Bull. Seism.Soc. Amez., 49: 4, 349-353 (1959).

(With J. E. Nafe and J. E. Oliver) A Simplified Method for the Analysisand Synthesis of Dispersed Have Trains, Jour. Geophys. Res., 65: 1, 287-304(1960).

3 ~ (With J. E. Nafe) Observations of Phase Velocity for Rayleigh Waves in thePeriod Range 100 to 400 Seconds, Bull. Seism. Soc. Amer., 50: 3, 427-439(1960).

4 ~ Radiation Pattern of Rayleigh Waves from the Southeast Alaska Earthquake of10 July 1958, Domin. Observ., 24, 20, A Symposium on Earthquake Mechanism,1-11 (1961).

5.

6.

7.

8.

(With M. Ewing and J. Kuo) Group and Phase Velocities for Rayleigh Wavesof Period Greater than 380 Seconds, Science, 133: 757 (1961).

(With J. E. Nafe and L. E. Alsop) The Polar Phase Shift of Surface Waveson a Sphere, BuZZ. Seism. Soc. Amer., 51: 247-257 (1961).

(With H. Benioff and M. Ewing) Long-period Surface Waves from the ChileanEarthquake of May 22, 1960, Recorded on Linear Strain Seismographs,Jouz.. Geophys. Res., 66: 9, 2895-2910 (1961).

Attenuation of Dispersed Wave Trains, BuZZ. Seism. Soc. Amer., 52:1, 109-112 (1962).

9.

10.

11.

12.

13.

14.

(With J. T. Kuo and M. Major) Rayleigh Wave Dispersion in the PacificOcean for the Period Range 20 to 140 Seconds, Bull. Seism. Soc. Amez'., 52:27 333-357 (1962).

Correction of Initial Phase Measurements for 'the Southeast Alaska Earthquakeof July 10, 1958, and for Certain Nuclear Explosions, Jouz. Geophys. Res.,67: 9, 3643-3644 (1962).

(With M. Ewing and J. Kuo) Surface Wave Studies of the Pacific Crust andMantle, Geog. Monograph, 6, Crust of the Pacific Basin, (1962).

(With J. Dorman) Seismic Waves and Earth Structure in the Canadian Shield,Bull. Seism. Soc. Amez., 53: 1, 167-209 (1963).

(With A. Espinosa and J. Oliver) Relative Excitation of Surface Haves byEarthquakes and Underground Explosions in the California-Nevada Region,Jour. Geophys. Bes., 68: ll, 3501-3513 (1963).

Use of Surface Have Rejection Filters to Record Mantle Haves of Low Order, "~-Earthquake iVotes, 34: 73 (September — December 1963). (Abstract)

M-3

N. Brune — Bibliog hy

~~

(With P. E/. Pomeroy) Surface Wave Radiation Patter'ns for UndergroundNuclear Explosions and Small Magnitude Earthquakes, Jour. Geophys. Res.,68: 17, 5005-5028 (1963).

Travel Times, Body Waves, and'Normal Modes of the Earth, Bull. Seism. Soc.Amer., 54: 6, 2099-2128 (1964).

(With R. Chander) Radiation Pattern of Mantle Rayleigh Waves and theSource Mechanism of the Hindu Kush Earthquake of July 6, 1962, Bull. Seism.Soc. Amer., 55: 5, 805-819 (1965).

(With L. E. Alsop) Observations of Free Oscillations Excited by a DeepEarthquake, Jour. Geophys. Res., 70: 24, 6165-6174 (1965).

The Sa Phase from the Hindu Kush Earthquake of July 6, 1962, Pure andApplied Physics, 62: 3, 81-95 (1965).

P and S Wave Travel Times and Spheroidal Normal Modes of a HomogeneousSphere, Jour. Geophys. Res., 71: 12, 2959-2965 (1966).

(With J. Oliver, A. Ryall and D. Slemmons) Micro-earthquake ActivityRecorded by Portable Seismographs of High Sensitivity, Bull. Geol. Soc.of Amer., 56: 4, 899-924 (1966).

(With R. C. Liebermann, C. Y. King and P. W. Pomeroy) Excitation ofSurface Waves by 'the Underground Nuclear Explosion Long Shot, Jour. Geophys.Res., 71: 18, 4333-4339 (1966).

F

(With C. R. Allen) A Micro-earthquake Survey of the San Andreas Fault Systemin Southern California., Bull,. Seism. Soc. Amer., 57: 2, 277-296 (1967).

(With C. R. Allen) A Low-stress-drop, Low-magnitude Earthquake with SurfaceFaulting: The Imperial, California, Earthquake of March 4, 1966, Bull. Seism.Soc. Amer., 57: 3, 501-514 (1967).

(With M. Wyss) The Alaska Earthquake of 28 March 1964: A Complex HultipleRupture, Bull. Seism. Soc. Amer., 57: 5, 1017-1023 (1967).

(With C: Y. King) Excitation of Mantle Rayleigh Waves of Period 100 Secondsas a Function of Magnitude, BulZ. Seism. Soc. Amer., 57: 6, 1355-1365 (1967).

She FauR'Slips, Engineering and Science Magazine, California Institute ofTechnology, 31: 2, 36-38 (1967).

Seismic Moment, Seismicity, and Rate of Slip along Major Fault Zones, Jour.Geophys. Res., 73: 2, 777-784 (1968).

M-4

~ E ~

ii

James N. Brune - Bibliography

28. Source Dimensions of Earthquakes and Underground Explosions of MagnitudeNear 4.0, Earthquake Notes, p.'22, (Abstract), June, 1969.

29. (Mith C. R. Allen, A. Grantz, M. M. Clark, R. V. Sharp, T, G. Theodore,E. M. Wolf and H. Myss), The Borrego Hountain, California, Earthquake ofApril 9, 1968: A Preliminary Report, Bull. Seism. Soc. Amer., 58: 3,1183-1186 (1968).

30. (With H. Myss), Seismic Homent, Stress and Source Dimensions for Earthquakesin the California-Nevada Region, Jour. Geophys. Res., 73: 14, 4681-4694 (1968).

31. Regional Variations in the Structure of the Upper Mantle and the Propagationof the Sa Phase, Continental Margins and island Arcs, Upper Mantle ComiitteeSymposium, Ottaua, Canada, -'965, GSC Paper 66-15, (1969).

32. Surface Maves and Crustal Structure, Geophysical rVonograph, 13: 230-242 (1969).

33 (With G. R. Engen), Excitation of Mantle Love Waves and Definition of YiantleWave Magnitude, Bull. Seism. Soc. Amer., 59: 2, 923-933 (1969).

33a.

34.

35.

Seismicity, Rate of Slip, Stress and Heat Flow along the San Andreas Faultin California, EOS Trans. Amer. Geophys. Union, SO: 5, May 1969.

(With'T, Henyey and R. Roy), Heat, Flow, Stress and Rave of Slip Along theSan Andreas Fault, California, Jour. Geophys. Res., 74: 15, 3821-3827 (1969).

I E

(With M. Thatcher), Higher Mode interference and Observed Anomalous Appa entLove Wave Phase Velocities, Jour. Geophys. Res., 74: 27, 6603-6611 (1969).

36. (With H. Trifunac), Complexity of Energy Release During the 1'mperial Valley,California, Earthquake of 1940, Bull. Seism. Soc. Amer., 60: 1, 137-160 (1970).

37 ~

38.

(With D. Anderson, C. Archambeau, C. Richter, S. Smith), Earthquakes andNuclear Detonations, Science, 167: 1011-1012 (Feb. 13, 1970).

(With W. Arbasz and G. Engen), Locations of Small Earthquakes Near theTrifurcation of the San Jacinto Fault Southeast of Anza, California, Bull.Seism. Soc. Amer., 60: 2, 617-627 (1970).

39. Tectonic Stress and the Spectra of Seismic Shear Waves from Earthquakes,Jour. Geophys. Res., 75: 26, 4997-5009 (1970).

40. Seismic Sources, Fault Plane Studies and Tectonics, EOS, 52: 5, 178-187,Hay 1971, (IUGG Quadrennial Report'n Seismology for U.S.)

:ames N. Brune - Bibliography PD I'a'V

«2 ~

3 ~

(with flayne Thatcher) "Seismic Study of an Oceanic Ridge Earthquake.Swarm in the Gulf of California'eophps. Z. p. as0z'. Soc.,22: 473-489 (July, 1971).

(with Cinna Lomnitz, F. Hooser, C. P.. Allen, and W. Thatcher)"Seismicity and tectonics of the northern Gulf of CaliforniaRegion, Hexico. Preliminary Results. Gee]'isica InternacionaZ, ~ 0:37-48, Hexico, 1970.

"Seismic Methods for Monitoring Underground Nuclear Explosions,an Assessment of the Status and Outlook", (Book Review) InternationalInstitute for Peace and Conflict Research (SIPRI) Stockholm, Sweden,BuZZ. Seism. Soc. Ames'.

f ~ (with W. Prothero, J. Dratler, B. Block) "Surface Wave Detection witha Broad-Band Accelerometer", l'/atua, 23Z:,21, 80-81 (Hay, 1971).

(with J. Davies) "Regional and Global Fault Slip Rates from Seismicity",Ei1ature, 229, 101-107 (January, 1971).

"Seismic Discrimination Between Earthquakes and Underground Exolosions",statement and testimony at Hearings before Subcommittee on Arms Con rol,International Law and Organization, Ninety-second Congress of the U.S.,First Session on Comprehensive Nuclear Test Ban Treaty, 139-149 (July22-23, 1971).

r p ~ (with Hax Wyss) "Regional Variations of Source Properties in SouthernCalifornia Estimated from the Ratio of Short-to Long-Period Amplitudes",Bull. Seism. Soc. Amer., 6Z,1153-1167 (October, 1971).

"A Deployment Program for Seismic Monitoring of a Comprehensive Test BanTreaty", statement and testimony at Hearings before Subcommittee on Research,Development, and Radiation of the Joint Committee on Atomic Energy Congressof the U.S., Ninety-Second congress, First Session on Extent of PresentCapabilities for Detecting and Determining Nature of Underground Events,133-142 (October 27-28, 1971).

~ ~r ~ (with W. Prothero) "A Suitcase Seismic Recording System", BulZ. Seism.Scc. Amez'., 6Z, 6, 1849-1852 (December, 1971).

4 ~

(with D. McKenzie) "Melting on Fault Planes During Large Earthquakes",Gecpnus. J.B. as'. Soc, 29:1"(.1972).

(with D. Oldenburg) "Ridge Transform Fault Spreading Pattern in FreezingWax, Science, Vol. 178 (1972) 301.

M-6

52. C. R. Allen, M. Myss, J. N. Brune, A. Grantz and R. E. Wallace."Displaccments on the Imperial, Superstition Hills, and San Andreas FaultsTriggered by the Borrego Mountain Eartnquake". In U.S.G.S., Prof. Paper8787, pp. 87-104 (L972 ),

53.

t

54.

B. E. Tucker and J. N. Brune.. "Seismograms, S-Wave Spectra and SourceParameters for Aftershocks of the San Fernando Earthquake of February 9,1971." I/OAA Special Report, 1973,

I. Reid, M. Reichle, J. Brune and H. Bradner. "Microearthquake Studiesusing Sonobuoys: Preliminary Results from the Gulf of California."Geophys. J'. B. astr. Soc., 34, 365-379 (1973).

55, J. N. Brune, S. de la Cruz, H. Bradner, C. Villegas, I. Reid, M. Reichle,'A. Nava, M. Lozada and P. Silva. "Earthquakes in the Gulf of CaliforniaRecorded using Land-Based Recordings of Moored Hyd.ophone Arrays."Geofisica Zrit., 12 (3), 201-212 (L972 ).

56. J. N. Brune and C. Lomnitz. "Recent Seismological Developments Relatingto Earthquake Hazard." Geofisica Znt., 14: pp. 49-63 (1974),

"57. P. Molnar, B. E. Tucker and J. N. Brune. "Corner Frequencies of' and S Haves8 Models 'oE Earthqu'ake Sources,"'ull. Seismo. Soc. i'., 63, 2091-2105 (1973).

58.

59.

F. Gilbert, A. Dziewonski and J. Brune. "An Informative Solution to aSeismological Inverse .roblem". Proc. Efat 'l. Acad. Sci., 70, 5, pp. 1410 ( 1973.).

W. Thatcher and J. N. Brune. " Surface waves and crustal structure 'n theGulf of Californ'ia region." Bull. Seism. Soc. Am, 63, 5, 1689-3.698 (1973).

60. Brune, J. N. "Earthquake modelling by stick-slip along pre-cut surfacesin stressed foam rubber". Bull. Seism. Soc. Am., 63,.~. 6., 2105-2119.

( 197,3).

61.

62.

63.

64.

65.

Brune, J. N. and F. Gilbert, "Torsional Overtone Dispersion from Correla-tions of S Waves to SS Waves", Bull. Seiam. Soc. Am., 64 (2), 313-320-(1974).

H. Bradner and J. Brune, "The Use of Sonobuoys in Determining Hypocentersof Aftershocks of the February 21,. 1973 Pt. Mugu Earthquake," ~l.l,.Am., 64, No..l, 99-101, 1974.

J. N. Brune, "Current Status of.Understanding Quasi-Permanent FieldsAssociated with Earthquakes",'EOS, 55, No. 9, 1974.

t

D. M. Oldenburg and J. N. Brune, "An Explanation for the Orthogonalityof Ocean Ridge" and .Transform Faults", J. Geophys. Res., 80, no. 17,.p. 2575, 1975.

Alfonso Reyes, J. Brune, L. Canalcs, J, Madrid, J, Rebollar, L. Munguia,T. Barker, "A Microearthquake Survey of the San Miguel Fault, Baja California,Mexico",Geophys, Res. Lttrs p 2) 56 59 3975.

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James N. Bruno - B'ography Page1

~a

66, James Brune, Cinna Lomnitz, Clarence Allen, Fredorico Hooser, Francis I ohnor,~ and Alfonso Reyes,"A Permanent Seismograph Array Around the Gulf ofCalifornia," Z~li'. Soi.one. 8o'~. Am., 66, 969-978, 1976.

67. Ralph Archuleta and James N. Brune, "Surface Strong Motion Assoc-atedwith a Stick-Slip Event in a Foam Rubber Model of Earthquakes " Bull,Soismo. Soc. Am., 65, 1459-1071, 1975.

68.

69.

70.

Brian E; Tucker and J. N..Brune, "Source Hechanism and Surface-wave—Excitation for Aftershocks of the San, Fernando Earthquake", Geophys.J. R, astr, Soc,, 49 37>~426) >977r.

Hichaol Reichle, George Sharman, and James Brune,"Sonobuoy and TeleseismicStudy of Two Gulf of California Transform Fault Earthquake Sequences",Bull. Seisrrio. Soc. Amer., 66, 1623-1642, 1976.

'illiam A'. Prothero., Ian Reid, Michael Reichle, James Brune, 'Ocean -BottomSeismic Measurements on the East Pacific Rise and Rivera Fracture Zone",Nature, 262, 121-124, 1976.

71. George F. Sharmanr Michael Sr Reichle> James. N, Brune, "A Detailed Studyof Relative Plate Hotion in the Gulf of California," Geology, April; pp.206-210$ 1976.

II

72. Stephen H. Hartzell and James N. Brune, "Source Parameters for theJanuary> 1975 Brawley — Imperial Valley Earthquake Swarm" PAGEOPH, 1151977.

73. James N. Brune, Alfonso Reyes, Michael S. Reichle, "Recent Seismic and'Tectonic Studies of the Gulf of California", CIBCASIO Annual Report, 1976.

74.

75.

.76.

James N. Brune, R. Archuleta, J. Frazier, G. Hegemier, "Physical andNumerical Modeling of Spontaneous Slip", sugary of talk given atNorthwestern University at NSF Workshop on "Application of ElasticWaves in Electrical Devices, Non-Destructive Testing and Seismology"Hay 24-26, 1976.

1

James N. Brune,"Q of Shear Waves Estimated from S - SS SpectralRatios," Geophys. Res. Lttrs., 4, No. 5, 1977.

Stephen.H. Hartzell, Gerald A. Frazier and James N. Brune, Earthquakemodeling in a homogeneous half=space,r'ull. Seism. Soc. A'm., 68, 301-316, '978.

77. Keith Priestley and James N. Brune, "Surface Waves and the Structureof the Great Basin of Nevada and Western Utah", accepted for publi-cation, 1977.

78. Luis Munguia, M, Reichle, A. Reyes, R. Simons, J. N. Brune, "Aftershocksof the 8 July 1975 Canal De Las Ballenas, Gulf of California, Earthquake",Geaphysical'es. Lttr .', 4, No. 11, 1977.

M-8:

79, J. N. Brune, "implications of Earthquake Triggering and Rupture Propa-gation for earthquake Prediction Based on Premonitory Phenomena",presented at USGS Conference on Fault Mechanics and its Relation toEarthquake Prediction, December 1-3, 1977.

80. J. N. Brune, R. J. Archuleta and S. H. Hartzell, "Far-Field S-WaveSpectra, Corner E'requencies and Pulse Shapes", presented at

USGS'onferenceon Fault Mechanics and its Relation to Earthquake PredictionDecember 1-3, 1977..

81. Stephen Hartzell, James N. Brune and Jorge Prince, "The October 6, 1974Acapulco E'arthquake and the importance of Short Period Surface Waves inStrong Ground i~fotion, in preparation, 1978.

82. James N. Brune, "Statement to the ACRS" meet f h S bmeeting o t e Subcommitteeof the Advisory Committee on Reactor Safeguards, Los Angeles Califos, a ornia,

83. Stephen Hartzell and James N. Brune, "Analysis of the Bucharest StrongGround Motion Record for the March 4, 1977 Romanian Earthquake", inpreparation, 1978.

84. A. Reyes, J. N. Brune and C. Lomnitz, "Source Mechanism and AftershockStudy of the Colima, Mexico Earthquake of January 10, 1973", in pre-paration, 1978.

85. Stephen Hartzell and James N. Brune; "The Horse Canyon Earthcuake ofAugust 2, 1975 — Two Stage Stress Release Process in a Strike-SlipEarthquake", in preparation, 1978.

M-9

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ATTA IEI<T N

Curxiculum Vitae for J. Enrique Luco

Birth Date: May 18, 1943 - Vina del Mar, Chile

Education:

W

Scientific Research:

Ph. D. University of California, Los Angeles - 1969.Civil Engineer, University of Chile, Santiago - 1967.

Includes studies on the effects of geology and localsite conditions on earthquake ground motion;dynamxc response o~ zoundaticns; "oil-str"ct ~ rcinteraction during earthquakes; wave propagationon a simplified model of the Earth; evaluation ofearthquake damage; earthquake response of nuclearpower plants; forced vibxations ofstructures.

Employment; Associate Professor of Applied Mechanics, Universityof California, San Diego, 1977«present.

Assistant Professor of Applied Mechanics, Universityof California, San Diego, 1974-1977.

Senior Research Fellow in Applied Science, CaliforniaInstitute of Technology,'973-1974.

Researcher, Department of Geophysics, University ofChile, 1970-1973.

Professor in the Departments of Mathematics andPhysics, University of Chile, 1971-1972.

Research Fellow in Applied Sciences, CaliforniaInstitute of Technology, 1970.

Research Assistant, Department of Geophysics,Unive rsity of Chile, 1965- 1967.

ProfessionalSocieties

Membership: American Society of Civil Engineers.Seismo)ogical Society of America.Am'erican Academy of Mechanics.Sigma Xl,

Publications of J. E. 'Luco

l. 1967. Pro a ation of Hi h-Fre uenc Com ressional Pulses in a La eredSphere, Civil L'ngincer Thesis, Facetted de Ciencias Fisicas yMatematicas, Universidad de Chile, Santiago, Chile (PublicationNo. 45, Department of Geophysics, University of Chile, Santiago).

2. 1969. "Dynamic Interaction of a Shear Wall with the Soil," J. EngineeringMechs. Div., ASCE, Vol. 95, No. EM2, April, pp. 333-346..

3. 1969. A lication of Singular Inte ral E uations to the Problem of ForcedVibrations of a Ri id Foundation, Ph. D. Dissertation, School ofEngineering and Applied Science, University of California, Los Angeles.(December).

~ 4. 1970. "Dynamic Soil-Structure Interaction," with Hradilek, P. J., InformeTecnico No. 14 Instituto de Investigaciones Ensa es de Materiales(IDIEM), Universidad de Chile, Santiago, Chile.

5. 1970. "Strong Earthquake Motion and Site Conditions: Hollywood, " withDuke, C. M., Carriveau, A. R., Hradilek, P. J., Lastrico, R.,and Pstrom, D., Bull. Seisme Soc. Amer., Vol. 60, No. 4,August, pp'. 1271-1289.

6. 1971. "Dynamic Response of Circular Footings," with Westmann, R. A.,Engineering Report No. 7113, School of Engineering and AppliedScience, University of California, Los Angeles (April).

7.'971. "Dynamic Response of Circular Footings," with Westmann, R. A.,J. En ineerin Mechs. Div., ASCE, Vol. 97, No. EM5, October,pp. 1381-1395.

8. 1971. "Informe Preliminar, sobre Intensidades y Danos causados por elSismo de 8 de Julio de 1971: Zona Calera - Illapel," with Lastrico,R., and Medone, C. A., Revista Geografica, de Chile, No. 21, pp.14-19, Santiago, Chile.

9. 1972. "A Preliminary Report, The July 8, 1971 Chilean Earthquake, " withEisenberg, A., and Husid, R., Bull. Seisme Soc. Amer., Vol. 62,No. 1, February, pp. 423-430.

10, 1972. Dynamic Response of a Rigid Footing Bonded to an Elastic Half-Space," with Westmann, R. A., J. A l. Mech., ASME, Vol. 39,Series E, No. 2, June, pp. 527-534.

N-2

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ll, .1972. "El Terremoto de San Fernando en California," with Lastrico, R.,Revista de la Construccion, Ano XI, No. 117, Junio-Julio, Santiago,Chile.

12. 1972.r r ~ ~

r r"Ingenieria Sismica en Chile: una Bibliografia, " Informe TecnicoNo. 15, Instituto de Investigaciones Ensa es de Materiales(IDIEM), Universidad de Chile, Santiago, Chile.

13. 1973. "Dynamic Structure-Soil-Structure Interaction," with Contesse, L.,Bull. Seism. Soc. Amer., Vol. 63, No. 4, August, pp. 1289-1303.

14. 1973. "Vibraciones Horizontales de un Disco Rigido sobre un SemiespacioElastico," Revista del Instituto de Investizaciones Ensaves deMateriales (IDIEM), Vol. 12, No. 1, pp. 1-13, Universidad deChile, Santiago, Chile.

15. 1974. "Soil-Structure Interaction - Continuum or Finite Element", "withTsai, N. C. and Hadjian, A. H., Nuclear En~ineerin and Design,Vol. 31, No. 2, pp. 151-167.

16, 1974. "The Dynamic Modeling of the Half Plane by Finite Elements," withBos, H., and Hadjian, A. H., Nuclear En ineering and Design,Vol. 31, No. 2, pp. 184-194.

17. 1974. "Two-Dimensional Approximations to the Three-Dimensional Soil-Structure Interaction Problem," with Hadjian, A. H., NuclearEn ineerin and Desi, Vol. 31, No. 2, pp. 195-203,

18. 1974. "Impedance Functions for a Rigid Foundation on a Layered Medium,"Nuclear En ineerine and Design, Vol. 31, No. 2, pp. 204-217,

19. 1975. "Full Scale, Three DiiYlensio.al Tes o Str ct r 1 De ormationsDuring Forced Excitation of a Nine-Story Reinforced ConcreteBuilding," with Foutch, D. A., Tzifunac, M. D., and Udwadia,F. E., Procecdin s U.S. Nation" 1 Conference on Earthquake

9

20. 1975. "An Experimental Study of Ground Deformations Caused by SoilStructure Interaction," with Trifunac, M. D., and Udwadia, F. E.,Proceedings U.S. National Conference on Earth uake En~ineerinJune, 1975, Ann Arbor.

21. 1975. "A Note on the Dynamic Response of Rigid Embedded Foundations,"with %'ong, H. L., and Trifunac, M. D., Earthquake Engineeringand Structural Dynamics, Vol. 4, No. 2, pp, 119-128.

22. 1975. "Dynamic Modeling of a Viscoelastic Half-Space by Finite Elements,"with Hadjian, A. H. and Atalik, S., Proceedings Second ASCEConference on Structural Desi n of Nuclear Plant Facilities,December, 1975, New Orleans.

23. 1976. "Torsional Response of Structures to Obliquely Incident SHWaves," Earth uake En ineering and Structural namics,Vol. 4, No. 3, January-March, pp. 207-219.

24. 1976. "Torsional Response of Structures for SH-Waves: the Case ofHemispherical Foundations," Bull. Seism. Soc. Amer., Vol.66, No. 1, February,,pp. 190-123.

25. 1976. ",Vibrations of a Rigid'Disc on a Layered Viscoelastic Medium,"Nuclear En ineering and Desi n, Vol. 36, No. 3, March, pp.325-340.

26. 1976. "Torsion of a Rigid Cylinder Embedded in an Elastic Half-Space," Journal of Ap lied Mechanics, Vol. 43, Series E, No. 3,September, pp. 419-423.

27. 1976. "Dynamic Response of Rigid Foundations of Arbitrary Shape,"with Wong, H. L., Earth I ake Engineering and Structural

6, *- *.. 9-9

28, 1976. "Torsional Response of a Rigid Embedded Foundation," withApsel, R. J., J. of the En@re. Mech. Dives ASCE, Vol. 102,No. EM6, December, pp. 957-970.

29. 1977. "Dynamic Response of Rectangular Foundations for RayleighWave Excitation," with Wong, H. L., Proceedings of theSixth World Conference on Earth uake Engineering, New Delhi,India.

30, 1977. "On the Importance of Layering on the Impedance Functions," withHadjian, A. 'H., Proceedings of the Sixth World Conference onEarth uake Engineerin, New Delhi, India.

31. 1977. "Contact Stresses and Ground Motion Generated by Soil-StructureInteraction," with Wong, H. L. and M. D. Trifunac, EarthqualceEn ineerinz and Structural namics, Vol. 5, No. 1, January-March, pp. 67-69.

32. 1977. "The Application of Standard Finite Element Programs in the'Analysis of Soil-Structure Interaction, 99 with Wong, H. L., Proc.of the Second SAP User's Conference, Umversit of SouthernCalifornia, June 1977, Los Angeles.

~ ~

l ~ E I ~I

33. 1977.

34. 1978.

"Seismic Response of a Periodic Array of Structures," withMurakami, H., Z. of the Engrg, Mechs. Div., ASCE, Vol. ~103

No. EM5, Oct. > pp. 96~-977.r

"Dynamic Response of Rectangular Foundations to Obliquely"it

En ineerin and Structural D amies, Vol. 6, Zan., pp. 3-16.

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ATT NEHT 0

CURRICULUM.VITAE FOR iVIIHAILOD. TRIFUNAC

Birth Date:ggG ] 7 578

7 November 1942K'kinda, Yugoslavia

Ed" ca on:

Pn. D. Califor .i Inst'tute of Te" hnology, Civil Enginee" ing andGeophysics, 1969

M. S. Princeton. University, Civil Engineering, 1966B. S. University of Belgr-de, Civil Engineering, 1965

Scientific Research:

Includes investiga ion of strong earthquake ground. motionsfollowing Parkfield, California, 1966 earthquake (1967+); high-frequency resolution and strong-motion mechanism study ofImperial Valley, California 19-"0 earthquake (1968+); siznplemathematical models of an alluvial valley subject to strongearthquake motion (1968+); ambient and forced vibration studiesof several multi-story structures (1968+); laboratory evaluation

'nd,instrument correction methods of strong motion accelerogzaphs()970+); development of the data processing methods of strong-motion accelerograms (1970+); s atistics and triggering mech" nismof earthquakes (1968+); studies of microtremor vibrationsthe Imperial Valley (1970+); study of net methods for synthesizingartificial strong ground zwotion (1970+); invest gation of the soil-structure interaction (1970+); amplification and. focusing effectsin complicated geologic structures (1971+); stress estimates and .

source mechanism studies of earthquakes based, on the recordedstrong -motion ace elex ograms (1971); development of seismicdesign criteria. in terms of respozise spectra (1975+); developr .entof approximate scaling methods foz strong earthquake groundmot on in terms of peak accelerations, velocities and displa'ements(1975+); studies on duration of strong ea thquake ground mot'on(1974+); soil-bridge-soil interaction'roblems (1975+); soil-structure-soil.-structure interaction problezns (1975+).

~l~ ~

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pro>c:nOv C~g gg,L gbpillCC Ip ) Qp$ J0p+p g g~ Qp(.JJQ)Q ~/Oft(l ' '( I (0ssistant Professor of Applied S'cience, Calif'ornia Institute of

Technology, 1972- l'l')~Research Associate, Lamo..t-Doherty Geological Observatory and

Lecturer in the Department of Geology of Columbia University,1971-1972

Research Scientist, Lamont-Doherty Geological Observatory ofColumbia Univer si ty, 1970- 1971

Research Fel'o.v '..n Applied lvlechanics, California Institute ofTechnology, July 1969-September 1970

0-1

i~ „~t

M. D. TrifunacCurriculum VitaePage Tv'o

Research Assistant, California Institute of Technology,1966-1969

Research Assistant, Princeton University, 1965-1966Consultant to Advisory Committee on Reactor Safeguards,

1971-

Prof ssional Societies:

American Geophysical UnionAmerican Society of Civil EngineersSeismological Society of AmericaSigma XiEarthquake Engineering Research Institute

Teaching~ Experience:

Caltech: -2.

4,

Columbia Univer sity: l. .3'Ij 6940y '- Strong-Motion Seismology(1971-72)CE180 — Experimental Methods inEarthquake EngineeringCE181 - Principles of EarthquakeengineeringCE1 S2 - Str uc tura1. Dynamic s ofEarthquake Engineering

Other Selected Activities and Ewmerience:

Served on the Panel on Strong-Motion Seismology, Committee'n Seismology,'at. Acad. of Sciences; Participated. in UNESCOSymposium of Experts on Strong -Motion Seismology; Participated,in ATC-3 effort for improvement of Earthquake ResistantDesign Code; Presented over 50 scientific papers duringnational and international conferences.

0-2

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Scientific Publications of.M. D. Txifunac

1. 1967

Z. 1969

3. 1969

Analysis of accelerograms - Parkfield earthquake, with G. W.Housner, Bull. Seism. Soc. Amer., 57, 1193-1220.

'I

Analysis of strong-motion accelerograph records, with D. E.Hudson and N. C. iXigazn, Fourth World Conference onEa rthqua ke Engineering, Santiago, Chile.

Strong-motion earthquake accelerograms, digitized and plotted.data, Vol. I, with D. E. Hudson and A. G. Brady, EarthquakeEngineering Research Laboratory, EERL 70-20, CaliforniaInstitute of Te chnology, Pasadena.

4. 1969 Investigation of stxong eaxthquake ground 'motion, EarthquakeEng. Re s. Lab., Calif. Inst. of Tech., Pasadena.

5. 1970 Analysis of the station No. 2 seismoscope record - 1966,Parkfield, California, earthquake, with D. E. Hudson, Bull.Seism. Soc. Amer., 60, 735-794.

6. 1970

7. 1970

Wind and microtremor induced vibrations of a 22-story steelframe building, Earthquake Eng. Res. Lab., EERL 70-.01,Calif. Ins t. of Tech., Pasadena.

Complexity of energy release. during the Imperial Valley,California,, earthquake of 1940, with Z. N. Brune, Bull. Seism.Soc. Ame r., 6 0, 137-16 0.

8. 1970 Ambient vibration test or a 39-story steel frame building,Earthquake Eng. Res. Lab., EERL 70-02, Calif. Inst. of Tech.,Pasadena.

9. 1970 On the statistics and possible triggering mechanism of earth-quakes in Southern California, Earthquake Eng. Res. Lab.,EERL 70-03, Calif. Inst. 'f Tech., Pasadena.

10. 1970 Laboratory evaluation and instrument coxrections of strong-motion accelerographs, Earthquake Eng. Res. Lab., EERL70-04, Calif. Inst. of Tech., Pasadena.

11. 1970 Response envelope spectrum and interpretation of strong earth-quake ground motion, Earthquake Eng. Res. Lab., EERL 70-06,Calif. Inst. of Tech., Pasadena..

12. 1970 Low frequency digitization errors and a new method for zerobaseline correction of strong-motion accelerograms, EarthquakeEng. Re s. Lab., EERL 70-07, Calif. Inst. of Tech., Pasadena.

0-3

1971I

Response envelope spectrum and interpretation of strong earth-quake ground motion, Bull. Seism. Soc. Amer., ~61 343-356.

14. 1971

15. 1971

Zero baseline correction of strong-motion accelerograms, Bull.Seism. Soc. Amer., 61, 1201-1211.

A method for synthesizing realistic strong ground motion, BulL.Seism. Soc. Amer., ~61 1755-1770.

16. 1971 Surface motion of a semi-cylindrical alluvial valley for incidentplane SH waves, Bull. Seism. Soc. Amer., 61, 1739-1753.

17. 1971 Analysis of the Pacoima Dam accelerogram, Sm Fernando,California, earthquake of 1971, with D. E. Hudson, Bull. Seism.Soc. Amer., ~61 1393-1411.

18. 1971

19 1971

High frequency errors and instrument corrections of strong-motion accelerograms, with F. E. Udwadia and A. G. Brady,Earthquake Zng. Res. Lab., EERL 71-05, Calif. Inst. of Tech.,Pasadena.

Strong-motion earthquake accelerograms, II, corrected accelero-grams and integrated velocity, and displacernent curves, withD. E. Hudson,. A. G. Brady and A.'ijayaraghavan, EarthquakeZng. Res. Lab., EERL 71-51, Calif. Inst. of Tech., = Pa,sadena.

20. 1971 Engineering features of the San Fernando earthquake, February9, 1971, Chapter II, edited by P. C. Jennings,. Earthquake Eng.Res. Lab., "ZERL 71-02, Calif. Inst. of Tech., Pasadena.

21. 1972= Strong-motion accelerograms, III, response spectra, with D. E.Hudson and A. G. Brady, Earthqua.ke Eng. Res; Lab., EERL72-80, Calif. Inst. of Tech.

22. 1972 Strong-motion earthquake accelerograms, IV, Fourier spectra,with D. E. Hudson, F. E. Udwadia, A. Vijayaraghavan, andA. Brady, Earthquake Eng. Res. Lab., ZERL 72-100, CalU.Inst. of Tech., Pasadena.

23. 1972 Interaction of a shear wall with the soil for incident plane SH. waves, Bull. Seism. Soc. Amer., 62, 63-83.

24. 1972 A note on correction of strong-motion accelerograms forinstrument response, Bull. Seism. Soc. Amer., ~62 401-409.

25. 1972 Stress estimates for San Fernando, California," earthquake. of9 February 1971: itin event and thirteen aftershocks, Bull.

„Seism. Soc." Amer., 62, 721-750.

26. 1972 Tectonic stress and source mechanism of the Imperial Valley,California, ea,rthquake of 1940, Bull. Seism. Soc. Amer., ~621283- 13 02.

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0'ompaxisonbetween ambient and forced vibration experiments,Int. J. of Earthquake Eng. and Struct. Dynamics, ~l 133-150.

$",ud:es of strong earthquake motions and microtremor processes,with F. E. Udhvadia, 'International Conf. of i>iicrozonation,Seattle, Wa shington.

Analysis of errors in digitized strong-motion accelexograms,with F. E. Udwadia, and A. G. Brady, Bull. Seism. Soc. Ame'r.,o3, 157-187.

A note on scattering of plane SIC waves by a semi-cylindricalcanyon, Int. J. of Earthquake Eng. and, Struct. Dynamics, ~1

267-281.

Characterization of response spectra by parameters governingthe'ross nature of earthquake source mechanism, 53VCEE,Rome, Italy.

Recent developments in data processing and accuracy evaluationsof strong-motion acceleration measurements, with F. E. Udwadiaand A. G. Brady, 5V;CEE, Rome, Italy.--

Ambient vibration tests of full-scale structures, with F. E.Udwadia, 577CEE, Rome, Italy.

Comparison of earthquake and microtremor ground motionsin El Centro, California, with F. E. Udwadia, Bull. Seism.Soc. Amer. ~63 iso. 4, 1227-1253.

Analysis of stron~ earthquake ground motion for prediction -ofresponse spectra, Int. J. of Earthquake Eng. and Struct.Dynamics, Vol. 2, No. 1, 59-69.

The Fourier transform, response spectxa and their relationshipthrough the statistics of oscillator response, with F. E. Udwadia,Earthquake Eng. Res. Lab., EERL 73-01, Calif. Inst. of Tech.

Damped Fourier spectrum and response spectra, with F. E.Udwadia, Bull. Seism. Soc. Amer., 63, 1775-1783.

Routine computer processing of strong-motion accelerograms,with V. Lee, Earthquake Eng. Rcs. Lab., EERL 73-03, Calif.Inst. of Tech.

Characterization of response spectra through the statistics .ofoscillator response, with 1". E. Udwadia, Bull. Seism. Soc.Amer., ~64 205-219.

A three-dimensional d'slocation model for the San Fernando,California, earthquake of February 9, 1971, Bull. Seism. Soc.Ame r., 64, 149-172.

0-5

41.. 1974 Parkfield, California, earthquake of June Z7,'966: athree-dimensional moving dislocation, with F. E. Udwadia,Bull. Seism. Soc. Amer., 64, 511-533.

4Z. 1974 Time and amplitude dependent response of structures, withF. E. Udwadia, Intl. J. of Earthq. Engr.. and Struct. Dyn.~2 359-378.

43. 97 A A note on the accuracy of computed ground displaceznentsfrozn strong motion accelerograms; with V.. W. Lee,Bull. Seism. Soc. Ame r., 64, 12 09-1Z19.

44. 1974 Variations of strong earthquake ground shaking in the LosAngeles area, with F. E. Udwadia, Bull. Seiszn. Soc. Amer.,64 1429-1454.

45. 1974 Scattering of plane SH-waves by a sezni-elliptical canyon,with H. L. Wong, Intl. J. of Earthquake Engr. and Struct.Dyn., ~3 157-169.

46.. 1974 Surface motion of a semi-elliptical aQuvial valley forincident plane SH-waves, with H. L. Wong, Bull. Seism.Soc. Azner., 64, 1389-1408.

47. 1974 Interaction of a shear wall with the soil for incident planeSH waves: elliptical rigid- foundation, w th H. L. Wong,Bull. Seism. Soc. Amer., ~64 1825-1842.

48. 1975 An array of .strong znotion accelerographs in Bear Valley,California, with R. J. Dielznan and T. C. Hanks, Bull.Seism. Soc. Amer., ~65 l-lZ.

49. 1975 A note on the dynamic response of rigid, embeddedfoundations, with J. E. Luco and'. L. Wong, submittedto Intl. J. of Earthquake Eng. and Struct. Dyn.

50. 1975 On the correlation of seismic intensity scales with thepeaks of recorded, strong ground. motion, with A. G. Brady,Bull. Seism. Soc. Amer., 65, 139-162.

51. 1975 On the correlation of seismoscope response with earthquakemagnitude and Modified iviercalli intensity, .with A. G. Brady,Bull. Seism. Soc. Azner., 65, 307-321.

52. 1975 A study on the duration of strong earthquake ground motion,with A. G. Brady, Bull. Seism. Soc. Amer., 65, 581-626.

53. 1975 Two-dimensional, antiplane, building -soil-building interactionfor two or more buildings and for incident plane SH-waveswith H. L..Wong, submitted to Bull. Seism. Soc. Amer.

0-6

Correlations of peak acceleration, velocity and displacementwith earthquake magnitude, distance, and site conditions,with A. G. Brady, Intl. Z. of Earthquake Engr. and Struct..Dyn. (in press).

On the correlation of peak accelerations of strong motionwith earthquake magnitude, epicentral distance and siteconditions, with A. G. Brady, Proc. U. S. National Conferenceon Earthquake Engineering, Ann Arbor, Michigan, 43-52.

Preliminary analysis of the peaks of strong earthquake groundmotion - dependence of peaks on earthquake magnitude,epicentral distance and the recording site conditions, Bull.Seism. Soc. Amer. (in press).

t.ull scale" three-dimensional tests of structural deformationsduring forced excitation of a nine-story reinforced concretebuild ng, with D. A. Foutch, Z. E. Luco, and F. E. Udwadia,Proc. U.S. National Co'nference on Earthquake Engineering,Ann Arbor, Michigan 206-215.

An experimental study of ground deformations caused, bysoil-structure interaction, with Z. E. Luco and F. E. Udwadia,Proc. U. S. National Conference on Earthquake Engineering,Ann Arbor, Michigan, 136-145.

Influence of a canyon on soil-structure interaction, withH. L. AVong, J. Engr. Mech. Div., ASCE (in press).

Antiplane dynamic soil-bridge-soil interaction for incidentplane SH-waves, with A. M. Abdel-Ghaffar, Intl. Z. ofEarthquake Eng. and Structural Dyn. (in press).

p

A note on the rang e of peak amplitude s of record edaccelerations, velocities and displacements with respect tothe Modified Mercalli intensity, Earthquake Notes (in press).

Contact stresses and ground motion generated by soil-structureinteraction, with H. L. Wong and J. E. Luco, submitted toIntl. Z. of Earthquake Eng. and Struct. Dyn.

Preliminary emoirical model for scaling courier amplitudespectra of strong ground acceleration in terms of earthquakemagnitude, source to station distance and recording siteconditions, Bull., Seism. Soc. Amer. (in press)..

Dependence of duration of strong earthquake ground motionon magnitude, epicentral distance, geologic conditions atthe recording station and frequency of motion, withB. Westermo, submitted to Bull. Seism. Soc. Amer.

0-7

~ i ~ ~

65. 1976 On the comparison of experimental and theoretical analysesof the effects of surface and subsurface „irregularities onthe amplitudes of monochromatic waves, with H. L. Wongand B. Westermo, submitted to Bull. Seism. Soc. Amer.

66. 1976 Correlations of frequency dependent duration of strongearthquake ground motion with the Modified Mercalli.Intensity and the geologic conditions at the recordingstations, with B. Westermo, submitted to Bull. Seism. Soc.Amer.

67. 1977 'n instrumental comparison of the Modified Mercalli (M. M. l. )and Medvedev-Karnik-Sponheuer (M. K. S. ) Intensity scales,Sixth World Conf. Earthquake Engineering, New Delhi, India.

68. 1976 Effects of cross-axis sensitivity and misalignment on thexesponse of mechanical-optical accelerographs, withH. L. AVong, submitted to Bull. Seism. Soc. Amer.

69. 1977 Antiplane dynamic soil-bridge-soil interaction for incidentplane SH waves, with Abdel-Ghaffar, Sixth world ConferenceEarthquake Engineering, New Delhi, India.

70. 1977 Statistical analysis of the computed response of structural'response recorders (S. R. R. ) for accelerograms recordedin the United States of America, Sixth world ConferenceEarthquake Engineering, New Delhi, India.

0-8

I~/ J I

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~ ATTACHMENT P

~ ~

REYIG'f OF TllE 'SEIShlIC EYALUATION FOR

~ POSTULATED 7.5hf IlOSGRI EARTNQUA}:E,

UNITS l AND 2, DIABLO CANYONSITE'y

J. Enzique Luco

A Rcport to the Advisory Committee on Reactor SafeguardsU. S. Nuclear Regulatory Commission.I

~ 1

50 hhy 1978

REYIEIf AND RECONlENDhTIONS

After dctailcd review of thc rcport 'Seismic Evaluation forpostulated 7. 5~if llosgri Earthquake'Rcf. 1),. I have thc following

comments and rccommcndations:

l. Frcc-Field Desi .n Sncctrum. In my opinion, the frcc-

field design spectrum used for rc-evaluation of thc Diablo Canyon

Nuclear Power Plant docs not reflect the strong motion at thc sitefor a 7.5 magnitude earthquake at an epicentral distance of 5

kilometers, but rather the motion for a 6.Sic earthquake at thatdistance. The free-field design spectrum developed by Newmark

and adopted by NRC corresponds to a simplified version oi the

average of the two Pacoima Dam spectra recorded during the6.5A'an

Fernando earthquake with the high-frequency portion reduced

by use of'n 'effective'eak acceleration (Fig. 1). Thc Blunts

design spectrum developed for the applicant closely follows the

Newmark spectrum. The peal; acceleration, velocity and displace-I

'entcontrolling the high, intc'rmcdiate and low ircqucncy portions

of thc Ncwmark design spectrum arc in agrccmcnt with the average

(50'ercentile) peak valdcs obtained by Trifunac (Ref. 2) for ah

6.5ht earthquake while falling short by 40 to 60 percent from the

corresponding values for a 7.5hf earthquake (Table 1). The peak

values consistent with thc Ncwmark spectrum arc also considerably

lower than those 'suggcstcd in USGS circular 672 (Rcf.. 3) as shown

in Table'1. In addition, comparison of thc Ncwmark and Blumc dc-

sign spectra with cstimatcs of thc avcragc rcsponsc spectrum for

qo~ ~ ~ I ~

~ P-2I

~ n ' ~

a 7.5)4 carthquakc as obtained by Trifunac (Rcf. 4) also shows

diffcrcnccs of thc order oi 30 to 50 pcrccnt (Fig. 2).

The applicant has indicated that thc thrust fault mech"nism

and thc location of the Pacoima Dam instrument in thc San

Fernando earthquake may have incrcascd thc recorded peak acccl-

eration. These possible cficcts arc ncgligiblc in view of thc

fact that the standard deviation for peak accclcrations, which

has,not been considered, corresponds to a factor of 2. Also, thc

records ior thc hfs=7.2 Gazli, Russia earthquake of 1976 indicate a

peak horizontal acceleration of 0.8g at an epicentral distance of

10 kilometers. Correcting for attenuation using the Gutenberg's

relation leads to a peak acceleration of 1.0g at 5 kilometers for

thc Gazli earthquake in general agrcemcnt with the results of

Trifunac and thc USGS rccommcndation (Table 1).

Xn view of these facts, I must, conclude that thc Ncwmark and

Blumc design spectra do not corrcspond to the ground motion for a

7.5'arthquake at an epicentral distance of 5 kilometers. I pro-

pose that the estimate of the average response spectrum for 51=7.5,

5 kilometers, epicentral distance and rock sites of Trifunac (Rcf.

4) bc used as design spectrum. This spectrum is consistent with

thc only records availablc for large magnitude and short epiccn-

tral distances (San Fernando, Koyna and Gazli) as well as with thc

USGS circular 672 rccommcndations.

2 ~ 'Efi'cctivc'eak Acceleration. A judgmental iactor has

bccn used to rcducc thc 1.15g peak accclcration rccommcndccl in

USGS circular 67 to a value oC. 0.75g. This ill-dcCincd Cactor

C

P-3

e

t

has bccn used in thc past to account for discrcpancics on thc

level of damage obscrvcd as compared with thc prcdiction ofordinary seismic analyses which do not account for thc effects of

soil-structure interaction, are based on nominal values for damp-

ing and strength, assume linear behaviour a»d do not include the

energy dissipation in partitions and other non-structural clc-

ments. This catch-all reduction factor. has no place in the de-

sign of carefully analyzed structures such as those xn nuclear

power plants. Factors which may reduce the response or thc level

of damage should be identified and properly included in thc struc-

tural models. In the case of Diablo Canyon, many of these factor .

have already been incorporated in thc analysis: use of tc-tstrength rather than nominal values, use of higher than common

~ damping values, reduction by scattering of waves by large founda-

tions and possible inclusion of ductility. Thc arbitrary reductio.-.

of the high-frequency components of motion affects the response

piping and equipment. I recommend the. elimination of this reduc-

tion of the input motion.

3. On thc Effect of Scattering of Navcs b Ric.id Foundations.

Thc high-frcquc»cy components of the free-field motion have been

reduced by thc so-called tau-filtering procedure to account by the

scattering of waves by thc supposedly rigid foundations. This

correction amounts to a reduction of the Ncwmark free-field design

spectrum by 20 to 30 pcrccnt for frcqucncics higher than 2cps.

Slightly lower reductions have bccn used in thc Blumc's spectrum.

Thc correction for foundation scattering effects is based on thc

~ ~

~ ~ g

P-4

assumption of a rigid foundation and horizontally propagating Sll

waves. Although thc a" sumption of a rigid foundation may bc rca-

sonablc, it must be rccognizcd that deviations from thc assumption

lead to localized higher stresses in thc lower portions of thc

diffcrcnt structures. The assumption of horizontally incident Sfl

waves is highly questionable considering that thc epicentral dis-

tancc is comparable with the focal depth. Under thcsc conditions,

the possibility of nearly vertically incident.waves may not bc

ruled out. For vertically incident waves the scattering by the

foundations is practically nonexistent given thc shallow embed-

ment.

Assuming for the sake of the argument that the seismic exci-

tation at thc site corresponds x~ horizontally incident Sll waves,

I find that thc reductions proposed by Ncwnark and Blumc arc too

high when compared with analytical solutions. For hori"ontallyincident Sll waves the reduction of thc translational components

of motion is coupled with thc pxistencc of a marked torsional

input to the structure (for details refer to the attached papers).

The applicant has included 'accidental'ccentricities of 5 and 7

percent to represent these torsional effects. The usc of an

eccentricity of 5 percent corresponds to thc use of a peak tor-sional acceleration at thc base of thc containmcnt of thc order

of 0.025 rad/scc2 as may bc infcrrcd from Table 4-5 of Pcf. '1.

This torsional accclcration corresponds to a tangential accclcr"

ation at thc base of thc containmcnt cxtcrior.of 0.025 x 70/52=

0.05g. Thc results of Ray and Jhavcri of URS/131umc prcscntcd in

~ P~

Fig. 56 of Appendix D39A, but not used in thc analysis, show thata peak torsional acceleration of thc order of 0.1 rad/scc corrcs-2

ponding to a peak tangential accclcration at thc base of thc con-

tainmcnt exterior of 0.2g 'would be morc appropriate. It may bc

concluded that thc use of a 5 percent eccentricity undcrcstimatcs

thc torsional input by a factor of four. This ob" crvation is con-

sistent with the original work of Ncwmark (Ref. 5) which indicates

that an eccentricity of the order of 25 percent would bc necessary

to represent the torsional effects induced by horizontally propa-

gating Sll waves. It must be mentioned that thc increase in peak

acceleration of 0.2g based on a more realistic estimate of the

torsional input more than compcnsatcs for thc reduction by tau-

filtering from 0.75g to O.G7g for the containment exterior.From the point of view of thc analysis of the structural re-

sponsc, it docs not seem adequate to introduce the torsional inpu-

thxough the usc of 'accidental'ccentricities. Such procedure

which )cads to thc coupling of thc torsional and translational rc-sponsc in essentially symmetric structures distorts thc rcsponsc

and thc natural frcqucncios of thc system. Thc effects of thc tcr-sional input may bc significant fo- the turbine building in .which

thc possibilit'y of portions of the structure undergoing inelasticdcformations may increase thc eccentricity.

If it is shown that thc seismic excitation at thc site cor-

I'csponds mainly to horizontally incident waves, thc reductions ofthc translational and torsional response should bc cvaluatcd on

thc basis of thc morc exact methods presently availablc. To

~ ~

include an cxaggcratcd reduction of thc translational motion with-

out incorporating thc full torsional cffccts is improper.

Soil-Structure Interaction. In Appendix D-LL3A of Rcf. 1,

thc applicant presents a comparison of thc results obtained by the

fixed base analysis of the axisymmetric containmcnt nodcl with tau-

filtcred spectra as input (F.B.Axisym.) with those obtained fron a

soil-structure interaction finite clcmcnt model with the NcwmarL;

free-field motion (without tau-filtering) used as surface'controlmotion (PLUSl<-SSI). Based on the results shown in Fig. 3A-1 of

Appendix D-LL3A, the applicant concluded that 'thc use of tau-

filtered inputs with fixed base models as used for seismic analys"s

of Diablo Canyon structures is conservative.'his comparison isnot valid, and the c'onclusion is not warranted by thc analysis.Ior a valid comparison, we must require that the fixed base axis-

ymmctric analysis and the fixed base PLUSll analysis give esscnti

thc same response cvcrywhcre except at high frequencies whcrc thc

fixed base PLUSll results not.irfcluding thc tau-filtering should be

slightly higher. This is not thc case as shown in Fig. 3 of thisrcport obtained from results shown in Figs. 3A-1 and 38-5 ofAppendices D-LL3A and D-LL33. Since thc fixed base PLUSll mod 1

is ~ inconsistent with thc fixed base axisymnctric model, no validconclusion as to thc effects of soil-structure interaction can be

obtained by comparisons of thc type

bc mentioned that it has bccn shown

shown in Fig .. 3A-l. It mus tthat two-dimensional models

such as PLUSll may undcrcstimatc thc rcsponsc at thc top of thc

structure by 30 to 50 pcrccnt.

P-7

~4'

In Appendix D-LL3B, comparisons arc prescntcd oi thc rcsponsc

for a fixed base and an SSI model both computed using PLUS)l andV

thc Ncwmark free-field spectrum (without tau- fi3.tcring) as controlmotion on thc frcc-surface. Assuminp that thc results prcscntcd

arc internally consistent, it is possible to draw some tentativeconclusions. Fig. 38-2 of Appendix D-LL38 indicates that'he pca);

accclcrations'n the containmcnt cxtcrior obt'aincd including thc

SSI effects are approximately 10 pcrccnt lower than those obtained

on a rigid base. Since thc SSI result" automatically include the

cffccts of scattering of waves by the foundation as well as the

ci'fccts of radiation damping into thc soil, it'ay be concluded

that the reduction of 20 percent (0.75g to 0.6g) by tau-eff ctproposed by Newmar)'nd a similar reduction used by Blumc arc not

conservative. Figs. 3B-3 and 38-4 of the same Appendix indicate

that thc story shear forces and overturning moments on the contain-

ment exterior obtained including thc SSI are equal or slightlyhigher than those obtained for t)ie rigid base PLUS)) model. In

this case, any reduction of thc fixed base results by tau-filteringwould underestimate thc stresses in thc structure.

Assuming that .he PLUS)i results are correct and consistent,it may be concluded that thc tau reduction proposed by Hcwmar)- and

Blumc ovcrcstimatcs thc reduction effects of wave scattering and

soil-structure interaction ior vertically incident shear waves.

Zn particular, .thc strcsscs computed on thc basis of spectra rc-duccd by tau-filtering would u»dcrcstimatc thc strcsscs that rc-

suit irom thc SSI PLUS)l analysis by at least 20 pcrccnt.~ I

~ ~

4 ~ ~ ' ~ ~ - ~ ~ 4 ~ ~ ~ . ~

The applicant has indicated that thc shear wave velocity at

the site cxcccds 3600 ft/scc. Thc low-strain and itcratcd '(or

strain dcpcndcnt) shear Waves velocities used in the PLUSll SGI

model are not rcportcd. I rcquost that this information bc made

available. In Appendix DLL-15 (Amendmcnt 53), a uni for'm. shear

Mave velocity of 3500 ft/sec. 'is used.

I recommend that the tau-filtering approach bc eliminated

and that a complete three-dimensional soil-structure analysis for

vertical and horizontally incident SH waves bc undertaken. This

approach Mill havo the advantage of producing realistic estimates

of. the eave scattering and torsional cffccts.The peak spectral response for the PLUSll fixed base analysis

occurs at a frequency of 5.3 cps i~hilc the corresponding frequency

for the axisymmetric fixed base analysis is 4.5 cps, indicating a

dificrence of 18 percent,. If this diffcrencc reilects tho accur-

acy with Which thc fixed base fundamental frcqucncy can bc compu-I

ted, then it iiould scorn that the peak Widening of the floor rc-

sponsc spectra of 5 percent on thc high frcqucncy side may bc in-@

sufficient. The PLUSll SSI resonant frcqucncy is 18 pcrccnt lo:~er

than the PLUSll fixed base frcqucncy. This aga n sccms to indica e

that the 15 percent poa1 vidcning of floor response spectra on thc

low frcqucncy side is not sufiicicnt.5. Seismic I:isk Anal scs. Scvcral seismic risk analyses for

'thc Diablo Canyon site have bccn pcrformccl. Thc cstimatcs obtained

for the Probability of cxccdancc of thc llosgri design spectrum dif-X'cr by two orders of magnitude. Thc applicant (Appendix D-LL 11)

P-9

~ ~~ ~

j ~d ~

estimates that tIic probability of cxcccding an 'cficctivc'ccel-eration of 0.75g in 50 years is O.l pcrccnt. Anderson and Trifuna.

(Rcf. 5) cstimatc that thc probability of cxcccding thc high-,

frcqucncy portion of thc llosgri design spectrum in 50 years varies

from 10 to 20 percent, depending on the seismicity model considcre:

Thc difference corresponding to a factor of 100 to 200 can bc ana-

lyzed by considering thc following factors:

(i) The applicant considers thc probability of cxccdance

of an 'effective'cceleration of 0.25g while Ander-

son and Trifunac use as a basis of refcrencc the

0.75g Hosgri design spectrum. The usc by thc ap-

plicant of an 'effective'ather than'instrumental'cceleration

of 0.75g reduces thc probability of ex-

ccdancc by a factor of four.

(ii) Thc usc of Blumc's SAW-IV 'and SA~il-V attenuation re-

(iii)

lations as opposed to thc usc oi thc Trif'unac's rc-

lations leads to reduction of thc probability of

exccdance by a factor of t'en.

Thc rest of thc diffcrcnccs corresponding to a iac-

tor of 2. 5-4 can be attributed to tbcdifierent'eismicity

models considcrcd.,

llavxng isolated thc causes of thc discrepancies in risk esti-mation, I icill discuss them in detail. I have indicated that thc

'reduction of thc peak accclcration to an 'cffcctivc'cvcl should

not bc used in thc analysis of nuclear power plants. For thc pur-

pose of estimating thc risk of exceeding thc llos gri design spectrum,

P-10

f

the anchor accclcration of 0.75g hould bc treated as actual peak*

acceleration. In this case, thc probability of cxccdancc in 50

years as obtained by Blume's analysis would bc of thc order of 0.4

percent (refer to Table 11.S, D-L). ll) rather than O.l pcrccnt.

Thc main source of differences in seismic risl'stimates can

bc associated with thc type of accclcration-magnitude-distance

relation used. Thc applicant's risk analysis is based on thc usc

oi the Blume's SAhf-IV and SAl)-V procedure. In my opinion, thisprocedure leads to accelerations which do not reflect the strong

motion in the near source region of large magnitude earthqua) cs.

IS one considers .the three largest earthquakes for which records

werc obtained in the near source region, onc finds that the ob-

served peak accelerations are three to tcn times larger than those

predicted by thc SAi~! IV-V procedure (Table 2). Since thc standard

deviation for peak accelerations corresponds approximately to a

Sactor of two, it may be concluded that the SA'1 procedure is not

valid in thc near source region'of large carthqua);cs. Table 2

indicates that Trifunac's relations lead to accurate estimates of

thc obscrvcd peak accelerations (the average ratio of obscrvcd to

predicted peal: acceleration is 1.07). Fig. 41-I oi Appendix D-LL

41 shows that thc usc of the SA~I procedure leads to probabilitiesthat arc 10 times lower than those obtained on thc basis of thc

Trifunac's. relations for thc same seismicity model. Thc, scismi-

to a prob ilb 11-

ycals of t)lc

order of 4 pcrccnt.

city model dcscribcd in Appendix D-LL ll leads then

ity of cxcccding a peal; acceleration of 0.75g in 50

~ g ~

~ ~ ~

Thc seismicity model used in Appendix D-LL ll i" based on the

seismic rccurrcncc relation obtained by Smith for Central Coastal

California (Appendix D-LL llA). These rccurrcncc relations arc

based on thc seismicity during thc period 1930-1975 and do not in-

elude thc 7.2H 1927 carthquakc in thc region. The rccurrcncc.curves

as shown in Fig. 11A- 2 of Appendix D-LL 11A undcrcstimatc thc

number of earthquakes with magnitudes larger than six, and arc

~ based on a nominal value for thc parameter b of 0.92. Additional

study by Smith (Appendix D-LL 45A) indicates that a more appropri-

ate value for b would be O.SS6. The parameter b which controls the

relative contribution of thc high magnitude earthquakes to the tota

seismicity has a'trong effect on the calculated risk. Thc usc of

b O.SS6 would increase the calculated probabilities by a factor of

two (r'cfcr to Table 45.3 of Appendix D-LL 45).

Thc seismicity model considered in Appendix D-LL 11 is consis-

tent with thc seismicity obtained in Appendix D-LL 41 usi'ng the

geologic record of fault disloca'tion (a=3.12 in D-LL ll, a=2. SO

based on 10 years record and a= 3.20 based on 20 x 10 years6

record in D-LL 41). The seismicity calculated on thc basis of the

geologic record of lateral fault slip docs not include the seismi-

city associated »'ith vortical slip along thc Hosgri fault. Hamiltor

(Appendix D-LL 41A) quotes a rcport by Earth Scicncc Associates in-

dicating that thc .'lateral slip was probably subordinate to vcrtica)

movcmcnt.'f this is thc case, thc seismicity should bc incrcascd

to account ior vertical slip.Considering all thc iactors mcntioncd, it sccms that thc

P-12

~ ~

probability of 10 to 20 pcrccnt in 50 years obtained by Anderson

and Trifunac properly reflccts thc seismic risl'f cxccdancc ofthc llosgri design spectrum.

f v ~

~ ~

~ H

. ~t-

v

REFERENCES

Seismic Evaluation for Postulated 7. Shf llosgri Eart hquakc,Units 1 and 2, Diablo Canyon Site, Pacific Gas andElectric Company. *

0

2. Trifunac, hf.D., "Preliminary, Analysis oi the Peaks of StrongEarthquake hfotion-l)cpcndcnce of Peaks on Earthquake hfag»i-tudc, Epicentral Distance and Recording Site Conditions,"Bull. Scism. Soc. of Aner., Vol. 66, pp. 189-219 {1975).

Page, R.A., D.hf. Boore, ff.B. Joyncr, and H.fV. Coulter,Ground hfotion Values for Use in the Seismic Design of thcTrans-Alaska Pipeline System, U.S. Geological SurveyCircular 672, 1972.

4. Trifunac, hf.D., "Forecasting th Spectra'1 Amplitudes of StrongEarthquake Ground hfotion," Sixth li'orld Conference on Earth-quake Hnginccring, Ncv Delhi, India, 1977.

5. Ncwmark, N.hf., "Torsion in Symmetrical Buildings,"

Fourth'forld

"onfcrence.on Earthquake Enginccring, Vol. II, A-5,Santiago, Chile, 1969.

6. Anderson, J.G., and hl.D. Triiunac, Uniform Risk AbsoluteAcccler4ion Spectra for the Diablo Canyon Site, CaliforniA Rcport to thc Advisory Committee on Reactor Safcguards,U.S. Nuclear Regulatory Conmission, Dcccnbcr, 1976.

'~ ~

ll p ~ i~i i ~,

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ThlSLE l. COMPARISON OX'AXIMUMGROUND MOTIONS

Peakvalue sused by

1Ncivma r.k

0.75

M = 6.5

Trifunac

0.69 (1.29)

USCSNo. 672

0.9Q

M = 7.5

Trifu»ac Uc,No

1,07 (2.00)

v (in/s cc)max23 (48) 39 39(84)

(in) 8(19) 16 12 (30)

~ ~

4'cxvmark, N. M., "A Rationale for Dcrelopn>cnt of Design Spectra for Diab'.oCanyon Reactor Facili(y," Appendix C, Supplcrncnt No. 5, SER, Diablo

~ Canyon Nuclear Pov:er Sta(ion Units 1 and 2, NRC, 1976.

Average (average'+ standard deviation) peak motion for rock at an cpiccntraldistance R = 7.5km b scd on l'rifunac, M. D., "Preliminary Analysisof (hc Peaks of S(ro»g I art!iquakc Ground Motion - Dcpcndcncc of Peaks

. on Ear(I]quake Magnitude, Epicentral Distance and l<ccordi»g Si(c Condi-tions," B.S.S.A., 66, 149-219 (1975). ~

Page, R, A., ct ai., "Ground Motion Values for Use in thc Seismic Dc ign~ of thc Trans-Alaska Pipeline System," Geological Survey Circular

67?, 1972,

~ ~

~ ~

~ ~

P-15

TABLE 2. 'Com arison of Recorded and Predicted Peak Accelerations

RecordedPeakAccel.

SAW ry —SA,4 V(4)

Predicted RatioPeak Observed/Accel. Predicted

Trifunac( )

Predicted RatioPeak Observed/Accel. Predicted

1971 Pacoima( )

1967 Koyna

... i( )

1.25g

0.63g

0.80g

0.1248

0. 213g

0. 190g

10.08

2.96-

4.21

0. 839g

0.766g

0.900g

1.49

0.82

0.89.

5.75 1.07

(1) hf=6.5, epicentral distance 3 km, focal depth 15 km.(2) h! 6.5, epicentral distance 5 km, focal depth 5 km (assumed).(3) hl =7.2, epicentral distance 10 km, focal depth 25.km..(4)~Ys 12,000, 6 2.04,y 0(5) s 2s p 0.50 '

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Frequency, cps

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~ ~ F[Q. 1 —DESTGi4 5P" CTRUM COMPARED 71HH PACOMADAiVi.SP" CTRA, 2 PERCENT DAi&PPiiG,

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2.5

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0.5

0.2. 0,3 o.9

7 (sec.)

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,()

COetOV'rs ON SrISWIC OLSIGM LEVELSFOl( DIABLO CAliYOih SITI! IN CALII'OR'(IA

by'.D.

Vrit'uoac

April, 1973

~ ~~

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' '

Thc following convncnts deal with seismic design criteria for thc\

Diablo Canyon site in Califor»ia and rcprcsc»t a brief sunnnary of

my observations a»d prclitoi»ary co»clusio»s which a:c based o»

misccllancous written material and on a»unbcr of meetings during

the period starti»g in thc summer of 1977 and endi»g in April of

197S. Infoxtnatio» which I had on certain aspects of this effort

may bc incomplete. " The general picture and the summaries of thc

current status of this project ncvcrthclcss seem. adequate for thc

followi»g corrzc»ts and rccomrtcndations.

Huch has been written about dctailcd aspects of seismic design

criteria for thc Diablo Canyon site and it would b" impractical to

address again nun>crous points in detail and completely. Rather, I

will attempt to present an overall sunnnary of what I belicvc to be

unresolved problems at present, and what might bc possible avcnucs

to resolve them.

General Comments on thc Current In )uts and Criteria for Seismic Desi n

Gc»crally accepted «ss(nnption appears to bc that thc SSE on

Hosgri fault opposite thc plant site should bc an hi = 7.5 carth-

quake. This tnag»itudc, rcconnnc»dcd by USGS, has bccn dctcrmincd

mainly o» the basis of thc possible lc»gth of faulting o» thc

llosgri fault system.

2. Since hl= 7.5 at a (lista»cc of 5- 10 km from thc site leads to

large peak accc3cratio» (about l g) considerable effort has

bcc» dcvot'c(l t.o thc a»alyscs ldll)ch are desi g»('.(l to show that

Q-2

~ ~~ ~

these large amplitudes can a»tl may bc rcduccd throug)t considcra-

tion of t)tc fol)owing phc»omcna:

a) Scatt:ering and diffraction of hig)t ircqucncy waves from thc

foundations oE different plant structures .has bcc» proposed

as a vchiclc to justify reductio» of high frcquc»cy spectral

amplitudes (T cffcct). Thc manner in whiclt t:his .reducti.on

has bccn affcctcd rcquircs unrcalisti.c assumpt:io»s, for ex-

ample, that foundation is rigid. The manner in which t)tis

assumption is introduced into anal> sis if often on -sided

and considers mainly only t)iose consequences of t:hc physical

phe»omena w)tie)t lead to reduction.of spectral amplitudes.

Othcx co»sequences of this phenomcno», for example, torsional

and rocking cxcitatio»s of foundatio»»whic)t may amplify thco

structural response have been, so far, either overlooked or

treated inadcquatcly. T)tis has been achieved b> utilization

of dynamic models for'nalysis which are so deiincd that only

an incomplctc ph> sics of the problem, i.e., seismic excita-

tion and t)tc structural response, can bc. considered.

b) Thc term "effective peak accclcration" has bccn introduced

suggcsti»g tltat thc structure will "sce" somcthi»g smaller

t)tan actual peak accclcration. Thoug)t suc)t approach may bc

uscL'ul for cart,ltquakc rcsistcnt design of ordinary structures

by means oi t)ic rcsponsc spectrum tcclutiquc, thc term "cffcc-

tive peak accelcratio»" ltas not bccn dcfincd i» a way that:

would) c»able t)ic derivation of co»sistc»t results by scvcral~ ~

~ ~ Q-3

diffcrcnt cxpcrts in thc field. Si»cc thc proccdurcs for

scaling Regulatory Guide ]..60 spectra arc based on maximum

vibratory ground acceleration" (as dcfincd in Appendix A)

this departure from routine design practices makes it diffi-cult to cvaluatc thc number and thc nature of thc conscqucnccs

which would result from such an approach.

c) Hypoccntral rather than distance closest to the fault has

beep used to cvaluatc peak and effective peak acceleration.

This assumption implies certain angles of approach of seismic

wave energy. These angles o'f approach should then be con-

sistent with thc extent to which "r effect" is allowed to

influence the spectral amplitudes. Little or no attention

seems to have been given to mutual consistency of these

assumptions and in some. cases, inconsistent assumptions have

been utilized. For cxamplc, deep hypoccntcr would increase

the distance at which peak acceleration is evaluated, thus

* reducing thc estimate of peak accclcrat'on amplitudes. This

would, however, alamo imply that the waves arrive towards thc

foundation almost vertically. In consideration of "T effect"

howcvcr, horizontal dimensions of foundations appear to have

bccn used implying horizontal incidcncc of waves.

d) Thc large dampi ng equal to 7'o has bccn adopted for dynamic

rcsponsc calculations. Though thc apparent damping for

thc comp)ctc soil-structure system, subjcctcd to carthquakc

excitation ma> bc much larger tluin 7"', inadcquatc basis has

been presented tn justify 7.; dangling in structural systems

~~

, Q-4"~

'l~

'4l

only. Sclcctio» of too large structural damping coupled with

only two-dime»siona1 or simple thrcc-dimcnsio»al analysis

of soil-structure interaction can lead to u»rcliablc rcspo»sc

estimates.

3. At least thrcc seismic risk studies have bccn prcparcd to cstimatc

thc probability of cxcccding the sclccted dcsig» criteria at thc

Diablo Canyon site (Blumc, Ang a»d Nc»mark, A»dcrso» and Trifunac).

These studies have produced results which, in some cases, differ

by as much as two orders of magnitude. Concurrent »ith the com-

parisons of thcsc studies,. considcrablc cfiort has bccn devoted .

to diifcrcnt details in the methodology emplo> ed in these calcula-

tions. Little or no explicit effort and discussion has bccn de-

voted to the models of seismicity which are essential input into

such calculations, evc» though this may rcprese»t thc most impor-

ta»t contribution to thc discrepancies among thc results of

diffcrcnt studies. I» some extrcme cases (c.g., report by Blumc

and )'iremidjian) claboratc work has bcc» carried out, apparently

in vain, to show that a particular method for scaling peak acccl-

cration (Trifu»ac, )976) supposedly leads to "too large" estimates

of peak acccleratio» irrcgardlcss oi thc fact that those results

of Trifu»ac (1976) have »ever been used and do not rcprcscnt a

basis for the dcrivatio» of seismic risk models by Andcrso». a»d

Trifunac. In thc rcport by A»g a»d Ncwmark, substa»tially

smaller tha» average seismicity has bcc» assumed»car, thc site.

This may lead to a» u»dcrcstimatc of Lctual risk.~ ~

~ ~ ~Q-5

I

C ~ E

Recommendations

A. Ground hfotion.'.

Dctcrministic approach based on thc assumption that an

earthquake oC magnitude )f= 7.5 or greater »i] 1 occur oppo-

site thc plant site should bc re-cvaluatcd. This magnitude

might be an indicator of thc cxtcnt of geologic faulting

phenomena but it is not necessarily thc most rcliab)e basis

for evaluating the nature of strong shaking close to the

fault. There arc numerous examples in literature of sig-

nificant differences between )I< and ))S, for example, > hich

arc based on short and long period seismic»aves, respectively.

Often studies have shown that larger earthquakes may bc

thought of as a sequence of several or many discrete events

»hich can sequentially tal'e place along a long fault. Finally,I'he

largest recorded acceleration, so f"r, has resulted for

h)< 6.5 only. For thcsc reasons, and from thc design vic»-

point, I »'ould prcfcr to adopt )I= 6.5 on Hosgri opposite thc

site and not hi = 7.5.

2. Near-field source theory (not a finite element or finitediffcrcncc model of thc source and its surroundings) could

be used in conjunction with the spectral analysis of strongP

motions recorded cl..cwhcre to cvaluatc the amplitudes of

response spectra indcpcndcnt oC. peak accc)cration estimates

or of seismic risk «nalyscs.

G. ~lies >on.".c:h

1. Three-dimcnsio»al soil-structure interaction analysis should

bc carried out. 'I'his si>ould be done assumi»g that thc frcc-

field response spectra for design result from i»cidcnt SII, SV

or ltaylcigh waves. For Sl} and SV excitation, horizontal,

vertical and 45 incidcncc a»alysis should bc considcrcd. This

approacl> would offer thc followi»g advantages:

a. The "v effect" if prcscnt will bc accou»tcd for correctly.

b. Torsional a»d rocking cxcitations will be included i»to

the analysi.s correctly.

c. The proximity of the cartIiquakc source and thc fact that

~ the waves most likely arrive hori"o»tally will bc accounted

for correctly.

d. Thc radiation damping i» thc soil will be introduced into

analysis properly so that thc high value of 7'or struc-

turcs would not bc rcquircd.

L'xccpt for thc fact that 7'o dam}ii»g is pcrmissi}ale accordi»g to thercgulati»}', }',uidc ].61, thi» high strucfur»l darn})i»g rccollllllcnded forthc seismic»»»lysis at tl)c Dial)lo Ca»yo». site has»ot I)ccn

justif-

iedd. Forced vihr»lio» test (avai 1»l>lc i» t}.S. a»il .1»p»n) data,where flic et lect. of sui }-structure i»ter»etio» «»d ili I fere»t modeof cncr},) i»I~»t i»to tl>e structure pluri»}, n» ex/crime»t, relativeto i»eide»t. «:» tl«I»»k~ w»vv." is»ot »econ»ted I'ur, may bc of litt]cus( )» rs'} al> I 1,'sl1 L»}', . LI'l. »e( l}» I LI»mI) I»} }» ~ ( rue t urus a»ll tht 1 jcompo»e»}, s I or sc l sm te 'I'csI)0»!4c c» I cul» C1 0»s .

Q-7

I,

p

C'y

I'

ATTACHHENT R

"IF. ~B g

UNITED STATES ~ DEPARTl)ENT OF THE INTERIOR

GEOLOGICAL SuRVEV-

ESTIYiATION OF GROUND i~OTION PARAMETERS

David H. Boore, Adolph A. Oliver III, Robert A. Page,

and William B. Qoyner

OPEN-FILE)REPORT

78-509

Prepared on behalf of the Nuclear Regulatory Cormission

This report is preliminary and has not been.edited or reviewed for conrormity ~vith

Geological Survey standards.

yggoGlCAL gg~,

~~ggi.o pARic

JUi'l 2 197S

Ll0RAG"

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m'I

~ 2

f

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'4 I'~

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<hqoake. The solid Mnes show the 70 percent predon interval for the'aqua

„»tude 7.1-7.? data set of this report. thost of the points in that data

e t

~

~

-.g9» u

~ ',> came from the magnitude 7.7 Kern County earthquake.

The amount of disagreement shown in Figures 47 and 48 is not surprising

~ j„view of the different assumptions, differ ent measures of distance, and"vs

~ ~ ~ ~

'dj fferent data sets used in arriving at the differ ent curves. The1

d jsagreement i s, as might be expected, the greatest at short di stances.

ESTIMATION OF PEN PARAMETERS AT

'HORT DISTANCES

6eneral comments. The regression lines given in a previous section of this\

report provide the means for estimating peak ground motion 'parameters at

distances greater than 5 km f'r magnitude 5.0-5.9 earthquakes, at distances

j. greater than 15 km for magnitude 6.0-6.9 earthquakes and at distances greaterv

than 40 km for magnitude 7.0-7.9 earthquakes. Unfortunately, most of theF

daniage from earthquakes can be expected to occur at shorter distances..

Attempts have been made, as described in the preceding section, to provide

%1

1„

yC

.r.'

~

'-rm

curves for estimating at shorter distances. For reasons given in the

Preceding section we do not have complete confidence in those curves. Me willnot venture our own set of curves, but will discuss briefly some of the

considerations bearing on ground motion estimates near the source. Further

discussion of these questions in greater depth is given by Boore (1974).

There have been a number of studies using simplified models of the

fault;ing process to set limits on the ground motion at the fault surface

(Housner, 1965; Ambraseys, 1969; Brune, 1970; Ida, 1973). Brune's (1970) near

source model assumes that rupture occurs instantaneously over the fault

'

I I

peat particie ve1oty is proportional to the sts drop andn') pile.

aqua s >00 cm/sec for a stress drop of 100 bars. The peak acceleration is

infinite q f all frequencies are included, but if frequencies above 10 Hz ares ~

filtered out of the acceleration pulse the peak value is 2 g. This is a

useful model for relating gr ound motion to the physics of the rupture process,

'ut it does not give firm upper limits. An argument can be made for larger

~tions if one takes rupture propagation into account (Ida, 1973; Andrews,

1976).. Furthermore, the peak values of ground motion may represent localized

hi h stress drops as Hanks and Johnson (1976) have suggested for peak19

acceleration. Such localized stress drops might easily exceed one kilobar.

..:":-..', The peak acceleration at the surface is limited by the strenoth of near

surface materials as has been pointed out by Ambrasey (1974). For sites near

the source underlain by soil material of low strength, this factor may control

the value of peak acceleration. This consideration may also apply to rock' ~ ~

sites if the rock is sufficiently weathered. Determination of tho limiting

acceleration, however, would require reliable measurement of the dynamic, inh ~

k.

situ strength of the soil at a particula'r site. In the absence of adequate

measurements one must presume that the acceleration could be at least as large

as 0.5g, which was recorded on a thickness of more than 60 meters

of'ater-saturatedalluvium at station number 2 in the Parkfield earthquake\

(Shannon and Wilson, Inc. and Agbabian Associates, 1976).~ ~

In the case of peak displacement, as pointed out by Trifunac (1976), ife I

,one assumes no overshoot, the peak is limited to less than one half the static

>slocation amplitude. The latter is known for many historical earthquakes

»d may be estimated as a function of magnitude (Bonilla and Buchanan, 1970).

The accelerogram recorded at Pacoima Dam during the San Fernando

R-3

\

<earthquake has major sign%>cance for near source groundWotion estimates.

The instrument is located only 3 km from the rupture surface at a rock site

~~ere the topographic relief is severe. The peak recorded horizontalI

acceleration is 1.25g, velocity 113 cm/sec, and displacement 38 cm. This is

1~ m

tpe only accelerogram ever recorded within 5 km for an earthquake of magnitude

as large as 6.4, and as such ought to have strong influence on estimates of

near-source ground motion. The possibility of topographic amplifica ion needs,

consideration. A two-dimensional finite-difference study by'Boore (1973)

suggests that the acceleration may have been amplified by as much as 50

Percent but that th'e velocity and displacement were relatively unaffected.

Given these considerations, it would be difficult for us to accept estimates

less than about 0.8g, 1'IO cm/sec, and 40 cm, respectively, for the mean values

of peak celeration, veloc't d'

~em ~tt rock sites within 5 km of

fault rupture in a magnitude 6.5 earthquake. Me recognize that these numbers

~ iepresent one earthquake with a particular focal mechanism and that estimates

are bound to change when more data becomes available. >le presume that the~ P. ~ s s.

statistical scatter about the mean will be at least as great for the near-in

sites as at the greater distances where data is available.

The accelerograph at Pacoima dam was only 3 km from the nearest point onm

t'he

rupture surface, but the nearest point was not the source of the peak

»tions. As noted previously the source for the peak velocity and for the

Peak acceleration are different points on the rupture surface separated by

Perhaps as much as 20 km (Hanks, 1974; Bouchon and Aki,,1977).

~ . Above magnitude 6.5 there are essentially no data for estimating the

effect of magnitude on near-fault peak acceleration, velocity and

4isplacement, other than the static fault offset divided by 2 as a bound on

II ~ \

~ ~

~ .. ~h g /, the peak d~ sp aoement . Conservatism requ ires the presumption or some [norease

wrath magnitude- Hanks and Johnson {1976) presented a set of peak accelert'ata

at. source distance of approximately 10 km for earthquakes in the

magnitude range 3.2-7.1. The only data point above magnitude 6 5 was for th

imperial Valley earthquake of 1940 which they assign a magnitude of 7.1 in

contrast to our value 6.4, so the data set can be applied to magnitudes

greater than 6.5 only as an extrapolation. The data set shows some dependence

of peak accelerations on magnitude, but Hanks and Johnson argue that the data

are consistent with the idea of magnitude-independent source properties. The

data plotted as the logarithm of peak acceleration against magnitude can be

fit by a straight line with a slope equivalent to an increase by a factor of

1.4 per magnitude unit. This should not be used for extrapolation beyond

ccgnitude 6.5, however, because the data set was deliberately chosen to

represent relatively high values, and thus the slope of the line fitting the

data may not be the s arne as the slope of the line representing mean values or,

for. that matter o, of the 11ne representing values for any fixed probab lity.'.—.':-Atsites other than rock sites accelerations might be less because of

the limited stren tg h of near-surface materials, but, as previously noted,

determinin hog w much less would requ>re dynamic, in-situ measurements of soil

properties. The am plif~cation of peak velocity at soil sites compared t k

~ 'sites:may not b e so great close to the fault because of the energy lost in

nonlinear soil deform*

eformatlon, but numb:.ical modeling (Joyner and Chen, 1975)

demonstrates the possibility of amplification of velocity by as much as 30

«ent even under cond)talons of intense deformation. The possibility ofgreater am lificatp ion cannot be excluded. Anplification of displacement at

o<1 sites should b e expected close to the fault, -as at greater distances, if

. ~the soil column is sufficiently thick.

ACKNOWLEDGMENTS

We are grateful to R. P. Maley for assistance in obtaining information

0n strong motion recording site conditions and to A. G. Brady forunpublished'trong

motion data. R. B. Natthieson, T. C. Hanks, and A. G. Brady reviewed

the manuscript and suggested improvements.l

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