volume 3, number 2scecinfo.usc.edu/news/newsletter/issue32.pdflished, center scientists launched a...

Quarterly Newsletter

Volume 3, Number 2

Summer 1997

SS CC EE CCSouthern

CaliforniaEarthquake

Center

The RaymondFault Uncoveredat L.A. CountyArboretum—See Page 6

Southern California Earthquake Center

Southern California Earthquake Center Quarterly Newsletter, Vol. 3, No. 2, Summer, 1997

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The Southern California Earthquake Center (SCEC) activelycoordinates research on southern California earthquakehazards and focuses on applying earth sciences to earth-quake hazard reduction. Founded in 1991, SCEC is aNational Science Foundation (NSF) Science and TechnologyCenter with administrative and program offices located atthe University of Southern California. It is co-funded by theUnited States Geological Survey (USGS). The center alsoreceives funds from the Federal Emergency ManagementAgency (FEMA) for its Education and Knowledge Transferprograms. The Center’s primary objective is to develop astate of the art probabilitistic seismic hazard model forsouthern California by integrating earth science data.SCEC promotes earthquake hazard reduction by:• Defining, through research, when and where future damaging

earthquakes will occur in southern California

From the Center Directors . . .

What Is the Southern California Earthquake Center?

Center Director Science Director

• Calculating the expected ground motions

• Communicating this information to the public

To date, SCEC scientists have focused on the region’searthquake potential. Representing several disciplines inthe earth sciences, these scientists are conducting separatebut related research projects with results that can be piecedtogether to provide some answers to questions such aswhere the active faults are, how often they slip, and what sizeearthquakes they can be expected to produce. Currentwork focuses on seismic wave path effects and local siteconditions for developing a complete seismic hazardassessment of southern California.

Information: Call 213/740-1560 or e-mail [email protected]

SCEC GoesInternational?

A number of SCECscientists havediscussed the desir-

ability of adding an interna-tional component to the Center.They have argued that it wouldexpand our various databasesand broaden our intellectualframework. It also might allowus to test some of our modelsmore expeditiously. Thedownside would seem to becasting our resources morebroadly and lessening ourfocus on southern California.In addition, the “interactiveoverhead” of the Center wouldsurely increase.

However, there may beprofitable ways in which wemight expand internationallywith only a modest additionalexpenditure of resources:

First, we could expand ourVisitors Program to include,

explicitly, the internationalexchange of scientists, wherebythe Center would fund bothforeign visitors and travelabroad by some of our ownscientists.

Second, we might assess whatit would take to develop a first-generation, first-order seismichazard model for the world, orfor some particularly impor-tant region of the world. Alogical follow-on, perhapsunder some form of interna-tional funding, would be todevelop that model.

Third, and potentially mostrewarding, might be to chasecertain foreign earthquakes.

Because we may not haveanother major earthquake insouthern California in the nextfive to ten years and becauseearthquakes provide quantumleaps in our understanding of

fault rupture and seismichazard, should we not considerinvestigating major continentalstrike-slip and thrust earth-quakes elsewhere in theaccessible part of the world ifand when they occur?

If the answer is yes, then theCenter should develop a post-earthquake scientific plan justas we should do for earth-quakes in our own backyard.

These approaches to theinternational study of earth-quakes, in addition to their

scientific return, could signifi-cantly expand SCEC’s visibilityand be an important additionto our knowledge transferprogram.

Editor’s notes: See internationalarticles in this issue on pages24 and 27 (Iran and Panama).

We welcome comments fromour readers in response to thismessage, especially scientistswho chase foreign earthquakesor conduct studies in foreigncountries.

Should we not consider investigating majorcontinental strike-slip and thrust earthquakeselsewhere in the accessible part of the world?


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Looking Back and Marching ForwardSCEC’s Contributions to Knowledge Transfer

by Jill Andrews

The Knowledge Transfer Program’s staff (Mark Benthien,outreach specialist, and Ed Hensley, writer/editor, and I)tackle the task of converting scientific results into more

broadly understandable form. We make research socially relevant.We turn information into products.

But that makes it sound more one-way than it really is. StephenGould, scientist and social commentator, once said,

It is not possible to act like an objective fact-gathering robot,and if we think we can, we’re just deluding ourselves, andwe’re going to be more subject to the prejudices we don’teven know we have because we’re not scrutinizing them.

Gould was talking about the relationship between science andsociety. His overall point was that when things are working attheir best, the exchange of insight, realization, and understandingflows freely both directions. In fact, in all directions. That, in anutshell, is what the Knowledge Transfer Program is here for: toopen channels and keep ideas flowing.

As Knowledge Transfer Director for the Earthquake Center, I’moften responsible for describing the research conducted by Centerscientists and explaining its relevance and applicability. At times,just keeping up with what SCEC’s own researchers are doing feelsas though we are trying to move a mountain with teaspoons.Since each investigator submits an annual summary of studies inprogress, I have access to a great deal of information. That’s one ofour “mountains.” The sheer volume of archived data, technical

SCEC now enters the second half of its eleven-year life span as aNational Science Foundation Science and Technology Center.That means it’s time to assess our experience so far. It alsomeans that it’s time to plan for the next half of our life. I want todo that for the Knowledge Transfer portion of SCEC here in thisarticle: share some of ouraccomplishments and ourplans.

The SCEC KnowledgeTransfer mission is toheighten public awarenessand reduce earthquake lossesby transferring researchresults and products to thecommunity at large. To fulfillthis mission, we aim to createa transportable program thatorganizes the ever-growingknowledge bases of academicscientists, engineers, andsocial scientists and makessure that their work isapplied to reducing earthquake-related risks. We essentiallyhave two target audiences for our products: the community ofscientists and technical professionals working in related fieldsand the general public. In both cases, we aim specifically at ourregion first, but eventually at the entire world of scientists andthe national public.

In preparing for the future, our plan is to identify KnowledgeTransfer’s most successful and productive outreach efforts andthen to make sure we concentrate on what works and make itbetter. We plan to base all our efforts on the strong foundationwe’ve established, especially our extensive, growing network ofpartners, contributors, and collaborators. We work in a multi-disciplinary, multi-institutional research environment, and wehave gained expertise at translating scientific data and informa-tion into products and services for technical users and thegeneral public.

How Did We Begin?Early in the program’s history, we convened a group of expertswho aided us in identifying appropriate end-users for theCenter—our clients. They also helped us establish objectives:

• Initiate and maintain personal contact with researchscientists, engineers, social scientists, and end usersthrough meetings, workshops, seminars, and field trips.

• Form mutually beneficial partnerships and alliances.

• Network: exchange ideas and information with otherorganizations.

Jill Andrews and Mark Benthien

reports, and research papers in itself requires constant manage-ment to keep it organized so that it’s available and accessiblewhen needed for any purpose—technical or nontechnical. As forour “spoons”: you’re reading one, and you’re about to hear aboutothers.



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Knowledge Transfer continued.

• Disseminate products using multimedia tools and tech-niques.

• Promote sustainability through development of fundingsources.

SCEC’s Knowledge Transfer Program has proven to be aneffective information broker between the academic communityand practitioners, between earth scientists and engineers, andbetween technical professionals and public officials. As a result,the Center is becoming known for its effective partnerships withlocal, state, and national government entities, academic institu-tions, industry, and the media.

What Have We Accomplished?Before the Knowledge Transfer Program was formally estab-lished, Center scientists launched a seminar series in 1992.Building on that model and using the research results presentedin the science seminars, the knowledge transfer staff designedworkshops for targeted end-users. Since then the KnowledgeTransfer Program has been involved in organizing workshops orsymposia covering a variety of earth science and engineeringtopics and benefiting science faculty, post-doctorals, graduatestudents, and undergraduate students from member institutionsand affiliated institutions.

Following the 1994 Northridge earthquake, we cosponsored apublic workshop entitled “One Year after Northridge,” inpartnership with the Governor’s Office of Emergency Services.More than 300 scientists, engineers, public officials, disaster

preparedness and responseofficials attended. Theworkshop was an importantfocal point for both organizingthe research and lessonslearned from Northridge andfor sharing information aboutpreparing for future earth-quakes.

sored by the Structural Engineers Association of Southern Califor-nia (SEAOSC), the California Division of Mines and Geology(CDMG), and SCEC. The task force is studying the types ofvulnerable structures common to Los Angeles.

FEMA is funding the production of two booklets to be publishedin the coming year to make the public aware of the hazards posedby those structures during earthquakes. The task force has alreadytackled structures such as the ubiquitous tuck-under parkingbuildings (a well-known example is Northridge MeadowsApartments) and nonductile concrete buildings (e.g., concreteparking structures and some older office buildings). The task forceplans to encourage city council members to take action to protectoccupants of these types of structures.

We also cosponsored with CDMG the “Zones of Deformation”workshop. Participants represented a cross-section of the geologi-cal, engineering, and planning communities. The focus was toprovide advice to CDMG about establishing guidelines for thedelineation, evaluation, and mitigation of zones of deformation.Three issues were discussed: zoning—identifying and defining thehazard; site-specific hazard investigation; and mitigation.

The California Universities for Research in Earthquake Engineer-ing (CUREe) recently submitted a proposal entitled “EarthquakeHazard Mitigation of Woodframe Construction” to FEMA’sHazard Mitigation Grant Program (Northridge Earthquake). Thethree-year project will include these components: testing andanalysis, field investigations, building codes and standards,economic aspects, and education and outreach. As associateproject manager for education and outreach, I will work withCUREe to develop education and training for home owners,apartment building owners, officials, and others.

We also addressed requests from the insurance industry byforming a steering committee that designed insurance vulnerabil-ity workshops, focusing on evaluation and upgrading of currentmethods used by the insurance industry in measuring exposure.The first two workshops, held in 1995 and 1996, were attended bymore than 400 representatives from the insurance and reinsurance

We chose this venue to releasethe seminal Phase II Report—Seismic Hazards in SouthernCalifornia: Probable Earthquakes,1994-2024 and to conduct apress conference with theprincipal authors, whoexplained the significance of

the report. The Phase II report generated concern among city andcounty engineers, building officials, and planners, so we started aseries of vulnerability and seismic zonation feasibility work-shops. We presented information on the vulnerability of variousbuilding types, bridges, and lifelines to over 200 attendees at twomajor workshops in 1995 and 1996.

Those workshops led directly to a dialogue among structuralengineers, civil engineers, geotechnical engineers, buildingofficials, planners, and earth scientists that became the GroundMotion Joint Task Force, a 48-member task force jointly spon-



industries, as well as earth scientists and earthquake engineers.The workshops promote two-way communication and increasedunderstanding of the earthquake threat in southern California. Asa next step, we plan a series of small workshops focusing onspecific areas of concern to both primary insurers and reinsurers.

New and Innovative TechnologiesAs with any other effort that involves a high degree of coordina-tion and time-sensitivity, the emergency management communitymust incorporate new and emerging technologies in order to meetits ever-more-complex responsibilities. New technologies cangather, disseminate, and coordinate better and faster information.We have been involved with our partners in both the public andprivate sectors to design workshops that promote sharinginformation between the producers and the users of thosetechnologies. Emergency managers can find out what’s out thereto make their work more effective, and technology providers canfind out what is needed.

We conducted three workshops on geographical informationsystem (GIS) use for scientists, engineers, and governmentrepresentatives. Topics included comparisons of hardware andsoftware, and data disclaimers. We also cosponsored “Making theMost of New Real-Time Information Technologies in ManagingEarthquake Emergencies,” a workshop jointly hosted by SCEC,USGS, CDMG, California Emergency Services Association(SCESA), OES, and Caltech. Attendees included 125 emergencymanagement and response personnel and represented businessresumption and contingency planners, business and financecommunities, public information officers, and local governments.

The InternetThe SCEC site on the World Wide Web represents the ongoingresearch and results from all seven core institutions. It provideslinks to related web sites, including nine SCEC-supportedstandard databases. You can learn about our featured products,educational products, and project data. You can link to the 50institution members of the Earthquake Information Providers(EqIP) group and to many other interesting educational sites. TheSCEC site receives about 1,000 hits per month; the SCEC DataCenter receives about 100,000 hits per month. If you have accessto the Web, visit us at WWW.SCEC.ORG.

Community EducationOur outreach to the general public includes hosting a series oftown meetings sponsored by state senators. SCEC providesspeakers and materials that address the earthquake hazard, riskassessment, and mitigation steps. Each meeting is tailored withinformation about protecting the homes and the neighborhoodinfrastructure of a sponsoring senator’s district.

SCEC is also pilot testing a model program that provides informa-tion and guidance to entire urban neighborhoods to help residentsand homeowners become uniformly prepared to protect theirlives and property. The year-long pilot is being conducted bySCEC’s education and knowledge transfer staff in cooperationwith the USC Department of Psychology, which will be assessing

pre- and post-program attitudes in addition to the preparednesslevel of residents. The pilot is being conducted in a low-income,ethnically and culturally diverse neighborhood near SouthCentral Los Angeles.

We believe in the importance of hands-on knowledge transfer. Aspart of our informal education effort, we conduct local fieldexcursions, highlighting seismic hazards for practicing profession-als (geotechnical, structural, and civil engineers); city, county, andstate officials; other scientists; high school and community collegeinstructors; utilities, transportation, and telecommunicationsindustry representatives; and public and private emergencypreparedness and response professionals. Accompanying fieldguides are published by SCEC’s Knowledge Transfer Program forpublic distribution.

See “Knowledge Transfer” on Page 20

James Dolan leading a field trip to one of his research trenches



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by Kristin Weaverreviewed by James Dolan

The Raymond fault,which trends east-northeastward beneath

the San Gabriel Valley, is one ofthe best-mapped faults in theLos Angeles metropolitanregion. Unlike most otherfaults in the area, which weremapped during petroleumexploration, the Raymond faultwas originally identifiedduring the search for a liquidthat is equally precious in aridsouthern California: water.

The fault forms a significantgroundwater barrier and wasoriginally thought to be a dikeor ridge of impervious rock(Conkling, 1928; Crook andothers, 1987). In 1940, Caltech

geologist John Buwaldaincluded the Raymond fault inhis study of the Raymondbasin for the Pasadena Waterand Power. More recently,Richard Crook and his col-leagues conducted a detailedtrench and geomophologicalstudy of the Raymond fault.This work was published as aUSGS Professional Paper in1987.

The most recent work on thisfault is going on as you readthis article. I am currentlyconducting my own graduateresearch on the Raymond faultwith Dr. James Dolan of theUniversity of SouthernCalifornia (see photos). TheRaymond fault is of greatinterest to our research groupand to the Southern California

Earthquake Center because itlies beneath a densely urban-ized region and is active, aswas shown by the 1988Pasadena Earthquake (ML 4.9)(Jones and others, 1990).

The Raymond fault is a left-lateral strike-slip fault (Jonesand others, 1990) that extendswest from the Sierra Madrereverse fault system for 20 km.For most of its length theRaymond fault separates latePleistocene alluvium on thenorth from early Holocenealluvium to the south. The onlyexceptions are on its ends,where it displaces older rocks.In the west these older rocksare Tertiary Topanga forma-tion, which make up most ofthe hills in the Highland Parkregion. To the east, north ofMonrovia, the fault juxtaposesmuch older rocks—theCretaceous Wilson Diorite—against alluvium (Crook andothers, 1987).

This spectacular fault geomor-phology continues into thegrounds of the Los AngelesCounty Arboretum (seephotos), where there is anotherpressure ridge caught betweentwo fault splays. Baldwin Lake,which has been described as asag pond (Buwalda, 1940;Crook and others 1987), sitsbetween these ridges. West ofthe pressure ridges, theRaymond fault exhibits a low,diffuse scarp that has severalprominent left-lateral streamchannel offsets (Buwalda, 1940;Jones and others, 1990).Buwalda reported that one ofthese streams shows about424␣ m of displacement; Jones’party found that other chan-nels appear to have beensimilarly offset.

Fault of the Quarter

The Raymond Fault

Length: 20 km

Slip Rate: unknown

Cumulative Offset: min. .42 km horizontal and .78 km vertical

Maximum Magnitude: 6.75 (preliminary estimate)

Recurrence Interval: max. 4,500 yr.

Fault Stats

San Marino

California Institute Of Technology

Huntington Library

Botanical Gardens

El Molino ViejoLacy Park

<- Sierra Madre Blvd

<- Huntington Dr

Crook and others mapped twoanastomosing strands of thefault from east of Sierra MadreBoulevard through thesouthern part of HuntingtonGardens. These meet againwest of Sierra Madre Boule-vard in San Marino and runalong the northern side of LacyPark. The hill along thenorthern edge of Lacy Park is

If you trace the Raymond faultthrough the cities of Monrovia,Arcadia, Pasadena, SanMarino, South Pasadena, andthe Highland Park region ofLos Angeles, you notice themany geomorphic features thatcharacterize it. On its easternend, the fault runs along thebase of a prominent crystallineridge that forms the northernedge of Monrovia (Crook andothers, 1987). Continuing to thewest, the fault scarp is ob-scured by recent deposition inthe Santa Anita Wash, but itcan be picked up on the otherside of the wash, where itforms the 15-m-tall hill alongthe northern edge of SantaAnita Racetrack. At that point,two splays of the fault bound alinear hill called a pressureridge that has popped upbetween them (Crook andothers, 1987).



the Raymond fault scarp. Justeast of the park, at HuntingtonGardens, the fault scarpexhibits upwards of 25␣ m ofrelief, providing HuntingtonEstate with its wonderfullocation, overlooking LosAngeles. My advisor refers tothe Raymond fault as the mostbeautifully landscaped fault inthe world. One look at Hun-tington Gardens in San Marino,and I think you will agree.

From Huntington Gardens toHighland Park, where the faultappears to splay into severalwest-trending strands, theRaymond fault appears to be asingle strand. In this reach, thefault separates TertiaryTopanga formation from earlyHolocene alluvium (Crook andothers, 1987). One of the mostprominent hills along thisstretch of the fault is RaymondHill, for which the fault isnamed. Weber (1980) mappedthe Raymond fault in thisregion, bringing it through thevalley south of OccidentalCollege.

During their study in the late1970s and early 1980s Crookand others attempted toquantify slip on the Raymondfault. After examining well logsand excavating severaltrenches across the Raymondfault, they determined that thefault has had up to 775␣ m oftotal vertical displacement, aswell as a significant, butunquantified amount of lateraldisplacement. In their trenches,Crook and others foundevidence for at least fiveevents, and perhaps as many aseight events on the Raymondfault that could have accommo-dated this displacement. Theoldest event was dated at35,800 ± 1,300 yr. B.P. and theyoungest appeared to disturbthe surface soil, from which abulk-soil age of 1,630 ± 100 yr.B.P. was obtained.

earthquakes on the Raymondfault in the last 36,000 years,the average recurrence intervalis ~4,500 years (Crook andothers, 1987). If additionalevents have occurred, therecurrence interval would beshorter. Using a fault-planearea of ~325␣ km2, Dolan andothers (1995) suggested thatrupture of the entire Raymondfault, by itself, could generate aMw 6.7 earthquake. Such anevent would be expected toproduce ~1.7␣ m of slip. One ofthe main foci of our presentstudy is to determine whetherthe Raymond fault typicallybreaks in such moderate eventsor whether it participates ineven larger earthquakes thatmay involve other nearbyfaults, such as the Sierra Madreor Hollywood faults.

On the basis of the consistentlysouth-facing fault scarpstogether with evidence fornorth-side-up displacements,Crook and others (1987)suggested that the Raymondfault is a high-angle reversefault. However, the 1988Pasadena earthquake focalmechanism shows nearly pureleft-lateral motion on theRaymond fault (Jones andothers, 1990). It is still un-known at this time how theRaymond fits in kinematicallywith the other faults in theregion. The Raymond faultmight act as a tear fault,transferring slip from the SierraMadre fault to the Verdugofault, with the help of the EagleRock fault. On the other hand,it may continue past the EagleRock fault and connect withthe Hollywood fault alongtrend to the west of the LosAngeles River. However, asimple, thoroughgoingconnection between theRaymond and Hollywoodfaults cannot be established bygeomorphic mapping (Dolanand others, in press).

Dolan Receives Zumberge Research Grant

James Dolan, assistant professor in the earth sciencesdepartment at USC and member of the SCEC Board ofDirectors, was named one of three recipients of naturalsciences grants from the James H. Zumberge Researchand Innovation Fund. Established as the FacultyResearch and Innovation Fund by former USC presi-dent James H. Zumberge to enhance scholarship at theuniversity, the fund was renamed in Zumberge’s honorin 1991. It is the only university research money givento USC faculty.

The research seed grants are valued at up to $25,000and are intended to help untenured junior facultylaunch their research careers and provide asteppingstone to external funding agencies. The fundalso assists tenured faculty in changing researchemphasis or in resuming scholarship that has beendisrupted. It occasionally helps faculty working infields with inadequate funding sources.

See “Raymond Fault,” Page 23

MAP OPPOSITE PAGE:

A map of the San Marino area, showing landmarks near the Raymond fault.

PHOTO OPPOSITE PAGE:The trench was located just south and west of the Hugo Reid adobe dwelling on the grounds of the LosAngeles County Arboretum. The photo shows a part of the trench near the arboretum’s boundary (inmiddle distance) and shows part of the neighboring residential area in background.

BELOW:

Kristin Weaver and James Dolan inspect the trench wall.

photos by Jill Andrews

Assuming that these eightevents represent all the large



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There probably isn’t asingle SCEC scientisttrying to solve some

problem of southwesterntectonics and fault structurewho hasn’t pored over one ofthe gorgeous and colorfulgeologic maps drawn by TomDibblee. Besides their aesthet-ics, the insight and precisionbehind the maps makes themone of the most useful refer-ence tools available to research-ers in the earthquake commu-nity.

Mention Dibblee’s name tomembers of SCEC’s Group C(Earthquake Geology), andyou’ll probably hear a rareoutpouring of genuineenthusiasm for this man—words of gratitude and respect.

“Tom Dibblee’s achievement istruly extraordinary,” saysJames Dolan, University ofSouthern California/SCEC.“The scope of his 70-plus yearsof mapping is mind-boggling.The man has mapped half ofCalifornia in great detail. Hismaps provide an extraordinaryreference of the basic geol-ogy—in particular of southernCalifornia, which I use all thetime in my mapping of faultzones. For example right now,we’re using his maps exten-sively to understand exactlywhere the Oak Ridge fault is inthe Ventura basin. It’s one ofthe most rapidly moving faultsin southern California and it’scertainly capable of producinga large earthquake. His mapsprovide an amazingly easyreference for going into an areaand understanding the basicgeology very quickly.”

Hill in 1953 (that was beforefull acceptance of platetectonics, back in the dark agesof geology), in which hecontended that the cumulativeoffset on the San Andreas faultwas well over 100 miles—something not thoughtpossible at the time. Geologistsnoisily debated the merits ofthis conclusion for years. Now,of course, they all know he wasright.

Dibblee was also the first manto map the San Andreas fault inits entirety. In 1967, the USGSassigned Dibblee to map a 20-mile band on each side of the

fault. He traveled the 600-mile-long fault by foot. The nexttime you drive up Highway101 to San Francisco, look atthe passing hills and valleys,and consider that virtuallyeverything you see—hour afterhour even traveling at 65mph—was walked andmapped by Dibblee. In total,Dibblee has mapped over

40,000 square miles of Califor-nia on foot—a record that isunlikely to be surpassed.

We’ve all heard somethingbeing described as being wortha million bucks. In the case ofDibblee’s maps, it was morethan true. Based on Dibblee’srecommendations and maps,Atlantic Richfield (now ARCO)struck a 5,000-barrel-per-day

The Man Who Mapped Californiaby Michael R. Forrest

At 86, Thomas Dibblee is still gettinginto areas he’s mapping as healways did—any way he can. Hereand opposite, Dibblee is shown on arecent field trip.

photos courtesy Helmut Ehrenspeck

The San AndreasDibblee’s many monumentalachievements include a paperthat he coauthored with Mason

Tom Dibblee is perhaps the most amazing fieldgeologist to have ever mapped in the westernUnited States.



gusher with the first well theydrilled in 1948 in the Cuyumabasin. In gratitude they namedthe main producing unit ofsedimentary rock—the Dibbleesand—after the man who madeit all possible.

A Born GeologistBorn in 1922, the oldest of fourchildren, Thomas WilsonDibblee grew up on hisfamily’s historic Spanish landgrant, Rancho San Julian nearLompoc, California. Dibblee’slineage included Captain JoseAntonio de la Guerra yNoriega, who wascommandante of the presidioat Santa Barbara in 1800.Dibblee’s father was presidentof Central Bank and latermanaged a successful retailcomplex. Dibblee learned howto map when he was 13 fromHarry R. Johnson, a geologisthis family hired to look for oilon the ranch. He’s beenmapping ever since.

Dibblee graduated fromStanford University with adegree in geology in 1936.After working briefly for theCalifornia Division of Minesand Geology, he joined theUnion Oil company in 1937. In1949, at the age of 39, Dibbleemarried his boss’ livelysecretary Loretta Escabosa. Thetwo have been happily marriedever since. That boss, HaroldHoots, is himself an interestingfigure in the history of Califor-nia geology in that he appro-priated some of Dibblee’smaps, quit Union Oil, starteddrilling for oil as an indepen-dent, and became an extremelywealthy man.

with the U.S. GeologicalSurvey, for whom he mappedthe Mojave Desert, the SanGabriel and San Jacintomountains, the eastern andcentral Transverse Ranges, thesouthern Coast Ranges, and theentire San Andreas fault zone.

Roughing ItStories of Dibblee’s years in thefield have become the stuff oflegend. A solitary and quietman, Dibblee had no troublespending time away fromcities, towns, and people.When out mapping, Dibbleehad no use for hotels andrestaurants. He traveled light,unencumbered in all ways,

largest meal on the menu.“They wouldn’t let me leavethe restaurant until I finishedeating the steak,” said Dibblee.

After the USGS, Dibblee joinedthe faculty of U.C. SantaBarbara in 1977 and has beenthere ever since. From 1978 to1983, Dibblee also worked withthe U.S. Forest Service,eventually donating maps ofthe Los Padres National Forest(1.2 million acres) valued at amillion dollars. For that gift, hereceived the PresidentialVolunteer Action Award fromRonald Reagan.

“Tom Dibblee is perhaps themost amazing field geologist to

have ever mapped in thewestern U.S.,” says U.C. SanDiego geologist Tom Rockwell.“Having spent some time withhim in the field, I know that upuntil only a few years ago, hewould have run many of mystudents into the ground justtrying to keep up with him. Idon’t know anyone who hasn’tused his maps as the basis forcontinued research. They are atremendous resource.”

still mapping at the age of 86.Typically, now he goes out oneday a week with friend andDibblee Foundation drivingmember Helmut Ehrenspeck.Ehrenspeck is a gregarious,energetic geologist, cartogra-pher, and gourmet chef, who isas interested in the wildmushroom in the field as he isin the rocks. Dibblee limits hismapping expeditions indeference to his wife, whoworries about him when he’sout.

Dibblee and Ehrenspeck aremaking plans to map the PalosVerdes area. But neither isready to pinpoint the dates. Nodoubt, admiring L.A. basingeologists would followDibblee from outcrop tooutcrop, and he wouldn’t getanything done.

His maps provide an amazingly easy referencefor going into an area and understanding thebasic geology very quickly.

Why him? Why is it thatDibblee was the one whomapped more of Californiathan any other man or womanis likely ever to map? Ratherthan answer with backgroundon education, experience, orskills, Dibblee’s response ischaracteristically modest andfocused on the practical: “Inever met anyone else wholiked to be alone in the countrylike I did and have nothingbother me. I loved the soli-tude.”

Dibblee FoundationIn 1983 the Dibblee GeologicalFoundation was set up topreserve Dibblee’s work (seeHTTP://DIBBLEE.GEOL.UCSB.EDU/).The foundation publishesthousands of his maps ofCalifornia in a standardizedformat. At present it has issued66 of more than 80 maps (7.5-minute quadrangles) ofsouthern California.

No one who knows Dibbleewould be surprised that he is

over the mountains and acrossthe deserts.

He traveled into the field in his1946 Ford coupe. For provi-sions, he carried canned beans,bread, a couple of heads oflettuce, some raisins, and fivegallons of water. For accommo-dations, he sawed off thebottom half of the steeringwheel so he could stretch outbeneath it, his feet extendedout the car door on a woodenplank he carried for thatpurpose. No one would seehim for a couple of weeks.

An expense claim Dibbleesubmitted from one of thosetrips horrified his bosses. He’dbeen gone for a month,mapping the Imperial Valleyfor Richfield. His request forreimbursement totaled $14.92.“They were concerned I wasn’tgetting enough to eat.” Hisbosses drove him to a Mexicalirestaurant and bought him the

Dibblee mapped sedimentarybasins throughout Californiaand western coastal Oregonand Washington for theRichfield Oil Corporation,producing dozens of quad-rangles. Following that, hespent 25 (1952–1977) years



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Ralph J. Archuleta was bornin 1947 in Rock Springs, Wyoming.After taking his B.S. magna cumlaude in physics from the Universityof Wyoming in 1969, he obtained hisM.S. (1971) in physics and Ph.D.(1976) in Earth Sciences from theUniversity of California, San Diego.He is a professor at the University ofCalifornia, Santa Barbara, and hasrepresented UCSB as a director onthe board to the Southern CaliforniaEarthquake Center since February1991. After serving as associatedirector of the Institute for CrustalStudies at UCSB, he was recentlyappointed acting director.

He has served on the board of directors, as vice-president, and now president of theSeismological Society of America. He is a member of the American GeophysicalUnion, the Earthquake Engineering Research Institute, and the Committee onSeismology for the National Research Council, 1997–2000.He is the author of numerous publications, a few of which are mentioned in thisarticle. His research focuses on ground motion and site response; he and his grouphave recently produced some very compelling scenarios for the Los Angelesmetropolitan area.

Featured Interview with . . .

JA: Your academiccareer started out in physics.Why did you switch to earthsciences?

RA: While I was atUC San Diego, I began toquestion whether I was in theright field because my col-leagues didn’t seem to beworking as hard as I was. Inmy chosen field of magneto-spheric physics, there wereonly a handful of places wherejobs were offered. So I leftphysics and worked at SystemsScience and Software (“S-Cubed”) with Jerry Frazier onfinite element codes for wavepropagation in elastic media.One of the consultants therewas Charles Archambeau fromCaltech. He asked me tobecome a graduate student ingeophysics. But I’d just gottenmarried, and IGPP (San Diego)was closer. There I met JimBrune, who asked me to workon the problem of simulatingearthquakes using a dynami-cally propagating stress drop.

So I switched into strongmotion seismology, looking atwaves close to the source. Ofcourse, this has a lot of socialrelevance. An interestingcoincidence occurred: one yearinto my IGPP tenure, JerryFrazier was hired as a facultymember in the appliedmechanics and engineeringscience department at UC SanDiego. He became my otheradviser. I’ve never regretted

getting into this field of study.It has been very exciting—andit’s very easy to go to work.

JA: Let’s fast-forwardto your research focus today.As part of your SCEC involve-ment, you’re beginning aborehole strong motionprogram in the Los Angelesbasin. Could you explain thepurpose of this experiment?

RA: We have a lot ofinstruments that are on thesurface of the ground, but thereis very little information aboutwhat the incoming wave fieldlooks like. A lingering issue issite response—the effect ofground motion and its link tothe local site geology. Local sitegeology could be how muchalluvium you’re on or whatdepth it is. Or it could be howclose you are to the edge of abasing where the basin laps uponto mountains around it.

The Northridge earthquakeproduced the best data forwhat we had already identi-fied—that local site geology

we know is characterized bybasins filled with sediments.

JA: So it’s the type ofsoil?

RA: Yes. What wereally need is a baseline toidentify the incoming motion.We have to be able to say howmuch the incoming motionwas really changed by the localsite effect. To get the baseline,we need the boreholes. Rightnow, all instruments measurewaves at the surface, and evensurface rocks have an amplifi-cation all their own (seereferenced publications below).

We have active tectonics in thearea, and the rocks are “softrocks,” very weathered. So weneed baseline measurements.With those, we’ll have someidea of what input wave fieldwe should be looking at—whatis the amplitude of theseincoming waves. We can thenuse those recordings at theborehole sites and the record-ings simultaneously beingmade across the network to seehow much of a difference thereis between what we’re record-ing in the boreholes and what’shappening at the surface.

When we look at groundmotion, we know we’ve got thesource—that plays a major role.Then we look at the media

through which the seismicwaves travel. What we’refinding is that the crust ofCalifornia is fairly transpar-ent—the waves travel almostundistorted. They decay withamplitude, just as light decayswhen you shine a flashlight,but they’re not being distorted.As soon as the waves comeinto the shallow, sedimentarybasins or other alluvial fansand the like, we’re seeingtremendous changes in thesewaves.

JA: So are you sitingthe boreholes in areas whereyou’re expecting to see greatchanges?

I think the most difficult problem we face is howto correlate ground motion to damage. Damageis extremely nonlinear; it’s very difficult to predict.

Ralph Archuleta

Interviewed by Jill Andrews

greatly affects the groundmotion. In fact, seismic wavestraveling distances of 20,000–30,000 m can tremendouslychange their amplitude in thelast 10–30 m. So we’re lookingat something that is about atenth of a percent of thedistance traveled, and it’smaking a big change in theamplitude of the waves. So theissue is how to quantify the siteeffects in Los Angeles, which

RA: Initially we’resiting them only in the rock,because we’d like to identify‘true’ input ground motion(our baseline). Then we have alot of other stations withTriNet-type instruments nowbeing installed that we cancompare to. Again, TriNetdoesn’t have true baselinemotion.

This is exciting—we are, infact, developing one of the first3-D regional arrays. By 3-D, wemean instruments at depth,coupled with instruments atthe surface. Southern Califor-nia has some borehole instru-mentation sponsored by the



USGS and also my work for theUS Nuclear RegulatoryCommission and the FrenchCommisariat l’EnergieAtomique (CEA), but not onthe order that we will haveunder the auspices of SCEChere in Los Angeles. We planten sites, plus perhaps fivemore due to cost-sharing withother organizations, over thelife of the five-year project.

The primary investigators onthis project are Jamieson Steidland myself. Steidl is a researchgeophysicist here at UCSB’sInstitute for Crustal Studies(ICS). Having done his Ph.D.research using borehole data,he understands the require-

ments of instrumentation, thestrategy of the deployment andthe analysis of the data. I’vebeen putting instruments intoboreholes since 1984. We’recollaborating with theROSRINE project [Resolutionof Site Response Issues fromthe Northridge Earthquake; seeSQN 2.4:16], which is the NSF-sponsored project withCaltrans, PG&E, and othergroups. The USGS has aninterest in site effects as well, tocharacterize the site effects atall their strong ground motionsites. The whole point of thiscollaboration is to see whetherwe can get a uniform data set.

JA: In Los Angeles,how will your results be usedto determine what kinds ofbuildings will be affected?

RA: Site effects willaffect any given structure. Thefrequencies from the earth-quake will have their own

effect. As John Hall of Caltechonce said at an SSA meeting,“The earthquake will select itsown buildings.” Local siteconditions tend to play havocwith any sort of standardprediction.

I think the most difficultproblem we face is how tocorrelate ground motion todamage. Damage is extremelynonlinear, and it’s very difficultto predict—we leave that to theengineers to try to figure out. Ifyou design for a specificthreshold of damage but thatbuilding is subjected toearthquake damage, the samethreshold may no longer apply,because now you have a

completely different structure.It’s a moving target once it’sbeen damaged. The engineersknow what they need to designfor, as long as the buildingdoesn’t exceed its threshold—that’s what we can help with.We can say there will be acertain range of groundmotion, and they can designaccordingly. That’s the best wecan do right now.

JA: Your group hasdone some calculations topredict strong ground motionsfrom a scenario earthquake onthe San Andreas fault. Couldyou tell us about the result ofthose calculations?

EducationB.S., Physics—University of WyomingM.S., Physics—University of California, San DiegoPh.D., Earth Sciences—University of California, San Diego

ProfessionalGeophysicist, USGSProfessor, UCSBDirector, SCECActing Director, Institute for Crustal Studies

Honors & PositionsPhi Beta KappaPhi Kappa PhiWoodrow Wilson FellowPresident, Seismological Society of America

Recent PublicationsOlsen, K. B., R. J. Archuleta and J. R. Matarese (1995). Three-dimensional

simulation of a Magnitude 7.75 earthquake on the San Andreas Fault,Science, 270:1628–1632.

Theodulidis, N., P-Y. Bard, R. J. Archuleta and M. Bouchon (1996). Horizontalto vertical spectral ratio and geological conditions: the case of GarnerValley downhole array in southern California, Bull. Seism. Soc. Am.,86:306–319.

Olsen, K. B., and R. J. Archuleta (1996). Site response in the Los Angelesbasin from three-dimensional simulations of ground motion,Proceedings of the International Workshop on Site Response Subjectedto Strong Earthquake Motions, Jan. 16–17, Yokosuka, Japan, Vol. 2,Yokosuka, Japan: Port and Harbour Research Institute, 220–235.

Olsen, K. B., and R. J. Archuleta (1996). Three-dimensional simulation ofearthquakes on the Los Angeles fault system, Bull. Seism. Soc. Am.,86:575–596.

Steidl, J. H., A. G. Tumarkin and R. J. Archuleta (1996). What is a referencesite?, Bull. Seism. Soc. Am., 86:1733–1748.

Steidl, J. H., and R. J. Archuleta (1996). The 1989 Loma Prieta, California,earthquake: are geodetic measurements and rupture modelsconsistent? The Loma Prieta, California, Earthquake of October 17,1989—Mainshock Characteristics, U. S. Geological Survey ProfessionalPaper 1550-A, Ed. P. Spudich, A195–A207.

Oglesby, D. D., and R. J. Archuleta (1997). A faulting model for the 1992Petrolia earthquake: can extreme ground acceleration be a sourceeffect? Journal of Geophysical Research (accepted for publication).

Bonilla, L. F., J. H. Steidl, G. T. Lindley, A. G. Tumarkin and R. J. Archuleta(1997). Site amplification in the San Fernando Valley, CA: variability ofsite effect estimation using the S-wave, coda and H/V methods, Bull.Seism. Soc. Am. (accepted for publication).

earthquake on the San Andreasfault, and since that time,we’ve run others. We have runearthquakes for Santa Monica,Elysian Park, Palos Verdes,Northridge, and recentlyLanders. With Landers, wemodeled the actual magnitude7.3 earthquake of 1991. These

are all model results, and wehave ground motion at least forLos Angeles on these models.

Professional Highlights

RALPH ARCHULETA

We’re finding that the crust of California is fairlytransparent—waves decay with amplitude but arenot being distorted. However, as soon as theycome into the shallow, sedimentary basins orother alluvial fans, we’re seeing tremendouschanges in them.

RA: These are theresults that Kim Olsen initiatedas a SCEC post-doc. I hadfollowed his career very earlyon. Our interests stronglyoverlap, and Olsen has anefficient code. We ran asimulation of a magnitude 7.75

We were trying to show thestrong effect of the basins—thebasin effect is tremendous.There are early papers from1979 and 1980 by Rhett Butler,



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Hiroo Kanamori, MichelBouchon, and Kei Aki, inwhich they modeled the 1857San Andreas fault earthquake(the Big One for southernCalifornia). Both of thosepapers used a one-layermodel— basin effects excluded.Both acknowledged that thebasin could have a significanteffect. We modeled one-half ofthe 1857 earthquake, a 170-km-long segment of the SanAndreas that lies northeast ofLos Angeles. This work showsamplification of the surfacewaves due only to the velocitystructure and the basin effects.

One variable is the stress dropwe put into the model—nobody knows what it shouldbe. Landers, for example, has a200–230 bars stress drop. Thenumbers we used came fromthe SCEC Phase II report. Wehave a large stress drop;consequently we have largeamplitudes. The groundmotion can be scaled if betterestimates of the slip on thefault can be determined fromother means.

JA: And these resultsare accessible?

RA: Yes. Look at thesite HTTP://WWW.CRUSTAL.UCSB.EDU/~KBOLSEN, Olsen’s website. Ifyou use a Macintosh computer,use Sparkle software to run thescenarios. Play the scenarios athalf speed to get the full impactof the basin effect. Note thateven after the scenario earth-quake is over, the wavescontinue to bounce around inthe basin, much like watersloshing in your bathtub. Thisis what will cause an increasedduration in the ground motion.

JA: I understand thatthe Los Angeles basin wouldbe subjected to fairly strong orhigh amplitude long-periodwaves. What sorts of structuresmight these waves impact?

doesn’t crack; rather it rides thewaves, bobbing like a cork.These computer scenarios areinstructive for us; we don’tworry as much about the smallbuildings (the corks) such assingle-family homes. Thestructures we really worryabout are long structures, suchas bridges and high-risebuildings, which are muchmore vulnerable to long-periodwaves.

And the ground motion is notcontrolled just by the alluvium.The geometry of the basinrelative to the geometry of thefault that just moved is alsogoing to play a major role.We’re realizing that’s why it’salmost unpredictable. It’s notenough to know the local sitecondition—you have to knowthe geometry of what fault willmove relative to the fixedgeometry of the basin.

People generally treat earth-quakes as if they were anuclear explosion—a singlepoint from which all the energycomes. They point to thehypocenter or epicenter, whichto me, are the most misleadingpieces of information given tothe public. It gives the impres-

sion that something happened“here”—in a single spot. Infact, nothing happened at theepicenter—it’s often the placewhere there’s not the mostdamage. The epicenter issimply a point on the surface ofthe earth. The energy isactually released over theentire area of the part of thefault that ruptured. Whatmakes a San Andreas earth-quake so potentially damagingis that because of the fault’s

great length, it can releaseenergy over a huge area.

If we have a big earthquake onthe Santa Monica fault or anyone of the frontal fault systems,energy will be focused into LosAngeles. When you look at thegeometry of those faults, theyare dipping underneath theSan Bernardino and SanGabriel Mountains. When thatslip occurs, the energy will befocused into the basin, notaway from it, as it was in theNorthridge earthquake.Altadena, Pasadena, Azusa,Duarte could be in for someheavy hits.

JA: Are the ampli-tudes of these waves largerthan have been considered by

engineers in the past? Havethey designed and built forthese kinds of waves?

RA: Engineers basedmost of their information onpast earthquakes. They collectall the data they can, and theyplot the amplitude versusdistance for given magnitudeevents. Then they say, “Here’swhat we should expect.” Theproblem that Los Angelespresents is that we don’t havedata from large earthquakes inthis setting, with this geometry.The only way to make predic-tions about what groundmotions will be is, in fact,around these scenario earth-quakes. We need to run thescenario earthquakes to seewhat the effect is of the basinand the waves and the particu-lar characteristics of southernCalifornia.

JA: Is there anywhereelse in the world whereearthquakes occur in a basinsetting?

RA: The other place isTokyo. They are worried abouta repeat of the 1923 earth-quake, which was so devastat-ing. They have very deepsediments, and they worryabout the effect of groundmotion. Their records from the1923 earthquake indicate long-period waves, lasting severalminutes.

JA: Are they inter-ested in what you are doing?

RA: They are inter-ested in it—they have Olsen’scode and another one that waswritten by Rob Graves.

An overview look at the area of Los Angeles modelled by Ralph Archuleta and Kim Olsen to show thebasin effect during nearby earthquakes. An MPEG version of the model is available for viewing on theWeb at HTTP://WWW.CRUSTAL.UCSB.EDU/~KBOLSEN.

RA: Imagine ourstructures as boats in a stormyocean. A boat in a storm

JA: Who’s “they”?

RA: Private corpora-tions—large engineering firmsthat have to design tall build–ings, who have researchprograms and strong motioninstrument arrays. This is verydifferent from the U.S., wheremost of our research is done bygovernment or universities

Archuleta continued . . .



with minimal research supportfrom private companies.

JA: Nonlinear effects:there has been considerablediscussion in the SCECcommunity in the last coupleof years regarding the signifi-cance of nonlinear effects instrong ground shaking. Canyou tell us about the impor-tance of these effects and howwidespread these effects mightbe for different magnitudeearthquakes?

RA: Original researchon the nonlinear effect wasdone by Harry Seed (UCBerkeley) and Ed Idriss (now atUC Davis). They wrote a paperthat said the soil, under verylarge strain, goes nonlinear andchanges its properties. With thechange in its properties, itdampens the amplitude of thewaves. The soil actuallybecomes softer. When thishappens, it can take up more ofthe energy, and therebydecrease the amplitude of thewaves going to the surface. Theimplication of nonlinearity hasalways been that you coulddecrease the amplitude of thewaves. Ultimately, it willbasically put a finite value onacceleration—the accelerationcan only reach a certain level.In effect, it caps the accelera-tion.

Over the years, they havefound it is more complicated.For example, the clays inMexico City definitely did notbehave nonlinearly. They aresoft and slow but have a highplasticity index, so theyremained linear, even thoughthe amplitudes of the MexicoCity earthquake were verylarge.

phenomenon, you need a verydense array, preferably aborehole array. This is one ofthe things we’ll be looking atwith our borehole instrumenta-tion. A lot of questions remainopen as to what a nonlineareffect actually is—and howimportant it is. We know itexists—a simple example ofthat is that you make foot-prints. If you can leave afootprint, then it’s clearlynonlinear.

JA: If you can predictthe amount of energy releasedfrom an earthquake, andpredict nonlinearity’s effect atthe surface, i.e., less shaking,then would you be able topredict whether buildingswould suffer less damage fromthe dampening effect?

RA: Yes. The wholeargument has been that youcould dampen or decrease theamplitudes or accelerations orforces that will be felt in abuilding or structure if they go

through this nonlinear mate-rial. The issue is: does it? Andif so, how prevalent is it?

tion, the expected benefit ofnonlinearity (smaller ampli-tudes) is minimal.

JA: The strong motiondata center at UCSB is alsocataloging Empirical Greensfunctions. Can you tell us whatEGFs are, and how you expectto use them in the future forpredicting ground motions forfuture earthquakes?

RA: We’re storing therecords from the SouthernCalifornia Seismic Network(SCSN) that are on-scale. Mostdata coming into the SCSN areoff-scale—the instruments’primary purpose is locatingearthquakes, so there are veryhigh gains on most of theinstruments. As a consequence,when a good-sized earthquakeoccurs, the amplitudes areclipped. They cannot reach fullscale. However, for some ofthese stations, the amplitudesare faithfully recorded. We’retrying to put together a libraryof where an earthquake has

occurred, recorded on-scale,and then compile a completetime history. We then have aresponse of the earth betweenthat point in the earth and therecording site. The idea behindthe EGFs is that they have allthe information about what thepath and the local site condi-tion look like. Thus, to estimatewhat a future large earthquakemight produce for groundmotion, we can combine thesmall earthquakes using somealgorithm knowing that thepath and site effects (linear) arealready included in the originalEGF.

that occurred at a particularsite and make a site-specificprediction for that site for afuture earthquake somewherein this region. Those smallearthquakes have alreadyprovided recordings of thepath and site effects. The onlything missing is the source.

Alexei Tumarkin, Peng-ChengLiu (a SCEC post-doc), and Iare using these EGFs forNorthridge to invert for thesource function of the mainshock. We’re using methodsthat are reliable. We have somegood forward calculations, andwe have some realistic seismo-grams for big earthquakes. Thiskind of information can bevaluable to the insurance andreinsurance industries to assessrisk in an area of study.

About our strong motiondatabase: it is one of our mostimportant outreach programs.A recent survey of strongmotion data available showedthe only one that is up to dateand available on the Web is ourSMDB. It’s really only meantfor southern California, butwe’ve been expanding it toinclude more. We’re trying tomake it even more accessible.We think practicing engineersshould be able to look at thedata and download to theirown PCs to do something withit. Other databases aren’t asaccessible. There is no nationalor worldwide database forstrong motion. We’re trying toput one together—the reposito-ries exist, but accessibility isspotty. Our hope is that as wemake our own database moreaccessible, others will followsuit.

Ground motion is not controlled just by thealluvium. It’s not enough to know the local siteconditions—you have to know the geometry ofthe fault relative to the geometry of the basin.

The whole point was to showthat nonlinearity decreases theamplitude in soils. But as itcame out following LomaPrieta and Northridge, thematerial was linear to a muchlarger degree. The question is:at what level do soils gononlinear? To measure this

Something to remember is thatnonlinear effects almost alwayslead to less acceleration—butthey don’t necessarily lead toless deformation. If the soilgoes nonlinear (such aslandsliding, liquefaction,slumping), you can get a lot ofdamage from deformation.Also, if we look at the Rinaldisite after the Northridgeearthquake, which has thelargest velocity ever re-corded—170 cm per second—with 0.7 g—once you get tothat much, who cares? If thesoil can still transmit such largeparticle velocity and accelera-

That’s the idea. If we can makea library of these, then we canlook up all the earthquakes

JA: Tell us about thePortable Broadband Instru-ment Center (PBIC). Now thatit is five years old, how well isit being used? What segment ofthe SCEC community uses theinstruments, and what kinds ofexperiments are done with theinstruments? Are they kept in areadily deployable mode?



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RA: The PBIC nowhas 18 instruments. We just gotsome new sensors that measuremuch more long-periodresponse. The original plancalled for us to be at 25instruments after five years.But the board wanted us to

improve communications to beable to broadcast into the SCSNso that the data would auto-matically go into the network.That’s complicated, since theSCSN has fixed sites and oursare moveable.

The PBIC has been one ofSCEC’s success stories. ThePBIC has been invaluable forspecific studies. The SCSNcan’t simply readjust itsinstruments for this kind ofpurpose. We got tremendousdata following Northridge,Landers, and Joshua Tree. Wehave also used the instrumentsfor the Los Angeles RegionalSeismic Experiment (LARSE)—and they are currently de-ployed by Monica Kohler atUCLA, where she’s looking atLARSE Line 1, at teleseismsand local events. Also YangGang Li has used themextensively for his trappedwaves experiments, which aresuch an important part of howto characterize fault zones.Jamieson Steidl and JamesChin used them in one of thefirst characterizations of localsite effects in the Los Angelesbasin. They had them deployedduring the Northridge earth-quake and recorded the mainshock on several SCECrecorders. We have used themhere at UCSB to look at ourown local site response on

campus. We try to accommo-date everyone who needsthem. We don’t allow them toleave southern California, butthey are constantly used.

Hemispheric Conference of the Education Sector forSocial-Natural Disaster

Dear Colleague:

We would like to take this opportunity to bring you up to dateabout the latest news regarding the organization of the Hemi-spheric Conference of the Education Sector for Social-NaturalDisaster Vulnerability Reduction and the preparation of theHemispheric Plan.The conference will be held in Caracas,Venezuela, on September 15–17, 1997.

We would like to know if we can count on your participation inthe conference so we can better organize the event. There is nosupport available at this time to cover travel expenses of partici-pants; therefore, we encourage you to complete the activity formfor the Hemispheric Plan and send it to the area coordinator. Bypresenting the activity forms you can present the strategies andactivities that you or your organization are carrying out. Thesewill be considered in the preparation of the Plan.

We also want to inform you that, as part of the program at theConference, we have reserved September 16 from 2:30 P.M. to 5:30P.M. for technical discussions organized by participants related toissues regarding the proposed activities for the Plan (videopresentation, research, presentation of case studies, softwaredemonstration, etc.). If you wish to organize an activity as part ofthis program, we encourage you to communicate directly withProf. Mercedes Marrero for room reservation, projection equip-ment, or any other need. It is important to do this in advance.Please specify the type of equipment you need, the estimatedduration of the activity and the expected number of participants.You can contact Prof. Marrero at (58-2) 605-2011; Fax: (58-2) 285-1104; email: [email protected]

Participants should plan the hotel reservations on their own.

To facilitate hotel reservations, here are two of the suggestionsmade by the coordinator in Caracas:

1. Caracas Cumberland Hotel—Tel (58-2) 761-3660; Fax (58-2)761-6681; single or double occupancy room US$78/night

2. President Hotel—Tel (58-2) 708-8111; single or double occu-pancy room US$120/night

Please take note that these prices are valid until August 17.

We recommend that you maintain close contact with yourcoordinator listed below:

Academic Aspects: Jean Luc Poncelet

Tel (593-2) 464-629; Fax (593-2) 464-630; email [email protected]

Citizen Education: Ricardo Mena

Tel &Fax (593-2) 469-810; e-mail [email protected]

Physical Infrastructure: Stephen O. Bender

Tel (202) 458-3005; Fax (202) 458-3560; email [email protected]

Please feel free to contact us if you have question or comments.

Stephen O. Bender, Project Chief, Unit for Sustainable Develop-ment and Environment Natural Hazards Project, OAS.

Imagine our structures as boats in a stormyocean. A boat in a storm doesn’t crack, rather itrides the waves, bobbing like a cork. The struc-tures we worry about are long structures—bridges and high-rise buildings.

Archuleta continued . . .

ReferencesJ. H. Steidl, A. G. Tumarkin and R. J.

Archuleta (1996). What is areference site?, Bull. Seism. Soc.Am., 86: 1733–1748

Seale, S. H., and Archuleta, R. J.(1989). Site amplification andattenuation of strong ground motion,Bull. Seism. Soc. Am., 79: 1673–1696

Archuleta, R. J., S. H. Seale, P. V.Sangas, L. M. Baker, and S. T.Swain (1992). Garner Valleydownhole array of accelerometers:instrumentation and preliminary dataanalysis, Bull. Seism. Soc. Am, 82:1592–1621. (Correction ibid, 83:2039.)

Bonilla, L. F., J. H. Steidl, G. T. Lindley,A. G. Tumarkin and R. J. Archuleta(1997). Site amplification in the SanFernando Valley, CA: variability ofsite effect estimation using the S-wave, coda and H/V methods, Bull.Seism. Soc. Am, 87: 710–730.

Olsen, K. B., R. J. Archuleta, and J. R.Matarese (1995). Three-dimensionalsimulation of a magnitude 7.75earthquake on the San Andreasfault, Science, 270: 1628–1632.

Olsen, K. B., and R. J. Archuleta(1996). Three-dimensionalsimulation of earthquakes on the LosAngeles fault system, Bull. Seism.Soc. Am, 86: 575–596.

Olsen, K. B.. Web site containingscenarios showing the basin effectfrom an earthquake in Los Angelesarea. HTTP://WWW.CRUSTAL.UCSB.EDU/~KBOLSEN



.

Recent Barclay Jones Book Available

Economic Consequence of Earthquakes: Preparing for theUnexpected

Economic Consequences of Earthquakes: Preparing for theUnexpected, edited by the late Barclay G. Jones, wasrecently published. Jones examines the ramificationsof a large-scale earthquake in the U.S., while consid-ering preparedness options to minimize losses. Thispublication contains a preface by Jones and 15commissioned papers by experts in the fields ofseismology, engineering, sociology, business, andinsurance. The papers review and define:

• Earthquake problem in the U.S.

• Vulnerability of our built environment

• Impact of damaged and destroyed facilities onsocial and economic systems

• Precautionary measures to reduce exposure torisk

Economic Consequences of Earthquakes: Preparing for theUnexpected was published by the National Center forEarthquake Engineering Research in Buffalo, NY. Formore information, call (716) 645-3391.

WSSPC XIX Annual ConferenceNovember 4–7, 1997

Victoria, British Columbia

The conference policy sessions are structured around the develop-ment of seismic policy (government policy that relates to earth-quake hazards and mitigation). Each policy session will have briefpresentations by the speakers and extensive time for participantsto discuss and develop policy alternatives for the issues pre-sented.

Policy session topics:

Building Codes and Seismic Zonation

Hazard Loss Estimation and Scenario Development

Earthquake and Hazard Insurance

For information contact:

Western States Seismic Policy Council, 121 Second Street, FourthFloor, San Francisco, CA 94105phone 415/974-6435fax 415/974-1747email [email protected] web site HTTP://WWW.WSSPC.ORG

Risk/Insurance Journal Accepting Research Papers

Risk Management and Insurance Review is a new journal focusingon public policy, as it applies to risk management and insurance.Researchers interested in submitting papers to the new journalfor review or anyone interested in additional information cancheck the web at HTTP://WWW.ARIA.ORG/RMIR or email the editor,Claude C. Lilly: [email protected].

Barclay Jones, Author and Professor, Dies

Barclay G. Jones, Cornell University professor of city andregional planning and regional science, and a noted experton protecting historic structures from earthquake damageand on the social and economic impact of natural disasters,died on May 26 in Ithaca, NY. He was 72. The cause ofdeath was heart failure.

Jones was a native of New Jersey. He had taught at Cornellsince 1961. A member of the Earthquake EngineeringResearch Institute, he had served on the editorial board ofthat organization’s journal, Earthquake Spectra. Up until hisdeath, he was a member of the executive and researchcommittees of the National Center for Earthquake Engi-neering Research in Buffalo.

Jones wrote extensively about the social and economicaspects of earthquakes. His most recent work (see notice onthis page) was the NCEER publication Economic Conse-quences of Earthquakes: Preparing for the Unexpected.

He was an authority on earthquake damage assessmentand prevention. He was a key researcher in an NSF studyof the earthquake hazard in the eastern U.S., especially thebehavior of concrete and steel structures in earthquakes.

In 1992, The Barclay G. Jones Endowment for PlanningPrograms was established at Cornell. The fund supportsgraduate work in local planning to emphasize quantitativemethods of analysis.

Structural Geology & SeismologyHarvard University

The Department of Earth & Planetary Sciences ofHarvard University invites applications forPostdoctoral or Research Associate positions instructural geology & seismology. We seek candi-dates interested in (1) the development of regional3-D interval velocity models from seismic reflectionand sonic log data for forward modeling of earth-quake generated waves and seismic risk assesment,and (2) the characterization of active geologicstructures, including blind thrusts, through integra-tion of natural seismicity with industry seismicreflection profiles, well logs, and surface geology.

The application deadline is September 31; however,we will accept applications until the positions arefilled. For further information contact Prof. JohnShaw ([email protected]) or Prof. JeroenTromp ([email protected]). Applicationsshould be mailed to Kathy Harrow, Department ofEarth & Planetary Sciences, Harvard University,Cambridge, MA 02138, USA. Harvard is an equalopportunity/affirmative action employer.

Position Available



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SCEC Scientists' Submissions and Research Abstracts

SCEC Quarterly Newsletter Now Highlights Recent Publications/Submissions

In each issue, the SQN highlights recent publications of SCEC scientists and also provides more in-depth information such as abstracts orinterviews with authors. We also provide a complete bibliographical listing of SCEC research publications in the spring issue each year (seefollowing pages).

All papers that are the result of SCEC-funded research must be included in the database, and should list the "SCEC Contribution Number" in theacknowledgements section. To be added to the database, and receive the contribution number in return, simply email or fax Mark Benthien,SCEC Outreach Specialist (contact information below), with the following: authors, title, publication name and any other bibliographic informa-tion that is known. If possible, also include the text of the paper's abstract or introduction. This will greatly improve the function of the SCECdatabase, allowing for key word searches in both the title and abstract of all papers. Please do this before submitting a paper, in order to facilitateassignment of the SCEC contribution number. This database will soon be available on the Internet at SCEC’s home page:

www.scec.orgPlease support both new projects by emailing or faxing both past (if readily available) and future abstracts of your SCEC-funded publications.

Mark Benthien, Outreach Specialist email: [email protected] California Earthquake Center tel (213)-740-0323University of Southern California fax (213)-740-0011Los Angeles, CA 90089-0742

The SCEC Quarterly Newsletter seeks contributions from SCEC research-ers. Short summaries of current work in progress by researchers in theeight SCEC working groups will be published each issue. Please followthese guidelines:

Your contribution must be a project which falls into one of the eightworking groups:

Group A, Master Model: David Jackson, group leader

Group B, Ground Motion Modeling: Steve Day, group leader

Group C, Earthquake Geology: Kerry Sieh, group leader

Group D, Subsurface Imaging and Tectonics: Rob Clayton, group leader

Group E, Crustal Deformation: Ken Hudnut, group leader

Group F, Regional Seismicity and Source Processes: Egill Hauksson,group leader (will be combined with Group D)

Group G, Physics of the Earthquake Source: Leon Knopoff, group leader

Group H, Engineering Applications: Geoff Martin, group leader

The length of the article should be about 500-750 words of text, written ata 4-year (Bachelor’s) college degree level. If you use technical phrases orjargon, please include brief definitions. (Although our readers are well-educated experts, they are likely not up to speed in your earth-science orengineering-related field; definitions help.) The text should cover adescription of your research project and how it fits with the workinggroup's goals; names of principal investigators, post-docs, graduate orundergraduate students; and the important findings. If you would like toinclude figures, graphs, or photos, we can incorporate them into thearticle. We can either scan in original figures or photos, or receive themfrom you via the Internet. For information on how to best transfer yourfigures or photos, contact Mark Benthien at [email protected].

SQN Seeks Contributions from Scientists

See “Abstracts" on Page 18

367. Kagan, Y. Y., “Are Earthquakes Predictable?” GeophysicalJournal International, submitted, 1997.

The answer depends on the definition of earthquakeprediction. We discuss several definitions and possibleclassifications of earthquake prediction methods. We alsoconsider various measures of prediction efficiency, reviewseveral recent examples of earthquake prediction, anddescribe the methods that can be used to verify predictionschemes. We conclude that an empirical search forearthquake precursors that forecast the size of animpending earthquake has been fruitless. Reported cases ofprecursors can be explained by random noise or by acoincidence. We present evidence that earthquakes arenonlinear, chaotic, scale-invariant phenomena. The mostprobable consequence of earthquake similarity is lack ofearthquake predictability as it is popularly defined—i.e., aforecast of a specific individual earthquake. Many smallearthquakes occur throughout any seismic zone,demonstrating that the critical conditions for earthquakenucleation are satisfied almost everywhere; apparently, anysmall shock can grow into a large event. Thus, it is likelythat an earthquake has no preparatory stage. This skepticalview of current earthquake prediction efforts should not beinterpreted as a statement of the futility of any furtherattempts to mitigate the destructive effects of earthquakes.The seismic moment conservation principle, combinedwith geodetic deformation data, offers a new way toevaluate the seismic hazard, not only for tectonic plateboundaries, but for areas of low seismicity—e.g., the

Abstracts of Recent Publications

Below are the abstracts that have been submitted for recentlypublished SCEC publications. The numbers are the SCECpublication number. See the full publication list on the oppositepage.



SCEC Research Publications

365. Ben-Zion, Y., Dynamic simulations of slip on a smooth fault in anelastic solid, Journal of Geophysical Research, in press, 1997.

366. Souter, B. J., and B. H. Hager, Fault propagation fold growth duringthe 1994 Northridge, California, earthquake, Journal of GeophysicalResearch, in press, 1997.

367. Kagan, Y. Y., Are earthquakes predictable? Geophysical JournalInternational, submitted, 1997.

368. Kohler, M. D., J. E. Vidale and P. M. Davis, Lowermost mantlescattering from dense array waveforms, AGU Geophysical Monographon the Core-Mantle Boundary Region, M. Gurnis, M. Wysession, E.Knittle and B. Buffett, eds., submitted, 1997.

369. Sornette, D., and L. Knopoff, The paradox of the expected time untilthe next earthquake, Bulletin of the Seismological Society of America, inpress, 1997.

370. Hardebeck, J. L., J. J. Norris and E. Hauksson, Quantitativeobservations of static stress change triggering in two southernCalifornia aftershock sequences, Journal of Geophysical Research,submitted, 1997.

371. Eneva, M., and Y. Ben-Zion, Techniques and parameters to analyzeseismicity patterns associated with large earthquakes, Journal ofGeophysical Research, in press, 1997.

372. Eneva, M., and Y. Ben-Zion, Application of pattern recognitiontechniques to earthquake catalogs generated by models of segmentedfault systems in three-dimensional elastic solids, Journal of GeophysicalResearch, in press, 1997.

373. Lyakhovsky, V., Y. Ben-Zion and A. Agnon, Distributed damage,faulting, and friction, Journal of Geophysical Research, submitted, 1997.

374. Day, S. M., G. Yu and D. J. Wald, Dynamic stress changes duringearthquake rupture, Bulletin of the Seismological Society of America,submitted, 1997.

375. ten Brink, U. S., R. M. Drury, G. K. Miller, T. M. Brocher and D. A.Okaya, Los Angeles Region Seismic Experiment (LARSE), Californiaoff shore seismic refraction data, USGS Open File Report 96-27, 1996.

376. Fuis, G. S., J. M. Nurphy, W. J . Lutter, T. E. Moore, K. J. Bird and N. I.Christensen, Deep seismic structure and tectonics of northern Alaska:crustal-scale duplexing with deformation extending into the uppermantle, Journal of Geophysical Research, in press, 1996.

377. Ryberg, T., and G. S. Fuis, A master decollement beneath the SanGabriel Mountains and northern Los Angeles basin: evidence fromLARSE of a bright reflective zone, Tectonics, submitted, 1996.

378. Ward, S., Dogtails and rainbows: synthetic earthquake rupturemodels as an aid in interpreting geological data, Bulletin of theSeismological Society of America, accepted, 1997.

379. Spotila, J. A., K. A. Farley and K. Sieh, The exhumation and uplifthistory of the San Bernardino Mountains along the San Andreasfault, California, constrained by radiogenic heliumthermochronometry, Tectonics, submitted, 1997.

380. Dolan, J. F., and T. L. Pratt, High-resolution seismic reflectionprofiling of the Santa Monica Fault Zone, West Los Angeles,California, Seismological Research Letters, in press, 1997.

381. Wen, L. X., Helmberger and V. Donald, Propagational corrections forbasin structure: Landers earthquake, Bulletin of the SeismologicalSociety of America, 87, no. 4, pp. 782–787, 1997.

382. Bock, Y., M. Van Domselaar, S. Williams, P. Fang, and K. Hudnut,Southern California permanent GPS geodetic array: continuous

measurements of crustal deformation in the Los Angeles basinbetween the 1992 Landers and 1994 Northridge earthquakes,Northridge Earthquake Research Conference, CUREe, submitted, 1997.

383. Olsen, K., R. Madariaga and R. Archuleta, Three-dimensionaldynamic simulation of the 1992 Landers earthquake, Science,submitted, 1997.

384. Madariaga, R., K. Olsen and R. Archuleta, Modeling dynamicrupture in a 3-D earthquake fault model, Bulletin of the SeismologicalSociety of America, submitted, 1997.

385. Stirling, M. W., and S. G. Wesnousky, Comparison of recentprobabilistic seismic hazard maps for southern California, Bulletin ofthe Seismological Society of America, submitted, 1997.

386. Zhao, D., Y. Xu, D. Wiens, L. Dorman, J. Hildebrand, and S. Webb,Depth extent of the Lau back-arc spreading center and itsrelationship to subduction processes, Science, submitted, 1997.

387. Tsutsumi, H. and R. S. Yeats, Geologic setting of the 1971 SanFernando and 1994 Northridge earthquakes in the San FernandoValley, California, Journal of Geophysical Research, submitted, 1997.

388. Geiser, P., and L. Seeber, Three-dimensional seismo-tectonic imagingin the central Transverse Ranges, Journal of Structural Geology, inpreparation, 1997.

Alphabetical Cross-ReferenceThe recent publications are cited in full by SCEC publicationnumber. The list below is an alphabetical list of main authorsshowing corresponding publication numbers to help youfind a particular author’s work in the numerical list.

Ben-Zion, Y. .................................... 365Bock, Y. and others ....................... 382ten Brink, U. S. and others ........... 375Day, S. M. and others .................... 374Dolan, J. F. and others .................. 380Eneva, M. and others .................... 371Eneva, M. and others .................... 372Fuis, G. S. and others .................... 376Geiser, P. and others ..................... 388Hardebeck, J. L. and others ......... 370Kagan, Y. Y. .................................... 367Kohler, M. D. and others .............. 368Lyakhovsky, V. and others ........... 373Madariaga, R. and others ............ 384Olsen, K. and others ..................... 383Ryberg, T. and others ................... 377Sornette, D. and others ................. 369Souter, B. J. and others ................. 366Spotila, J. A. and others ................ 379Stirling, M. W. and others ............ 385Tsutsumi, H. and others ............... 387Ward, S. .......................................... 378Wen, L. X. and others ................... 381Zhao, D. and others ...................... 386



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interior of continents. Earthquake clustering with thepower-law temporal decay (Omori’s law) can be used toestimate the rate of future earthquake occurrence. The real-time seismology can facilitate relief efforts after largeearthquakes and eventually provide an immediatewarning about strong earthquakes a few seconds or tens ofseconds before the shaking starts.

374. Day, S. M., G. Yu, and D. J. Wald, “Dynamic StressChanges during Earthquake Rupture,” Bulletin of theSeismological Society of America, submitted, 1997.

We assess two competing dynamic interpretations thathave been proposed for the short slip durationscharacteristic of kinematic earthquake models derived byinversion of earthquake waveform and geodetic data. Thefirst interpretation would require a fault constitutiverelationship in which rapid dynamic restrengthening of thefault surface occurs after passage of the rupture front, ahypothesized mechanical behavior that has been referredto as “self-healing.” The second interpretation wouldrequire sufficient spatial heterogeneity of stress drop topermit rapid equilibration of elastic stresses with theresidual dynamic friction level, a condition we refer to as“geometrical constraint.” These interpretations implycontrasting predictions for the time dependence of thefault-plane shear stresses. We compare these predictionswith dynamic shear stress changes for the 1992 Landers(M␣ 7.3), 1994 Northridge (M␣ 6.7), and 1995 Kobe (M␣ 6.9)earthquakes. Stress changes are computed from kinematicslip models of these earthquakes using a finite differencemethod. For each event, static stress drop is highly variablespatially, with high stress drop patches embedded in abackground of low, and largely negative, stress drop. Thetime histories of stress change show predominantlymonotonic stress change after passage of the rupture front,settling to a residual level, without significant evidence fordynamic restrengthening. The stress change at the rupturefront is usually gradual rather than abrupt, probablyreflecting the limited resolution inherent in the underlyingkinematic inversions. On the basis of this analysis, as wellas recent similar results obtained independently for theKobe and Morgan Hill earthquakes, we conclude that, atthe present time, the self-healing hypothesis is unnecessaryto explain earthquake kinematics.

378. Ward, S., “Dogtails and Rainbows: Synthetic EarthquakeRupture Models as an Aid in Interpreting GeologicalData,” Bulletin of the Seismological Society of America,accepted, 1997.

For decades geologists have been collecting informationfrom historical and paleoearthquakes that could contributeto the formulation of a “big picture” of the earthquakeengine. Observations of large earthquake ruptures,unfortunately, are always going to be spotty in space andtime, so the extent to which geological informationsucceeds in contributing to a grander view of earthquakesis going to be borne not only by the quantity and quality of

data collected, but also by the means by which it isinterpreted. This paper addresses the need to more fullyunderstand geological data through carefully tailoredcomputer simulations of fault ruptures. Dogtails andrainbows are two types of fault rupture terminations thatcan be recognized in the field and can be interpretedthrough these models. Rainbows are concave downruptures that indicate complete stress drop andcharacteristic slip. Rainbow terminations usually coincidewith fault ends or strong segment boundaries. Dogtails areconcave up ruptures that indicate incomplete stress drop orstress increase and noncharacteristic slip. Dogtailterminations can happen anywhere along a fault or faultsegment. The surface slip pattern of the M␣ 6.6, 1979Imperial Valley CA earthquake shows both dogtail andrainbow terminations. The rainbow confirms the presenceof a strong fault segment boundary 6 km north of theinternational border that had been suggested by Sieh(1996). The dogtail implies that the displacement observedin 1979 is not characteristic. By combining paleoseismicinformation with the surface slip patterns from this eventand the M␣ 7.1, 1940 Imperial Valley earthquake, aquantitative Imperial fault model was developed withnorthern, central, and southern segments possessing 50,110, and 50 bar strength and 28, 13, and 22 km lengthrespectively. Both the 1940 and 1979 events showed 1-mamplitude dogtailed ruptures of the northern segment;however, characteristic slip of the segment is more likely tobe about 3 m. To illustrate the full spectrum of potentialrupture modes, models were run forward in time togenerate a 2000-year rupture “encyclopedia.” Although thesegmentation and strength of the Imperial fault are wellconstrained, modest changes in two friction lawparameters produce several plausible histories. Furtherdiscrimination awaits analysis of the extensivepaleoseismic record that geologists believe exists in theshore deposits of the intermittent lakes of the SaltonTrough.

382. Bock, Y., M. Van Domselaar, S. Williams, P. Fang, and K.Hudnut, “Southern California Permanent GPS GeodeticArray: Continuous Measurements of CrustalDeformation in the Los Angeles Basin between the 1992Landers and 1994 Northridge Earthquakes,” NorthridgeEarthquake Research Conference, CUREe, submitted, 1997.

We investigate the time series of daily positions estimatedfor two continuously global positioning system (GPS) sitesin the Los Angeles region in the 19-month period betweenthe 1992 Landers and 1994 Northridge earthquakes. Thesite at the Jet Propulsion Laboratory in Pasadena (JPLM)was active throughout the 19-month period; the site on thePalos Verdes Peninsula (PVEP) was activated only 9months before the Northridge earthquake. A comparison ofthe post-Landers site velocities with those derived GPS andvery long baseline interferometry measurements collectedover 5–8 years prior to the earthquake indicate a significantchange in the displacement rate at JPLM. The velocitydifference after the Landers earthquake is manifested

Abstracts continued from Page 16 . . .



primarily as a decrease in magnitude of about 2 mm/yr ina direction nearly coincident with the direction ofcoseismic surface displacement. Since the same pattern ofdeformation is observed over a wide aperture in southernCalifornia, we infer that the entire Los Angeles basinexperienced postseismic deformation in order of 1–2 mm/yr in the 19-month period preceding the Northridgeearthquake. By analyzing the coseismic and postseismicdisplacements at the JPLM and PVEP sites, we infer (1) anincrease in the contraction rate of the Los Angeles basinafter the Landers earthquake, which is relieved by theNorthridge earthquake; and (2) a possible role for theLanders earthquake in triggering the Northridgeearthquake.

385. Stirling, M. W., and S. G. Wesnousky, “Comparison ofRecent Probabilistic Seismic Hazard Maps for SouthernCalifornia,” Bulletin of the Seismological Society of America,submitted, 1997.

Probabilistic seismic hazard (PSH) maps for southernCalifornia produced from the models of Ward (1994), theWorking Group on California Earthquake Probabilities(1995), and the U.S. Geological Survey and CaliforniaDivision of Mines and Geology (Petersen and others, 1996)show the peak ground accelerations predicted with eachmodel to occur at 10% probability in 50 years and theprobability that 0.2g will occur in 30 years for “rock” siteconditions. Differences between the maps range up to 0.5gand 50%, respectively. We examine the locations andmagnitudes of the differences as a basis to define the issuesand avenues of research that may lead to more confidentestimates of PSH in the future. Our analysis shows thatcontrasting assumptions bearing on the proportion ofpredicted earthquakes that are distributed off the majormapped faults, the size of the maximum magnitudeassigned to a given fault, the use (or not) of geodetic straindata to calculate earthquake rates, and the choice ofground motion attenuation relation each contribute to theobserved differences between the maps.

SCEC-Sponsored Science Seminar &Workshop on Sediment Nonlinearity

When:Seminar: Jan. 29, 1998 (afternoon)Workshop: Jan. 30, 1998

Where: USC

Organized by: Ned Field ([email protected])

Description:It has been understood for more than 100 years that sedimentscan increase the level of earthquake ground motion relative tobedrock. However, there has been a long-standing and oftencontentious debate between seismologists and engineers onwhether the response of sediments to strong ground motion issimilar to that of relatively well-studied weak motion. Theprevailing view in the engineering community, based almostexclusively on laboratory studies, is that sediments respondnonlinearly. That is, amplification factors are generally reducedfor stronger ground motion because the finite strength ofsediments causes a breakdown of Hooke’s law. This perspectivehas been applied in engineering practice. Seismologists, on theother hand, have traditionally been skeptical because of a lack ofevidence and a skepticism that laboratory studies represent insitu behavior. They’ve generally concluded that either sedimentnonlinearity is insignificant or that it is buried among themyriad of other complicating factors (i.e., uncertainties) in thedata. Recent progress in several disciplines makes the time ripefor a seminar and workshop on this problem.

At the seminar (afternoon of Jan. 29, 1998), representatives fromeach discipline will give overview talks on the following topics:

• Lab-based studies of sediment response conducted by theengineering community

• How engineers use these results to theoretically modelsediment response

• Seismological evidence for and against sediment nonlinearity

• The view from the rock-mechanics/physics community

• What’s applied in the building codes

The purpose of this seminar is to educate the general SCECcommunity and to bring the members from the various disci-plines up to speed about the other disciplines.

With this introduction, the workshop on the next day will focuson specific technical issues that remain unresolved. Participantswill be invited to present and discuss results that pertain tothese issues. Given the unprecedented diversity of disciplinesthat will be in attendance, it is hoped that this workshop willestablish points of agreement and disagreement, stimulatecrossbreeding, and identify priorities for future research.

If you are interested in participating in the workshop, pleasecontact Ned Field (213-740-7088; [email protected]) to let him know.Please also include your thoughts on what issues should beaddressed at the workshop.

386. Zhao, D., Y. Xu, D. Wiens, L. Dorman, J. Hildebrand, andS. Webb, “Depth Extent of the Lau Back-Arc SpreadingCenter and Its Relationship to Subduction Processes,“Science, submitted, 1997.

Seismic tomography and waveform inversion reveal thatvery slow velocity anomalies (5–7%) beneath the activeLau spreading center extend to 100 km depth and areconnected to slow anomalies (2–4%) in the mantle wedgeto 400 km depth. This indicates that geodynamic systemsassociated with back-arc spreading are related to deepprocesses, such as the convective circulation in the mantlewedge and deep dehydration reactions in the subductingslab. The slowest anomalies exist just west of the Lauspreading center, consistent with the observation thatcurrent ridge propagation processes are moving thespreading center away from the Tonga arc.



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Knowledge Transfer continued from Page 5 . . .

Southern California museums are also targeted by SCEC, whichhas developed a series of prototype mechanical exhibits thatinform the public about natural hazards and earthquake engineer-ing concepts and practices.

State Mitigation PlanOur involvement in the earthquake safety community and theeffects of our work go beyond our southern California borders.Representing SCEC and the knowledge transfer community ingeneral, I served during 1996-1997 as a member of the writingteam in the area of education and information dissemination forthe state’s earthquake hazard mitigation plan. A Seismic SafetyCommission publication, the California Earthquake Loss ReductionPlan, should be off the presses this fall. Besides being required byFEMA before the release of any mitigation money, FEMA plans touse this plan as a model for other states. We developed initiativesfor legislation to set licensing and competency requirements forpracticing professionals; short courses and other means toincrease the level of understanding among the media and thepublic; workshops for state, city, and county officials on vulner-ability assessment and loss reduction measures; and the establish-ment of a statewide K-12 earthquake education program.

Our work with the Seismic Safety Commission, the CaliforniaDivision of Mines and Geology, and the City of Los Angeles hashelped strengthen the resolve of public officials to improvemitigation strategies. Earthquake scenarios now under develop-ment (for the Phase III report) will provide much more realisticestimates of expected ground shaking in the metropolitan areas ofsouthern California. The probabilistic hazard assessment methodsand earthquake scenarios being developed for southern Californiacan be transferred nationwide. Already they are beginning to beemulated in northern California and in the Pacific Northwest.

Key PublicationsFinally, a couple of other publications deserve mention. Our mostsuccessful endeavor to date has been a public awareness booklet.

In 1994-95, we developed and produced two million copies ofPutting Down Roots in Earthquake Country, a 32-page, full-colornontechnical version of thePhase II report. The booklet wasdirected to a diverse audienceof disaster preparedness andresponse personnel, city andcounty officials, engineers andplanners, the general public,and the media. Two-thirds ofthe booklets were distributedthrough all 12 of southernCalifornia’s county publiclibrary systems; the rest,through the SCEC office. Weare now negotiating a reprintof the booklet, adding aSpanish language version, inpartnership with a localtelevision station.

And if you’re reading this article, you know about our SCECQuarterly Newsletter. We feature ongoing research and activitiessponsored by the Center, and include in each issue a list of thelatest Center publications. We publish scientific and technicalarticles written by SCEC scientists, researchers, and staff andglean interesting information and articles from other organiza-tions emphasizing research on earthquake phenomena. Readersinclude representatives of the U.S. government; California state,county, and city government agencies; business and industryleaders interested in earthquake hazard mitigation; academicinstitutions, including pre-college teachers and students; themedia; and the general public.

Where Do We Go from Here?Plans for the next five years include media-related activities thatpromote awareness and loss reduction, such as the “L.A. Under-ground” radio spot series with KFWB Radio Anchor Jack Popejoy.As part of the second printing of Putting Down Roots, KTLATelevision will be launching its own television spots or vignettesthat encourage earthquake preparedness.

Partnerships with the media will be fundamental to getting outour message. One of our baseline efforts will be a guide for themedia themselves, providing them with basic information,contacts, and guidelines related to earthquake preparation andresponse. In the coming months, we will plan a workshop toproduce a media information guidebook, special Web site, andfield training series.

The Phase III version for practicing professionals, authored byEdward Field, a SCEC research scientist at USC, will be availablesoon. We also plan to feature the newest research on groundmotion scenarios in future versions of Putting Down Roots. Ofcourse, Web surfers will see us continue to promote product usageand data dissemination via the SCEC Web pages and links, theSCEC infrastructure facilities, and the online databases.

USC Seeking Student Researchers

The geophysics group at the University of SouthernCalifornia is looking for outstanding graduate students andpostdoctoral fellows to participate in a variety of vigorousresearch programs on earthquake physics, crustaldynamics, and waveform seismology. For moreinformation on the geophysics program, visit the USC website at HTTP://WWW.USC.EDU/DEPT/EARTH. For information onavailable opportunities and application procedure, contactProf. Sammis ([email protected]).



PUBLICATIONS

Putting Down Roots in Earthquake Country 32-page, full-color nontechnical overview of earthquake probabilities,risks, and preparation.

SCEC Quarterly Newsletter Ongoing Center research and activities, lists of Center, scientific andtechnical articles by SCEC scientists, researchers, and staff, andinteresting information from related organizations.

Phase I Report : Future Seismic Hazards in Southern First stage of a comprehensive assessment of the earthquake risk inCalifornia, Phase I: Implications of the 1992 Landers southern California; discusses the recent increase in the frequency ofEarthquake Sequence earthquakes in southern California, makes several recommendations for

further study.Phase II Report: Seismic Hazards in Southern California: Second stage of our overall assessment of the earthquake risk, giving theProbable Earthquakes, 1994-2024 probability of earthquake shaking strong enough to cause moderate

damage, specifically predicting 80- 90% probability of an earthquake M 7+before 2024.

Phase III Report: [in preparation] Builds on Phase II; includes source effect, site conditions, propagationpath effect on strong ground motion. Two-part report will contain sampleprobabilistic seismic hazard maps and consensus time histories forselected earthquake scenarios and sites in southern California.

KFWB Radio Anchor Jack Popejoy “L.A. Underground” radio spots One of several media-related activities to promote awareness and lossreduction.

WWW.SCEC.ORG World Wide Web site containing access to organizational information,data, and links to related topics and organizations.

WORKSHOPSUSGS, CDMG, SCESA, OES, Caltech Making the Most of New Real-Time Information Comparisons of hardware, software, and data disclaimers.

Technologies in Managing Earthquake EmergenciesOES One Year after Northridge Overall reassessment and update by all involved disciplines.IASPEI Educating the Public about Earthquake Hazards and Risks One-day workshop we led at the general assembly of IASPEI in Greece;

future workshops planned.Insurance industry Insurance vulnerability workshops Evaluation and upgrading of current methods used by the insurance

industry in measuring exposure.CDMG Zones of Deformation To provide advice to CDMG about establishing guidelines for the

delineation, evaluation, and mitigation of zones of deformation.ONGOING PROJECTS

CUREe PEER New alliance to support the outreach efforts of the proposed Pacificearthquake engineering research center.

CUREe Earthquake Hazard Mitigation of Woodframe Construction 3-year project covering all aspects of woodframe construction, includingeducation and training.

SEAOSC, City of L.A. Ground Motion Joint Task Force To study vulnerable structures in southern California.EERI, OES Post-Earthquake Technical Clearinghouse Actively involved with the Hardware and Archiving and Distribution

working groups.EERI, NCEER, Earthquake Information Providers Network To keep the emergency planning and response communities informed.SSC, NISEE /EERC (UCB),NISEE/Caltech, NHRAICNISEE/Caltech Library loan agreement For exchange of materials and library assistance to end users.AEG AEG Fault & Fold Database To aid the Association of Engineering Geologists in creating a fault and

fold database.SSC California Earthquake Loss Reduction Plan Participation on the writing team in the area of education and information

dissemination for the state’s earthquake hazard mitigation plan.PLANNED

KTLA TV Second printing of Putting Down Roots Television spots or vignettes that encourage earthquake preparedness &newest research on ground motion scenarios.

OES; USGS; all media Media information guidebook To provide media with basic information, contacts, and guidelines relatedto earthquake preparation and response.

Edward Field Phase III report, “nontechnical” version Version for practicing professionals who may use portions of the reportto aid in the design of new structures in seismically active areas.

FEMA; Ground Motion Joint Task Force Two booklets To increase public awareness of the hazards of vulnerable structure types.WSSPC 1998 Conference on Hazard Insurance Policy To help formulate and act on a national all-hazard approach to address

this critical issue.

IASPEI = International Association of Seismology and Physics of the Earth’s InteriorNHRAIC= Natural Hazards Research & Applications Information Center

Highlights of Knowledge Transfer Projects

Partner Project Description

SCESA= Southern California Emergency Services AssociationWSSPC = Western States Seismic Policy Council



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Southern California Earthquake Center Knowledge Transfer Program

The SCEC administration actively encourages collaboration amongscientists, government officials, and industry. Users of SCEC scientificproducts (reports, newsletters, education curricula, databases, maps, etc.)include disaster preparedness officials, practicing design professionals,policy makers, business communities and industries, local, state andfederal government agencies, the media, and the general public.

Knowledge transfer activities consist of end user forums and workshops,discussions among groups of end users and center scientists, writtendocumentation and publication of such interactions, and coordination ofthe development of end user-compatible products.

Planned and in-progress products and projects include:

• Insurance industry workshops; proceedings; audio tapes

• Engineering geologists’ workshops; proceedings; geotechnicalcatalog.

• Vulnerability workshops, city and county officials

• Media workshops

• Field trips

• Quarterly newsletter

• Putting Down Roots in Earthquake Country handbook

• SCEC WWW pages (WWW.SCEC.ORG)

• SCEC-sponsored publications; scientific reports

For more information onthe SCEC Knowledge Transfer Program, contact

Jill Andrews, Director, Knowledge Transferphone 213/740-3459 or email [email protected]

orMark Benthien, Outreach Specialist

phone 213/740-0323 or e-mail [email protected].

OFF-SCALER E A D I N G S F R O M A U T H O R S W H O A R E N O T E A R T H S C I E N T I S T S B U T W I S H T H E Y W E R E

“There is something fascinating about science.One gets such wholesale returns of conjecture out of such a

trifling investment of fact.”

Now, if I wanted to be one of those ponderous scientific people, and ‘leton’ to prove what had occurred in the remote past by what had occurredin a given time in the recent past, or what will occur in the far future by

what has occurred in late years, what an opportunity is here [the MississippiRiver]!

In the space of 176 years the Lower Mississippi has shortened itself 242 miles.That is an average of a trifle over one mile and a third per year. Therefore, anycalm person, who is not blind or idiotic, can see that in the Old Oolitic SilurianPeriod, just a million years ago next November, the Lower Mississippi River wasupwards of 1,300,000 miles long, and stuck out over the Gulf of Mexico like afishing-rod. And by the same token any person can see that 742 years from nowthe Lower Mississippi will be only a mile and three-quarters long, and Cairo andNew Orleans will have joined their streets together, and be plodding comfortablyalong under a single mayor and a mutual board of aldermen. There is somethingfascinating about science. One gets such wholesale returns of conjecture out ofsuch a trifling investment of fact.

Mark TwainLife on the Mississippi



El Molino Viejo (the Old Mill), an adobe structure built right at the base of the Raymond fault scarparound 1808, is evidence that the Raymond fault has not had any surface rupture in almost 200 years.This view is to the NNW; the vegetated fault scarp is to the left and behind the Old Mill.

Raymond Fault continued from Page 7 . . .

Raymond Fault ReferencesBuwalda, J. P. 1940. Geology of the Raymond basin: report to Pasadena water

department.

Conkling, H. 1929. San Gabriel investigation, analysis and conclusions. Division ofWater Rights Bulletin no. 7. San Gabriel Department of Public Works.

Dolan, J. F.; Sieh, K.; Rockwell, T. K.; Guptill, P.; and Miller, G. 1997. Activetectonics, paleoseismology, and seismic hazards of the Hollywood fault,northern Los Angeles basin, California. Geological Society of AmericaBulletin (in press).

Crook, R., Jr.; Allen, C. R.; Kamb, B.; Payne, C. M.; and Proctor, R. J. 1987.Quaternary geology and seismic hazard of the Sierra Madre and associatedfaults, western San Gabriel Mountains. U.S. Geological Survey ProfessionalPaper 1339, pp. 27–63.

Jones, L. M.; Sieh, K. E.; Hauksson, E.; and Hutton, L. K. 1990. The 3 December1988 Pasadena earthquake: evidence for strike-slip motion on the Raymondfault. Bulletin of the Seismological Society of America 80:474–482.

Weber, F. H., and others 1980. Earthquake hazards associated with the Verdugo-Eagle Rock and Benedict Canyon fault zones, Los Angeles County,California. California Division of Mines and Geology Open File Report 80-10LA. photos by Jill Andrews

“Before and After” shots of Lacy Park. The larger photo, circa 1900, is a view to the south overlooking Wilson Lake, a sag pond on the Raymond fault (courtesy of the San Marino Historic Society). The view in theinset is the same area today. View is to the south and west. Most of the park is located on the fault zone, at the base of the scarp. It is no longer possible to take exactly the same shot as the turn of the centuryphoto: trees now block that vista.

photo courtesy San Marino Historic Society



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It Roared “Like a Dragon”As aftershocks shook the region, tens of thousands of survivorsslept shivering in near-freezing temperatures in the streets outsidetheir homes, many without blankets. Most of the severe damageoccurred in poor villages in a 60-mile region roughly parallellingthe Afghan border in the far eastern side of central Iran. Reliefworkers and researchers said that the air in these villages wasrank with the smell of death.

More than 2,500 people died—most of them buried alive in mudhuts. Approximately 5,000 people were injured, and 100,000 lefthomeless. In Ardakul more than 100 children were killed at oncewhen a schoolhouse collapsed. One despondent patriarch had lostall six of his grandchildren to the school’s collapse. Altogether,almost a third of that village’s 1,600 residents perished.

The land “roared like a dragon,” say survivors of the 10 May 1997M 7.1 earthquake that struck at 12:28 PM on the Abiz fault ineastern Iran., They also say that day turned to night as thickclouds of dust blotted out the sun in Khorassan province.

The government put a cost of $100 million on damage caused bythe earthquake, which was the most devastating event to strikeIran since two earthquakes shook the provinces of Gilan andZanjan on June 21, 1990. Approximately 50,000 people were killedand 60,000 inured in those quakes, which had magnitudes of 7.3and 7.7, respectively.

Following the May 10 Abiz earthquake, the Iranian governmentpromised to pay $167 to every person who lost a relative.

Michael R. Forrest

M 7.1—80 Km of New RuptureA field team including Manuel Berberian (Najarian and Associ-ates) and Manushehr Ghorashi (Geological Survey of Iran) wasable to visit the site of the 1997 earthquake on the Abiz fault inKhorassan province in eastern Iran, near the Afghan border. Theearthquake produced more than 80 km of new surface rupture(right-lateral, strike-slip) on the fault, which strikes about N-S. Upto 195 cm of right-lateral offset was measured.

The Abiz fault previously ruptured during an Ms 6.6 earthquakeon November 14, 1979, with 17 to 35 km of surface rupture andright lateral displacement of up to 100 cm. It has not yet beendetermined whether the 1979 and 1997 earthquakes ruptured thesame source, although at least some parts of the fault wereruptured in both events.

The 33-km depth widely reported for the earthquake is ateleseismic default depth. In actuality, it was a crustal earthquakewith focal depth probably between 10 and 20 km. The Abiz faultcan be visualized on Fig. 10-27, p. 323 of the Geology of Earthquakes(the Kerry Sieh text), located at about 34N, 60E. It is part of acomplex array of faults with historical surface rupture startingwith the Dasht-e-Bayaz left lateral fault in 1968. The 1997 earth-quake appears to be part of a sequence starting with Dasht-e-Bayaz in 1968.

L. A. and Tehran: Sister Cities?Because of similar local tectonic styles, an interesting—if at firstglance unlikely—comparison can be made between greater LosAngeles and Tehran. Tehran is like the Los Angeles basin: a hugepopulation living in a plain that features range-front activereverse faults to the north and some active reverse faults in thebasin itself. Khorassan has a thick-skinned reverse fault provincesoutheast of the Dasht-e-Bayaz region, which produced a M 7.7reverse-fault earthquake at Tabas in 1978. Los Angeles has thethick-skinned Transverse Ranges. Iran, however, has 4,000 yearsof recorded history, with numerous nearby examples of earth-quakes of M 7 to M 7.5 in settings similar to those in southernCalifornia.

This suggests that the two M 6.7s the Los Angeles area has had inthe last 200 years do not represent the size of earthquake we needto be worried about—and planning for.

Bob Yeats, Manuel Berberian, and Manushehr Ghorashi.

Tectonic framework of Zagros and Pamir-Hindukush regions (Mohan and Rai, 1995).

Three Views of the 10 May

The People The Earthquake

The Global View . . .



Tectonic Framework of Eastern IranThe Afro-Arabian plate is subducting beneath much of Iran andAfghanistan along the Zagros thrust and the Makran arc-trenchsystem. Continental convergence between these two plates istaken up by distributed deformation in Iran, including folding,complex block rotations, and the associated slip on faults such asthe Abiz fault.

Along the central and eastern part of the Iranian Plateau, thetectonics are dominated to the north by E-W left-lateral and thrustfaults. South of these faults, subordinate N-S right-lateral strike-slip faults can be found that do not cross the northerly faults, aswell as thrust faults trending NW-SE. Movement on all thesefaults facilitates the squeezing of the eastern Iranian plateauagainst the stable blocks of western Afghanistan.

Iran was originally part of the great Arabian shield during thePaleozoic and was separated from Asia by a proto-Tethys sea. Theproto-Tethys closed, and the Iranian microplate was formed whenrifting occurred along the Zagros thrust zone at the end of thePaleozoic or in the early Mesozoic. A Neo-Tethys sea opened tothe south at that time and eventually closed again in the lateCretaceous as a result of northward drift of the Afro-Arabianplate. Continued convergence initiated a Himalayan-typecollision and consequent crustal thickening along the Zagrosthrust in the Late Miocene, a process that continues now.

Michael R. Forrest

Tectonic maps of Iran, The abbreviations stand for the following faults: NAF—NorthAnatolian, EAF—East Anatolian, MZT—Main Zagros, Na—Naiin, Kb—Kuh-Banan,Ny—Nayband, Do—Doruneh and Kz—Kazerun. The two arrows show the Arabia-Eurasia convergence velocity. The arrow in the southern Zagros corresponds to 35 mm/yr. (Sobouti and Arkani-Hamed, 1996)

1997 Earthquake at Abiz, Iran

The Geology

References

Mohan, G., and Rai, S. S. 1995. Large-scale three-dimensional seismictomography of the Zagros and Pamir-Hindukush regions.Tectonophysics 242, 255–265.

Sobouti, F., and Arkani-Hamed, J. 1996. Numerical modeling of thedeformation of the Iranian plateau, Geophys. Journ. Int, 126:805–812.



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Paleoseismology in the Cocos-Nazca-Caribbean Triple Junction

Hugh Cowan, Coordinator of Neotectonic Studies CEPREDENACProgram Central America

Since the late 1980s, six countries have participated in a regionalprogram to reduce the impact of natural disasters in CentralAmerica. The goal of the program is to avert future suffering andeconomic losses such as those caused by earthquakes in ElSalvador (1986), Guatemala (1976), and Nicaragua (1972).

The program was funded by Sweden under the auspices of theIDNDR (International Decade for Disaster Reduction). In the early1990s the program was expanded with contributions fromNorway (Seismic Instrumentation and Seismic Hazard Assess-ment) and Denmark (Flood Hazard Modeling). The first phase ofthe program concluded in 1994, and a second four-year phase(1996-99) began last year. The program is coordinated by Centrode Coodinacion para la Prevencion de los Desastres Naturales enAmerica Central (CEPREDENAC) on behalf of Guatemala, ElSalvador, Honduras, Nicaragua, Costa Rica, and Panama.

A modest but important new component of the program is theapplication of paleoseismology for hazard assessment of majoractive faults in Central America. The paleoseismology project ispresently linked to microzonation studies in selected urbancenters. The first field session was conducted in southern CostaRica, adjacent to the Panama border during April 1–15, 1997, as aprecursor to the seismic microzonation of David, the third city ofPanama (pop. 100,000).

intersection of the PFZ, at the supposed subduction interfaceoffshore, or beneath, Burica Peninsula.

However, discoveries in a study conducted in 1996 indicate thatthe PFZ extends farther north into the Costa Rica-Panamavolcanic arc than previously supposed (Cowan and others, inprep.). A spectacular surface trace has been mapped extendingunbroken for 15 km—from the swampy lowlands north of BuricaPeninsula to the foothills of the Cordillera Talamanca. A right-lateral offset of 1.3 km has been measured where the fault tracebisects the distal margin of a large alluvial fan of probable latePleistocene age. Smaller dextral offsets (4–65 m) are preserved atseveral streams and shutter ridges along the surface trace. At itsnorthern end the surface trace curves westward into a major east-west regional fault—the Longitudinal Fault Zone (LFZ) orBallena-Celmira Fault Zone. The proposed name for the newlyidentified structure is Canoas fault, after the adjacent border townof that name.

Context for the StudyPaleoseismic investigation of these large faults is important fordetermining the size and frequency of surface ruptures at theedge of the subducted Cocos plate and in the overlying forearccrustal wedge. These shallow seismic sources are of concern forthe city of David, located 50 km east of the international border,but within a few kilometers of the LFZ.

The LFZ has been recognized as a major geological structure sincethe 1960s, but no data have been available to constrain its sense ofmovement or late Quaternary slip rate. A better knowledge of therelationship between the LFZ and PFZ in the border region mayclarify whether the LFZ is presently active farther east in Panama,or whether it’s less active because of the siphoning of strainsouthward along the Canoas fault. In the 1996 study, no evidenceof Holocene displacement was documented along the LFZ inPanama, but abundant circumstantial evidence of Holoceneactivity is evident on the LFZ west of its intersection with theCanoas fault—for example, unweathered fault gouge zones andanomalous drainage patterns.

Better knowledge of the slip rates on the respective faults wouldalso improve existing seismological models of interplate couplingin this area and help clarify the cross-cutting relationshipsbetween the triple-junction elements.

Western Panama and Southern Costa RicaCosta Rica and Panama form a tectonically active junctionbetween four major lithospheric plates—Caribbean, Cocos, Nazca,and South America at the southern end of the Middle Americanvolcanic arc-trench system. Three of these plates—Cocos, Nazca,and Caribbean—interact beneath the Pacific margin of southernCosta Rica and western Panama, producing frequent earthquakes,including four events of M 7.5 or greater during this century.

Major structural elements of the triple-junction include the CocosRidge—a buoyant trace of the Galapagos hot-spot that forms partof the Cocos plate, presently being subducted beneath southernCosta Rica at a rate of 7–9 cm/yr. The eastern margin of the CocosRidge is truncated by the Panama Fracture Zone (PFZ), a highlyactive oceanic transform fault that accommodates 5–6 cm/yr. ofright-lateral strike-slip. The PFZ divides the Cocos and Nazcaplates north-south and intersects the Costa Rica-Panama arc atBurica Peninsula, the Pacific land border between Costa Rica andPanama.

Previous studies, notably by researchers from the University ofTexas, have identified elements of the PFZ extending onshorealong the axis of Burica Peninsula, then curving westward intothe strike of a fold-and-thrust belt, developed in Cretaceous-Quaternary forearc sediments above the subducted Cocos plateand its antecedents. The present location of the Cocos-Nazca-Caribbean triple junction has traditionally been depicted as the

FieldworkFieldwork spanned 15 consecutive days from April 1–15. Thenational team included Walter Montero and Guillermo Salazarfrom the Central American School of Geology, University of CostaRica, and Guillermo Alvarado and Fransisco Arias of InstitutoCostarricense de Electricidad.

Several of the potential trenching sites had been identified fromreconnaisance study last year. Locating an available backhoe wasmore difficult. With the onset of the rainy season imminent, mostcontractors were working frantically to complete their summerdrainage tasks. Paleoseismology seemed too fiddly....

We eventually located excellent machines and operators andsubsequently opened six trenches: four on the Canoas fault andtwo across the LFZ. We were lucky with the weather—no rain fell



during the two weeks. Conditions in the trenches were tough,however, with 100% humidity and a grinding heat. We managedto dig at least one trench adjacent to a deep river pool—repletewith waterfall and ripe mangos—but not every site was soblessed.

The evenings never failed to please. Toucans flew in to roostoverhead as we logged trench walls by half-light. Comet Hale-Bopp put on a good show following a flaming sunset, and thatwas followed by thousands of fireflies in the grass fields afterdark. Inevitably, we encountered characters in the countrysidewith always a spare moment to recount the folklorico of snakes,Indian relics, stony ground, artesian springs, and harder timespast. One old timer described precisely the location and extent ofthe (Canoas) fault—known to him for 20 years or more.

Preliminary Results—Canoas FaultAt its southern tip, the Canoas fault passes beneath late Holocenefluvial overbank deposits. We trenched the youngest expression ofthe fault, where sand and silt deposits are displaced across a smallsag pond. Two buried soils and associated colluvial wedgesshould help constrain the ultimate and penultimate ruptureevents. An unexpected bonus was the discovery of pumice andash horizons in this trench and two others farther north. Thesesediments probably correspond to eruptions from Volcan Baru, a3,470-m strato-volcano located in the Cordillera, 40 km north ofDavid, Panama.

In two other trenches on the PFZ, stratigraphic control appearsstrong for constraining the last event. Pre-Colombian artifacts(probably 500-1,500 yr B.P.) were recovered from four of the sixtrenches. In all cases, the horizons of human occupation werefaulted, and one site was possibly abandoned after the last eventdiverted an active stream channel.

Preliminary Results—LFZAt Rio Abrojo, 4 km east of Ciudad Neilly, Costa Rica, the LFZtruncates fluvial terraces 6-15 m above the modern floodplain.Terraces less than 6 m above the floodplain are not offset. Weexcavated one trench at the mid-slope of the highest section of thefault scarp (beneath the oldest terrace) and another on the flat10␣ m south of the scarp at an anomalous, left-lateral offset in twochannels whose source is a spring at the base of the fault scarp.

Regrettably, we had only one day in which to excavate thisimportant site because of local political difficulties. Furthermore,30 minutes into the excavation, the backhoe had a punctured tire;simultaneously its alternator burned out. Despite the constraintsimposed by this additional delay, we recovered importantinformation. A reverse fault was exposed beneath the main scarpand offsets in a thick sequence of silty colluvium were docu-mented, extending almost to the ground surface. Pre-Colombianartifacts and charcoal were recovered in the hanging-wall at-1.70␣ m, implying that the sedimentation rate has been high.

In the second trench south of the main scarp, a fault extended upinto a deformed silt layer 0.4 m below ground surface. The surfaceof the silt layer was associated with wood and large palm seeds,indicating a former ground surface. This surface was covered bycobbles and small boulders, consistent with rapid burial bylandsliding (there is no active stream channel). The debris was

overlain by sandy organic sediment. Projection of the fault to thesurface coincided with the offset wall of the stream channels.There was no evidence of more than one rupture event. Precisedating of the buried channel surface will, we hope, constrain thetiming of the last rupture. The offsets? Three measurements onthree channel margins: 7 m, 6.5 m, 5.5 m, all left-lateral.

ConclusionThe preliminary results of this work are encouraging. The LFZ isnow confirmed as an active structure and a major seismic sourcein Costa Rica. With direct evidence of the last event, we can hopeto constrain magnitude limits and clarify the kinematic modelspreviously based on ambiguous seismological (focal mechanism)data. The timing of two events on the Canoas fault seems feasible,and it is also possible that we can learn more about the timing oflate Holocene eruptions from Volcan Baru, Panama.

Each of the sites trenched in this study is situated adjacent to alarger volume of undisturbed terrain, so future studies may yieldadditional information about the rupture histories of these largefaults. Data from this field campaign will be presented shortly,together with related unpublished data gathered during the pasttwo years in this region.

The best initial source of information about the tectonics, regionalstructure, and unsolved problems of this fascinating region is theexcellent compilation of work in Geological Society of AmericaSpecial Paper 295, 1995 (P. Mann, Ed.).

Future Paleoseismology under CEPREDENACTentative planning has begun for a trenching study of normalfaults in the Managua Graben, Nicaragua, the site of the devastat-ing 1972, M 6.2 earthquake. If confirmed, the work will beconducted during the dry season (Jan.–April) of 1998 as a smallpart of a microzonation project presently underway in Managua.Naturally, there are more potential projects than either time orresources permit. I am keen to hear from people interested in theconcept of “joint-ventures” that would broaden the technicalinput and experience in paleoseismology studies under theCEPREDENAC program. A parallel goal within this program isthe transfer of experience to participating institutions throughoutthe region.

Because the paleoseismology component of the total program ismodest, it is not possible to offer financial support for salary ortravel to people outside the local participating institutions.However, the institutional relationships and local logisticalsupport provided by the CEPREDENAC program represent atangible benefit for any group or individual interested in this typeof work in Central America.

Addresses for Hugh Cowan: Instituto de Geociencias Universidadde Panama, Panama; [email protected]

Also available on the paleoseismology website (HTTP://GLDAGE.CR.USGS.GOV/PALEOSEI/PPFORUM.HTM):

“Paleoseismology along the Caribbean-North American PlateBoundary”

“Preliminary Geological Report on the Cariaco July 9, 1997,Earthquake, Sucre State, Northeastern Venezuela”



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Calendar

New Writer & Editor

SCEC Notes sively appropriate back-ground. He has previouslyworked in the area ofearthquake safety for thestate Seismic Safety Com-mission.

September24-27—Field Workshop onPaleoseismology of the SanAndreas Fault, Los AngelesHost: Kerry Sieh. Contact:[email protected]

30-Oct 3—AEG AnnualConvention, Portland, OR;520/204-1553

October2-3—3-D Modeling WorkshopL.A. area. Host: Norm Abrahm-son: [email protected]

5-7—SCEC Annual Meeting &Field Trip,Costa Mesa, CA(See agenda on page 31.)

5-8—Annual meeting, EasternSection of the SeismologicalSociety of America. Ottawa.Contact: G. Atkinson,[email protected]

15—SCEC San Andreas FaultField Trip for Media Representa-tives, led by Thomas Henyey, etal. Los Angeles, CA. Info: 213/740-1560.

20-23—Geological Society ofAmerica annual meeting, SaltLake City. Contact: 800-472-1988;email [email protected];http://www.geosociety.org/meetings/97/index.htm.

22-24—Using GIS for DisasterManagement: Domestic andInternational Applications,Madison, WI. Disaster Manage-ment Center, Univ. of Wisconsin-Madison. 800-462-0876;[email protected]

23-25—General EarthquakeModeling (GEM) Workshop. LosAlamos National Laboratory andothers, Santa Fe. [email protected]

24-25—SCEC Workshop: Computa-tional Methodologies for Simulat-ing Earthquakes. Santa Fe, NM.Hosts: John Rundle (UofCO,Boulder); Bernard Minster (Scripps,UCSD). 303/492-5642

NovemberTBD—City of Los AngelesVulnerability Workshop III

1-4—International Workshop onthe Vrancea Earthquake, Bucharest,Romania. [email protected] [email protected].

3-5—International Conference andSino-American Symposium on theTectonics of East Asia, Chungli,Taiwan. Contact: C.H. Lo,[email protected]

4-7—WSSPC Annual Conference,Victoria, British Columbia, Canada.Email [email protected]

6–8—Symposium on New Imagesof the Earth’s Interior ThroughLong-Term Ocean-Floor Observa-

writer and editor based inSacramento.

He will be working with theKnowledge Transfer Pro-gram staff at SCEC. Eventhough he will not have anoffice at SCEC, he will beintegrated into the team viaelectronic links since one ofhis specialties is long-distance desktop publish-ing.

tions, Chiba Prefecture, [email protected] (or [email protected])

10-14—Second Pan-AmericanSymposium on Landslides. Rio deJaneiro. [email protected].

17-19—12th International Confer-ence and Workshops on AppliedGeologic Remote Sensing.Environmental Research Inst. ofMich.. Denver. [email protected]

12, 3-6 pm—CLA/SEAOSC/SCECJTF full committee meeting,Davidson Hall.

December8-12—AGU Fall Meeting, SanFrancisco, CA. Contact:[email protected]

January 19986—NSF preproposal for new roundof STCs due.

16—San Cayetano Fault Field Trip.Ventura County, CA. Led by Dr.Thomas Rockwell, SDSU

27-28—Workshop with Los AlamosNational Lab, “Earthquakes andUrban Infrastructure”; LosAngeles. Contact: Grant Heiken(LANL), Jill Andrews

29-30—SCEC Science Seminar &Workshop on Sediment Nonlinear-ity. L.A. Ned Field: [email protected]

January—Shalheveht FreierInternational Workshop on

Congratulations from theSCEC community toProfessor Kei Aki andValerie Ferrazzini, whoannounced the birth oftheir daughter Uka, bornJuly 28, 1997. “Uka” is acombination of “U” for“Universe” and the Japa-nese word “Ka,” whichmeans “volcanic island.”Professor Aki and Valerielive on La Reunion Island,where he is conductingresearch and spending timewith his family.

Kei + Valerie = Uka

This month a new writerand editor begins work atSCEC. You’ve been lookingat his first assignment.

Though we had originallyplanned to add a staffposition, we were luckyenough to find and talk EdHensley into a contract totake on the main part ofour writing and editingload for the coming year.Ed comes with an impres-

Advanced Methods in SeismicAnalysis, Dead Sea, Israel. Dr.Nitzan Rabinowitz,[email protected]

February4-8—Earthquake EngineeringResearch Institute annual meeting,San Francisco, CA. [email protected]

March8-15—Fourth InternationalConference on Case Histories inGeotechnical Engineering. St.Louis, MO. Abstracts due 12/15/97. [email protected].

16-18—Seismological Society ofAmerica annual meeting. Boulder,CO. [email protected].

MayTBD: Insurance Summit withWSSPC

26-29—American GeophysicalUnion Spring Meeting, Boston,MA. [email protected];http://www.agu.org.

31-June 4—U.S. National Confer-ence on Earthquake Engineering,Seattle, Washington. [email protected]

November11-15 or 18-20—US/Japanconference. Tokyo, Japan; JillAndrews is on steering committee.

He also worked as a writerand editor for the stateDepartment of Education.In addition, he has taughtEnglish, reported for anewspaper, worked as afreelance writer and editor,and been a staff technicalwriter and editor for severalorganizations. Currently, heworks as an independent

If you have comments orquestions about the news-letter or ideas about anySCEC publication, feel freeto email Ed [email protected].



Earthquake Information Resources On Line SCEC on the Web

www.scec.org

HTTP://WWW-SOCAL.WR.USGS.GOV/LISA/NETBULLS/NETBULL_LIST.HTML

Southern California Seismic Network

HTTP://WWW.SEISMO.UNR.EDU

Nevada Seismological Laboratory

Features work by two SCEC-funded researchers, John Andersonand Steve Wesnousky. Contains lists, maps, and seismogram datafrom recent earthquakes. Also: background geologic and seismicitymaps; searchable earthquake catalogs; contact lists, brochures,geophysics degree program information; courses in earthquakefundamentals and scientific visualization.

USGS email [email protected]

National Earthquake Information Center

[email protected]

National Geomagnetic Information Center

[email protected]

National Landslide Information Center

PaleoseismologyHTTP://INQUA.NLH.NO/COMMPL/PALSEISM.HTML

The INQUA Subcommission on Paleoseismicity: content list andauthors for the special issue of journal of geodynamics arisingfrom the INQUA Berlin 1995 symposium on paleoseismicity.

Active TectonicsHTTP://WWW-GEOLOGY.UCDAVIS.EDU/~GEL214/

University of California, Davis—Active Tectonics• Lecture notes (“Contents”)• Problem sets (“Problems”) for this course• WWW links (“Links”) of interest to students and researchers• References

GIS Web SitesHTTP://WAREHOUSE.GEOPLACE.COM/

Bibliography of GIS & environmental applications:

HTTP://PASTURE.ECN.PURDUE.EDU/~ENGELB/Bernie Engel, professor of agricultural engineering: soil and waterconservation, environmental issues, systems engineeering

HTTP://WWW.LIB.BERKELEY.EDU/CGI-BIN/PRINT_HIT_BOLD.PL/UCBGIS/UCB GIS Task Force integrates GIS activities with other resourcesat UCB campus, recommends GIS services for library

HTTP://WWW.NWI.FWS.GOV/THINKTANK.HTML

GIS Think Tank on problems of digital mapping for users of NWIdata

HTTP://FGDC.ER.USGS.GOV/LINKPUB.HTML

List of FTP directories for federal Geographic Data Committee

HTTP://MIS.UCD.IE/STAFF/PKEENAN/GIS_AS_A_DSS.HTML

Paper on how to use a GIS as a DSS generator

See “On Line Resources" on Page 30

Earth Sciences

SCEC Data CenterHTTP://WWW.SCECDC.SCEC.ORG/RECENTEQS

Recent earthquake activity in northern and southern Calif. Maps andearthquake lists are interactive and updated at the time of an event

HTTP://WWW.SCECDC.SCEC.ORG/EARTHQUAKES/CURRENT.TXT (TEXT)HTTP://WWW.SCECDC.SCEC.ORG/EARTHQUAKES/CURRENT.GIF (MAP)

Southern California Seismic Network weekly earthquake reports

HTTP://SCEC.GPS.CALTECH.EDU/FTP/CA.EARTHQUAKES

SCSN weekly earthquake reports archives to January 1993

HTTP://SCECDC.SCEC.ORG/SEISMOCAM/Caltech/USGS Seismocam: waveform displays of data 30-seconds-oldearthquakes in southern California: includes aftershock maps,animations of aftershock sequences and rupture models, and aclickable map of historic southern California earthquakes.

HTTP://WWW.SCECDC.SCEC.ORG/EQSOCAL.HTML

Main page

HTTP://WWW.SCECDC.SCEC.ORG/CLICKMAP.HTML

Southern California clickable earthquake map

HTTP://WWW.SCECDC.SCEC.ORG/EASOCAL.HTML

Los Angeles basin clickable earthquake map

HTTP://WWW.SCECDC.SCEC.ORG/EQSOCAL.HTML

Earthquakes in southern California

HTTP://SCEC.GPS.CALTECH.EDU/CGI-BIN/FINGER?QUAKE

“Finger Quake” ftp (updated frequently)

HTTP://WWW.SCECDC.SCEC.ORG/FAULTMAP.HTML

Southern California fault map

HTTP://WWW.SCECDC.SCEC.ORG/LAFAULT.HTML

Faults of Los Angeles

HTTP://WWW.SCECDC.SCEC.ORG/LARSE.HTML

LARSE home page

Seismo-Surfing the InternetHTTP://WWW.GEOPHYS.WASHINGTON.EDU/SEISMOSURFING.HTML

Clearinghouse of research data & informmation

USGS Web SitesHTTP://WWW.USGS.GOV

General USGS site

HTTP://GLDSS7.CR.USGS.GOV/National Earthquake Information Center

HTTP://GEOLOGY.USGS.GOV/QUAKE.HTML

Earthquake Information

HTTP://QUAKE.WR.USGS.GOV/USGS Menlo Park

HTTP://WWW-SOCAL.WR.USGS.GOV

USGS Pasadena

HTTP://GEOHAZARDS.CR.USGS.GOV/NORTHRIDGE/USGS Response to an Urban Earthquake — Northridge ’94



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HTTP://SPSOSUN.GSFC.NASA.GOV/EOSDIS_SERVICES.HTML

A spectrum of services, some for casual users, some for researchscientists, some inbetween

HTTP://WWW.GGRWEB.COM/Services of information technologies, earth sciences, GIS, GPS, &remote sensing industries

Geodetic InformationHTTP://LOX.UCSD.EDU

This site is the IGPP & Scripps Orbit and Permanent Array Center(SOPAC) and features global (IGS) and regional (SCIGN) continuousGPS archive, SCIGN maps, time series, and site velocities.

GMTHTTP://QUAKE.UCSB.EDU

Helps make shaded relief maps with GMT. Has catalog of mapsproduced by Geoffrey Ely at the ICS/UCSB. Downloadable digitalelevation model for southern California in GMT-readable (netCDF)format. The grid covers the region 121W 115W 32.5N 35.5N at aresolution of 3 arc sec. You can get to the web page from the ICShome page, then click on Mapping, and then Geoff’s Map Catalog.

Preparedness, Disaster ManagementHTTP://WWW.BEST.COM/~TRBU/OES/

California Governor’s Office of Emergency Services: information onEarthquake Preparedness Month campaign

HTTP://KFWB.COM/EQPAGE.HTML

KFWB Quake Page (by Jack Popejoy)

HTTP://KFWB.COM/CUCAMONG.HTML

KFWB Webservice exclusive: trenching the Cucamonga fault:

HTTP://WWW.HIGHWAYS.COM/LASD-EOB/The Los Angeles Sheriff’s Department Emergency Operations Bureau

HTTP://WWW.JOHNMARTIN.COM/EQPREP.HTM

John A. Martin & Associates

HTTP://WWW.EERC.BERKELEY.EDU/Earthquake Engineering Research Center offers extensive, searchabledatabase of abstracts, reports, and other resources. New: “Lessonsfrom Loma Prieta,”with papers, images, and data.

Earthquake Information SitesHTTP://WWW.EQNET.ORG/

EQNET

HTTP://WWW.CIVENG.CARLETON.CA/CGI-BIN/QUAKES

Recent quakes (with a great map viewer)

HTTP://WWW.CRUSTAL.UCSB.EDU/SCEC/WEBQUAKES/Up-to-the-minute southern California earthquake map—latest 500earthquake locations. Java-enabled browsers only.

HTTP://WWW.CONSRV.CA.GOV/DMG/SHEZP/PSHA0.HTML

Probabilistic Seismic Hazard Map, California

HTTP://WWW.ABAG.CA.GOV/BAYAREA/EQMAPS/LIQUEFAC/BAYALIQS.GIF

Bay Area hazard map

HTTP://WWW.WSSPC.ORG

Western States Seismic Safety Policy Council site, an overallearthquake safety information source.

HTTP://WWW.SCECDC.SCEC.ORG/GLOSSARY.HTML#BLINGlossary of terms (in progress)

HTTP://WWW.GEOPHYS.WASHINGTON.EDU/SEISMOSURFING.HTML

Seismic Info Sources

HTTP://WWW.SEISMIC.CA.GOV/SSCCATR.HTM

Seismic Safety Commission—state earthquake hazard mitigationplan

HTTP://WWW.SEISMIC.CA.GOV/SSCLEG.HTM

Seismic Safety Commission legislation page (current state andfederal bills being tracked and analyzed by the Commission)

HTTP://WWW.SEISMIC.CA.GOV/SSCSIGEQ.HTM

Seismic Safety Commission—significant damaging Californiaearthquakes

Internet Discussion [email protected]

Western States Seismic Policy Council discussion group

[email protected] ListServe

[email protected]

Global Volcanism Network

[email protected]

Research in quaternary science

[email protected]

Seismological discussion list (SEISMD-L)

[email protected]

Earthquake discussion list

Conferences, EventsHTTP://WWW.SCEC.ORG/CALENDAR/ANNUAL97/ANNUALMEETING.HTML

SCEC annual meeting information and registration

HTTP://WWW.SEISMO.NRCAN.GC.CA/ESSSA97October 5-8—Annual meeting, Eastern Section, SeismologicalSociety of America, Ottawa.

HTTP://WWW.GEOSOCIETY.ORG/MEETINGS/97/INDEX.HTM

October 20-23—Geological Society of America annual meeting,Salt Lake City.

HTTP://EPDWWW.ENGR.WISC.EDU/DMC/October 22-24—Using GIS for Disaster Management, Madison.

HTTP://ACL.LANL.GOV/GEM

October 23-25—General Earthquake Modeling Workshop, SantaFe, NM.

HTTP://FERMAT.GEOL.UCONN.EDU/INFO/TAIWAN

November 3-5—International Conference and Sino-AmericanSymposium on the Tectonics of East Asia, Chungli, Taiwan.

HTTP://WWW.ERIM.ORG/CONF/CONF.HTML

November 17-19—12th International Conference & Workshops onApplied Geologic Remote Sensing, Denver.

WWW.AGU.ORG/MEETINGS/FM97TOP.HTML

December 8-12—Fall Meeting of the American GeophysicalUnion, San Francisco.

HTTP://WWW.EERI.ORG

February 4-8, 1998—Earthquake Engineering Research Instituteannual meeting, San Francisco.

On Line Resources continued



SCEC Board of DirectorsSouthern CaliforniaEarthquake Center

Administration

Center Director - Thomas Henyey

Science Director - David Jackson

Administration - John McRaney

Education - Curt Abdouch

Knowledge Transfer - Jill Andrews

Outreach Specialist - Mark Benthien

Bernard Minster, Vice ChairmanScripps Institute of OceanographyUniversity of California, San Diego

James DolanUniversity of Southern California

Leonardo SeeberColumbia University

David Jackson, ChairmanUniversity of California, Los Angeles

Ralph ArchuletaUniversity of California, Santa Barbara

Robert ClaytonCalifornia Institute of Technology

James MoriUnited States Geological Survey

Mail your name, mailing address, phonenumber, email, and check for $25 to:

Southern California Earthquake CenterUniversity of Southern California

Los Angeles, CA 90089-0742

Have questions? Call, fax, or email:

Tel: 213/740-1560Fax: 213/740-0011

Email: [email protected]

SCEC Quarterly Newsletter

One year’s subscription costs $25.00. Pleasemake payment by check, money order, orpurchase order payable to “University ofSouthern California/SCEC.” Please do notsend currency. Price includes postage withinthe U.S. Overseas airmail costs or specialcourier services will be billed. SCEC scientists,students, and affiliated agencies receive thisnewsletter free of charge.

To Subscribe

SCEC on the Internet

SCEC Knowledge Transfer and Education Programs are reachablevia electronic mail. Ask general questions, make requests, send usinformation for use in our resource center or for consideration forpublishing in the next newsletter.

[email protected]

WHEN: October 5–7, 1997

WHERE: Doubletree Hotel, Costa Mesa, CA

Sunday, October 5

10:00am Field Trip—San Joaquin Hills6:00pm Icebreaker and Dinner7:15 Poster Session8:00 Advisory Council meeting8:30 Meeting of SCIGN Coordinating Board

Monday, October 6

Session I: Plenary Session

8:00am Welcome and Introduction (20)SCEC Science Program (30)The SCIGN Project Bock (20)Report of Knowledge Transfer and Education (30)

9:40 Break10:00 Short Research Reports from Group Leaders11:15 Phase III Presentation12:45 Lunch

Session II: Working Group Meetings

1:45 Group A: Jackson3:15 Group B: Day4:45 Groups C & G: Sieh, Knopoff6:15 Dinner— Speaker: Arch Johnston: “New Madrid”7:45 Groups D and F: Clayton, Hauksson9:15 Group E: Hudnut

Tuesday, October 7

8:00 SCEC II: The Future Proposal—HenyeyNoon End of SCEC meetingNoon Lunch for Advisory Council &Steering Committee1:00pm ROSRINE meeting—Schneider

FOR DETAILS & REGISTRATION:http://www.scec.org/calendar/annual97/annualmeeting.html

SCEC ANNUAL MEETING

Southern California Earthquake CenterUniversity of Southern CaliforniaLos Angeles, CA 90089-0742

ADDRESS CORRECTION REQUESTED

SCEC Quarterly Newsletter is published quarterly by theSouthern California Earthquake Center, University ofSouthern California, Los Angeles, CA 90089-0742, USA,telephone 213/740-1560 or 213/740-5843, fax 213/740-0011,email: [email protected]. Please send requests forsubscriptions and address changes to Mark Benthien.

SUBSCRIPTION INFORMATION

SEE PAGE 31

Inside this issue:

Feature Articles

Knowledge Transfer Retrospective ........................................... 3

Portrait: Thomas Dibblee ............................................................ 8

SCEC Departments

What Is SCEC? ............................................................................. 2

From the Center Directors .......................................................... 2

Quarter Fault: Raymond ............................................................ 6

SCEC Scientist: Ralph Archuleta ............................................ 10

Positions Available .................................................................... 15

Recent Publications/Abstracts ................................................ 16

Off-Scale ...................................................................................... 22

Global: Abiz Earthquake Reports ............................................ 24

Activities Reports

Caribbean Paleoseismology ..................................................... 26

Calendar & SCEC Notes ........................................................... 28

Earthquake Info Resources On Line ....................................... 29

SCEC Annual Meeting Agenda ............................................... 31

Nonprofit Organization

U.S. Postage Paid

University of Southern California

Contributing writers:

Jill Andrews, SCEC

Mark Benthien, SCEC

Hugh Cowan

James Dolan, USC/SCEC

Thomas Henyey, USC/SCEC

David Jackson, UCLA/SCEC

Kristin Weaver, USC

Photographs:

Jill Andrews

Helmut Ehrenspeck

Michael Forrest

Photo enhancement:

Mark Benthien

Producer: Jill Andrews

Editor: Ed Hensley

Feature writer: Michael Forrest

SS CC EE CC

SS CC EE CC

SCEC Quarterly Newsletter

volume 3, number 2scecinfo.usc.edu/news/newsletter/issue32.pdflished, center scientists launched a...

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