·'-' ... ,

:: -~'"'•'- ..... 1- (.~tt-ORNIA Ttif RESOURCES AGENCY

DEP ... RTMENT Of COH$ERYATIOH

••

DIVISION OF MINES AND GEOLOGY DIVISION HEADQUARTERS Rf50U~CES IUILDIHO. ROOM 13'1 1116 NINTH STRfloT SACAAMENTO, CA P58l •

Diattid OM~,; LOS ANGELES Junlpera Serra lld:g,, atn. 1065 107 Soutt. Brovdway 90012

James O. Berkland

MCR>.MENTO RWIOIJIWllf. lldg., R111. 118 l.Cl6 Ninth St,..t 95814

Sr. Engineering Geologist Land Development Engineering & Surveying County Government Center, East Wing 70 West Hedding Street, Seventh Floor San Jose, California 95110

Oear Jim:

S4N FRANCISCO Fitrry hUdlng 9•111

(415) 557-0413

August 31. 1976

EDMUND G. IROWH JI., Go.., ...

This Is to ackna,.iledge receipt of the 36 geologic reports and report addenda with your letter of August 9, 1976.

Host of these reports lie within Special Studies Zones and have been reviewed and approved by you on behalf of Santa Clara County. These reports will therefore be open-filed in compliance with the Alqulst-Priolo Special Studies Zones Act.

' The reports for sites outside of the Special Studies Zones

will be filed informally.

I note that figure 2 and the Appendix are missing from report no. 8 (Gillette property, Call of the Wild Road, file no. 12C7S.1). Please submit these to complete our files.

It is also noted that most of these reports rely heavily, If not solely, on geophysical data and a review of the literature., This is especially true of the R.B. Rose reports, which comprised 18 of the submitted reports. As you are aware from previous discussions, I

.. • ..

-2-

am concerned with the adequacy of fault Investigations being conducted throughout the State (see enclosed CDHG Note 49 and abstract}. With­out strict local reviews, It Is unlikely that the quality of these Investigations will significantly Improve.

EWH/mkr

cc: A-P file

Enclosure

'

Sincerely yours,

EARL W. HART Office of the State Geologist RG 462 CEG 935

•

I ,, .

County of Santa Clara California

August 9, 1976

State Geologist c/o Earl Hart Geologist, CDMG Ferry Building San Francisco, CA 94111

County Government Center, East Wing 70 West Hedding Street, Seventh Floor

299-2871 San Jose, California 95110

REGARDING: GEOLOGIC REPORTS SUBMITTED TO SANTA CLARA COUNTY

This letter accompanies 36 copies of geologic reports (list attached) which this office has received pursuant to state and county regulations, At the local level, ~1J ___ :i;:e_p9rts have been approved by me although several required additional cl.ar-ification or documentation prior to approval.

In addition to the reports governed by the revised Alquist­Priolo Act, we are sending additional reports covering single sites in Special Studies Zones for your open files,

I acknowledge and apologize for the delay in delivering these reports to you, and I expect to remain "current" in the future.

<;;:;,..., (3,~-"'t. "

•

JAMES 0 • BERKLAi~D Sr, Engineering Geologist

JOB:md

Attachment

An EQual Qpportun1ry Employer

l.

2.

3.

4.

5.

6.

7.

B.

9.

10.

11.

12.

11.

15.

16.

17.

lH.

19.

2.0.

21.

v. /1.

2h.

27.

R~PORlS TRANS!>' ITTED TO STATE GEOL()(; IST 8-lo-7f...

STREET

Si~rra Ko.ad

llarn<Jrd Road

Corra 1 itos Lane

Crothers lload

Call ol the Wild Ro3d

Ca 11 <>l tlit• Wild Road

El Cami no lliguera

Ev.:in:=: Road

Hubbard Way

Kennedy Ro.:.id

Kent Wny

Mt. Hamilton Rd. (Off)

Mt. Harni Hon Rd. (Of 0•

Mimos:i Court

Norwood Avt.•n1H .. '

Quin1hy K1) 0Jd

Wuud Hond

J'urter

H.t~<lwuud Gu l.c h Ko.:1tl

S11rnrni t Ho<t<I (nrf)

APPLICANT

Snodi;?;ras C'

Ila yes

Bay

Cadwallader

Yim

Hawkins

Mueller

Gillette

Evans

Serpa

Wiln1ot

Fol lmar

Illa ke

Chet al:'d

Ross

Borges

R11floln

lfl•nm(' n

Stroud

Souzn

SCCo P"hlic Works Alon?o

FlLE ~O.

7'lR75. 5]4

18S75. I

12P75.1

21S73.3l

76Rl7.600

17575.10

76B12.3531

12C75.l

74B15, 865

74M15. 8 76

76Gl 7. 226

76811.3527

73Ml2. 724

74M12 .853

17575.15

17S76.4

4S 75. 7

75Rl8.557

751ll2. 3514

18576.I

"14Rl 7. 508

72B4. 3(19)

1SS7'i.2

7'iM12 .YV,

75Hl7.57t-.

l!S74.ll

llATE 1IPPROl'Ell

io-24-76

\-<-7f

5-10-76

4·-9- 75

4-23-76

8-28-75

b-7-76

4-<J- 76

2-11-76

6-5-75

6-7-76

2-26-76

12-30-75

12-26- 75

9-17-75

i- 7 - 76

1(1-7-?'i

111-H-75

!..-14-76

H-2H- 7">

:.~~<l-7b

\j-/,J-7C)

2- l!>-7b

Reports T.-ansmit ted to ;>tate Geologist Page 2

STREET

29. Hi 11 side Road

30, New Avenue

31. Clayton Road

32. Rock hi 11 Road

33. Klein Road

'fl -lo -7(,,

APPLICANT

Weed

Ma lone/Maas

Harris

Dean

Elmer

FILE NO.

75Ml2. 938

22S76.13/ 22875.14

18S75, 14

75Ml5.969

17572.8

DATE APPROVED

11-18-75

8-5-76

6-25-76

8-9-76

The following addenda should be inserted into reports previously transmitted:

34.

35.

36.

Silver Creek Road . ..... (Addendum) + ,.r;~:····' I "t "'•

Fleming Avenue (Addendum Trench log)

Lazy Lane (Addendum)

,

18574.5 (·l'l~Tfl'"'

Raferty/ Rasmussen

Edens

17P74.4

18S75.5 7-29-76

---· -· ··---...,·· •' ----···~- .. ~-----·· -s fAfE G<'dOC,1<TJ 1

,. <'f' y

R. Burloo Ras•, M.A. G&:QLOGl51"

E'.:NGtNEElll:INC. GIEOL.O~ tc;:-'1.,.ll'"C~HIAI fltt;(tlll.~AT'IONI)

I~------·~.

Af l

ALLIED GfOPHYSICS

P.O. l!!llo:iic !583 ii,ti,N .J.Os£. C:::.A.. 11181QG <A-Oel 2&B-2soa Ae"'"''' /-'J.,-71. - 9~rt]

ENGINEERING GEOLOGY SECTION LAND DEVELOPMENT ENGINEERING COUNTY OF SANTA CLARA 1555 BERGER DRIVE SAN JOSE, CALIFORNIA 95112

Stroud Minor Land Division

AP 517-05-05) 19+ acres

East side Sanborn Road

Santa Clara County CA

SWi Sec. 14, T.8 S., R.1 W.

Castle Rock Ridge Quadrangle

In-depth Geologic/Seismic Report

R. Burfon Ro••· M.A GP:OL.OGJST

ENOJNl!:ERINQ. CEOl.OGl•T (C°"Ull'QFOl"'llA RlfQll•TllllA"i"ION)

ALLIED GE0Pl1Y51CS

P.O. BO)( 583

B.-.N .Jo&~. eA. !il!l1oa

Mr. Tom Stroud 1655 Johnson Avenue San Jose CA 95129

Dear Mr. Stroud:

January 27, 1976

Re: Minor land division APN 517-05-053 19+ acres East side Sanborn Road Santa Clara County CA

Thank you for the pleasure of our studying this land parcel for your proposed development and use.

This letter is a summary 9f the findings, conclusions, and. recommendations; as sU:ch part of the report.

Your sites:. are dee.med suitable for the construct ion of. two homes with a mutual access roadway from Sanborn Road, usi:ng a private bridge across Sanborn Creek

All structures should be engineered in design. A g factor of 0.25 acceleration should be used in design, applying to living quarters, from a geologic and seismic viewpoint.

No fault trace was found within the planned homes area, based on our geologic, seismic, and reference searching; correlated to the two seismic refraction survey lines.

Mr. Rogers E. Johnson, graduate geologis~ worked with me in the field and report phases.

Please call me if there are any further questions, at your convenience.

Respectfully yours;

C.E.G. 760 G.P. 397

7 copies

( DWOOO Cl 1 -41 Ml. ·ro. C-Al

STATE OF CALIFORNIA

.Delineated In · compllanc• with Chapter 7.5, Dlvlalon 2 of tho Callfornlc Publlc Ro1ourco1 Code

CASTLE ROCK RIDGE QUADRANGLE

0 APN 517~05.;053 OFFICIAL ril1AP

R. Burfoo Ro,., MA G!i:OL.CIOl~T

ENGINll!:ERINO Gli:01..0(11eT 4t:;ALll'"ORNIA RICGl~TRATtotol,

ALLIED GEOPHYSICS

P.O. E;l.Q)( 993 1'-.A.N .JQSE'.: 0 CA. 9.51011

APN 517-05-053

In-depth Geologic and Seismicity Report

Stroud Minor Land Division

East side Sanborn Road Santa Clara County CA

~; January 22, 1976

19+ acres

Introduction; This geologic and seismicity report is

addressed to the pertinent' and basic geologic factors

of the site acreage and to the Alquist-Priolo Special

Studies Act of the State of California (1974). Two

proposed homesites in a two parcel land division, forms

the background of the study and.conclusions. The report

is favorable for wood frame construction with engineered

foundations; together with specific attention to the

slopes involved and their erosion prevention planting.

Three field days were spent on the project, including

two seismic refraction survey lines.

Location; The total acreage lies easterly from the area

drainage creek along the east side of Sanborn Road above

Saratoga, 1ying one mile east of Highway 9; being in the

517-05-053 2.

SW~ of Section 14, Township 8 South, Range 1 West, In

the northerly portion of the U.S.G.S. Castle Rock Ridge

quadrangle (scale 1:24000).

Data: Essential geology,.structure, fault, seismic, slope

and topography are shown and correlated on the plates

between this written summary and the bibliography. An

area index map precedes this portion showing the Alquist­

Priolo Special Studies Act zoning; accompanied by a road

index. Field mapping was augmented by two seismic data

refraction line surveys and pertinent reference search.

An appendix of more general seismic and geologic coverage

is included for additional perspective and guidance.

Regional and Site Geology: The property lies lies on high

relief terrain in the San Andreas rift zone (Alquist-Priolo)

facing to the south west in slope at the house sites. It

lies between Castle Rock Ridge to the west and the ridge

connecting Table Mountain and El Sereno Mountain to the

east. These ridges and the N 4o0 W trending rift zone are

the major structural features in the area. Bedrock west

of the fault zone consists primarily of Mid-Tertiary age

elastic sediments; to the east of the fault zone typical

Franciscan, Cretaceous to Jurassic, assemblage rocks are

found: these latter underlie the parcel studied.

Several geologist have mapped the Sanborn Road area

517-05-053 J.

on a broader basis for governmental agencies. The three

most pertinent publications are Rogers (1972), Sarna -

Wojcicki, et al (1975) and the Alquist-Priolo map (1974).

Neither Rogers nor Sarna - Wojcicki indicate adverse site

geologic conditions on the Stroud property. The Alquist­

Priolo map shows the property lying within the San Andreas

fault zonir.g and a fault following the bed of Sanborn Creek

which is the western boundary of the parcel. This fault

is probabl~ the contact between Franciscan sandstone to

the east and Franciscan mafic intrusive rocks to the west.

Rogers geologic map shows this. contact farther east near

the center of the Stroud property and maps it as a probable

stratigraphic contact. ·.

Our specific site study map shows that the Stroud area

occupies a portion of a westerly facing steep slope and a

narrow irregular flood plain of Sanborn Creek. Geologic

materials on the site consist of an unknown thickness of

alluvial deposits adjacent to Sanborn Creek and a thin

covering of colluvium and soil overlying the Franciscan

assemblage. These Franciscan rocks consist chiefly of a

hard, fine to medium grained meta-sandstone and a small

sliver of mafic intrusive rock near the south west boundary.

Nature of the contact between the two rock types was not

determined because of poor exposure and distance from the

house sites, but it is probably a fault contact judged on

the regional geologic environment. In any case, our study

and geologic plate shows that almost the entire property,

517-05-053 4.

including both proposed homesites, is underlain by the

meta-sandstone. Heavily slickensided sandstone float was

observed on a small knoll on the upper (easterly) portion

of the property. Air-photos from Santa Clara Co. Dept.

of Transportation (scale 1:12000, Nov. 1971) show a NNE

trending lineation intersecting this area and continuing

over the ridge to the east. No evidence of deep seated

ground failure was detected on or near the parcel although

some soil creep was evident.

Evaluation of Geologic and Seismic Hazards -

Surface Ground Rupture: Structural study integrated with

the two seismic refraction~ survey lines indicate that a

continuous sandstone bedrock foundation underlies both

house sites. Therefore, the danger of ground rupture is

minimal. However, there is everywhere in a major active

fault rift the low probability and possibility of new

rupture traces being formed in a major earthquake.

Ground Failure and Landsliding Hazards: The stability of

the hard meta-sandstone bedrock appears to be excellent.

However, a combination of steep slope, excavation for the

acceGs road, and the addition of foundation weight will

probably reduce this high stability some. Future seismic

shaking will reduce the magnitude of stability of the steep

slope at the house sites and should receive engineering

design attention.

517-05-053 5.

Seismic Shaking: Seismic shaking (magnitude, intensity,

and duration) is a significant hazard in any area close

to the San Andreas fault zone and structures should be

designed and built accordingly. The referred to rig~d

meta-sandstone underlying the proposed homesites should

provide excellent foundation support where little, if any,

amplification of seismic waves nor extended duration

should occur. A magnitude of plus 7.5 earthquake may be

experienced along this sector of the San Andreas fault.

Recommended structure design should include an acceleration

factor of 0.25, from a geologic and seismic viewpoint.

Flood Hazard: It should be noted that the Lake Ranch •.

reservoir dam which is located approximately one mile up

stream from the Stroud property (see quadrangle map) now

straddles the 1906 trace of the San Andreas fault. This

dam was damaged but did not fail in 1906. Consequently

the possibility exists that the next major to great earth­

quake on the same trace could cause failure and flooding

downstream. The two proposed homesites studied are at an

elevation of 100 to 120 feet above the stream bed. We

recommend calculations be made of the potential height of

flood waters in the ev-ent of complete dam failure when the

reservoir is at capacity as a factor in house elevation.

Erosion: The owner of this property has removed an area of

vegetation in the vicinity of' the planned homesites which

517-05-053 6.

is necessary. However, additional removal for access and

actual construction should be limited as much as possible.

Construction of an access road to the eastern and higher

portion of the property could cause definite erosion·

problems and is not addressed in this evaluation. Present

bare areas should be replanted as thoroughly as possible

in order to reduce potential problems from accelerated

erosion during future heavy rainfall runoff.

Seismic Refraction Survey Data: Two reversed recorded 180

foot length seismic refraction lines were surveyed, with

their positions shown on an index map. The results are

included in the Time-Dist~nce graph and the Seismic profile,

as computed.into a cross section. Location of the lines

crossed the proposed home sites and were across the strike

direction of regi.onal fault traces. A Bison summing or

slgnal enhancement seismograph was used in the field. The

technique measures sub surface shock wave travel times in

milliseconds, calculating the ground velocities in feet

per second. Depths to higher velocity horizons are shown

from the surface, entered on the Time-Distance graph and

used in profile construction. Three velocity horizons

were found.:

v~ .)

1100-1500 ft, per sec.

4000-5000 II " "

6000-10000 " II II

Organic soil & colluvium

Bedrock (Ks) tight cracks

Fresh bedrock

517-05-053 7.

Seismic refraction interpretation, geology, and vicinity

reference d.ata are evaluated in context.

Conclusions: It is our opinion, as based on the geologic

site mapping, references correlation and structure study,

that this site is favorable and suited to the proposed

two home construction within the limits of the index fuap

positions cf the seismic refraction survey lines, with an

access roadway from Sanborn Road. This conclusion includes

the geologic and seismic recommendation made in this study

report as requisites. Field days exceeded three.

Recommendations: .-

1.) Included as cited throughout report

2.) Replanting of cleared areas after construction

J,) Engineered foundations and structures to meet 0.25

g acceleration as a design minimum

4.) Rainfall erosion control in construction areas

5.) Flood hazard control of housing elevation.

Rogers E. Johnson Graduate geologist

7 copies

Respectfully submitted,

R. Burton Rose C.E.G. 760 G.P. J97

=

'

Stroud klnor Land Division

APN 517-05-053 19+ acres

East side of Sanborn Road and creek

Santa Clara County CA

'

Approximate scale 1 In. = 500 ft.

Property Outll~e Map

lfrom Santa Clara Co. cadastral survey: Sheet 125 - Jan. 1970)

i -j I

. __ j

Stroud Minor Land Division

APN 517-05-053 19+ acres

East side of Sanborn Road and creek

Santa Clara County CA

SI te l n '!lest Sec. 14, T .8 S., R.2 W. Sea I e 1 11= 500 1

Contour interval = 40 ft.

Site Area Topography

(from USGS Castle Rock quadrangle: enlarged)

...

~ ' '

i

N' I

---

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. '-----. . =

,., __ _

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'J"o\03ic c.on-1-,.c+ Scale..: 1,;~ 500' C.I •'Id

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TABLE OF RE:LllTIVE GEOLOGIC STABILITY CONDITIONS

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{.'.'-':') ?I 1'7'"'"' frTl'> r-, !I ~ E! ~,;:~ Jlx,)j ~ \.:.1 INSTRUMENTS 5703 - 36th Strt~t West

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OPEH/.\TOR

TRAVERSE . C T.t:'..O h l?AA""S'.,.~ ~ "°""''# A/3::1"•.tF

LOCAYlON /DESCRIPTION -'--------------------------

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,Stroud

A-/1..,-a t:' -/141-.0

APN 517-05-053

Seismic Refraction Survey Line

References

Map .showing recently active breaks along the San Andreas fault between the central Santa Cruz Mts. and the northern Gabi Ian Range CA: Sarna-Wojcicki, Pampeyan, E. H., and Hall, N. T •• U,S.G.S. M.F. 650 (1975)

Solis of Santa Clara County: Soll Conservation Service

US Department of Agriculture ( 1968)

,,. Interim Report and Study l/aps: Santa Cruz Mts. (1971)

California Division of Mines and Geology Santa Clara County & So. County Area, Prel. Rpt. 18 (1973)

Geologic Guidebook of the San Francisco Bay Counties: California Division of //,Ines, Bui letln 154 (1951)

Proceedings of Conference on Geologic Problems of the San Andreas Fault System: Stanford University sessions, Publications/Geological ~.ciences (1968) (1973) -

Geology of Northern Callfornla, Division of Mines and Geology

Bu I I et In 190: Ca 11 f. ( 1966)

Intensity Distribution of San Francisco Earthquake 1906; adapted from Carnegie Institute Report, Map 23: as reproduced in "Earthquake Enginee.ring", p. 175 (1970)

Maps:

U.S.G.S, topographic map 1:24,000 Scale 1 In.= 2000 ft.*

Geologic Mep of C'llfornla: San Jose and San Francfsco sheets 1 :250,000

*Castle Rock Ridge U.S.G.S. quadrangle 1:24000 (1968)

Geologic ma~ of the Sargent-Berrocal fault zone .,.CA: Sorg, Den!lfts H., and McLaughlin, .Robt. J., 1:24,000, u.s.G.S. m.a.p MF-643 ( 1975)

Setsmlcity

Plates -- Data

•

C'I

0

EXPLANATION

~ ....... ~~ .. ~ GL TC"

UAJOR ~AULT ZONES Tt~SITE 011" MODEF!N ·'TE:C:'TONIC C.R!:EP­

AFF!e'flNG MAl\l•f>A.AtJ~ STRUCTURES

GL.sGEO'OINETER L.INE C:~O!i!>1Nt;i. ~,&l)LT ZONE

E.G.ATHQUAKE EPICENTERS

P~t. 1'930 19~0 TQ l'!llftT fdot• liiffd IPIO~nllud# of mli•t 1,,.,,.-tMt •orthq~o••• ~ha~~I

•

Mineral Information Service CA

• V<WCHnut

Gl- Cri!-!'k "V

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• VoJ'l PLEASANTON

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C1'LIFORNL\ DmsIO:< OF MtNES -'"" GEOLOGY Bull 198

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: m i ' ' Preliminary Map of

MAXIMUM EXPECTABLE EAFm!QUAKE INTENSITY D. , All1,1r0$ 8 !

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Pr~llminciry mop (If ma.v.irr11,:m ~lCPll'-t;;ibl'I i;¢rr~·n~ut:1k~ int•11.t.itf in C:cli"fornia..

APPENDIX B

General Comparison of Scale5 Used to Rate Earthquakes at the Earthquake Epicenter*

In.tensity

Magr1it• Modified )41!.r(:&l.li lWSsi ~ron1' Richter Seal~ $C~ll!! ~uivalent

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Total de~truction wet!tk :1t't'Ui=:turee, ~(lttSiderallle d.ma.g!J Wll!!ll-lliuilt. liiltru.ct.\U'ell

MMOfU.j" and. froie st:ructur~s 0011111only destroyed. Only best. bu.ild.ings surrlv.

DeliC~~ly SUB~~ cbjecu ~ift9

c ... t:$ rocked, vi~ 1;at.t.led

Dishes , vi.;'idcw11 bnik.i pe11d11ium clock$ If~

ruxr.iitura l!KiV.4, d>jact.w upset:

Mcm"UtDel".l.t8 ~ walls d.a.m. f11~i t\lre Oftl'­

tlll'l'led. sand~

rn11d eject.d. Ch~• in well-Wiit.tet" leveh

Po\'lnd.at.iorui d~4. u,r':der~gro'QI'l"- pi.pa brok•n.

Cro1J.~ b~dly cracked, rails bent. Wat.er • J.opr-ed. uve:c- b~

Bt'Ood .fis&uns r f'anl'­•eazpa. Un~ic-g:rcm.4

pips.a (JUt of ••nioti

Ac~lmrat.ion ·~~ gr&vity. Wa~• seen in r;rx-ol,ltJ.ii. I.in9t. of: sight. and. i..v.1 distort~, cbjecu th.niwa. in ah

Nor.Et ~it~ an.d. :ln.ten.111.t:y ot an earthquakll!! are enti~ly diff•Rnt 111111e.u.urmnsnU of ·~· ~ m- •!feet:.,. &t"J.d it=an only ti• eon::pareQ •t. the e,.uthi;ru~• 1tpit::enut-~

""'~it:ud!!! - i11 • n.U!B::ier d4il:"t~d. tram in,1;t~ntal il'lllM1,1~.mente, and. is the. mau~ l)f th.ii! enarqt 1=*leu.d. by t.he eartb~e.. There i~ ~e Ma.snitl,113..e cal.cul.ated for each eatthqllak.11!!1.

Int.P.naltv - i• a local i:.o:t.in.9 of e.i.....'""thqu.!ko!; effecb Qb:sll!rved and. ~ported by pW.Op).lft at any ¢ven loe.t.iOll .. lnten.~:i.t~ r111.tir'l.i;i:s f¢~ one e~~l.Lake va.ey c~i~rably d~p.:cnding on di:s~~O!; f:com • .,tcentl!i=, th• ti4.tlll9 of th~ 6oil and. ~ beneatl", thll!! d:Jeervert oWl4 thei Qb:111•~:i-'s ~nt.sq:iRt.o.t.i".l'n of •~D~ Sll!en or felt...

36

IN9;"rRUMENT9.

A NE\J\/, IMPORTANT ADVANCEMENT IN SUBSURFACE EARTH INVESTIGATION

fE HDRIZONTAl. range and deptll capability wilhoul e~lostvet It doubled.

The depth capability of engineering seismographs has been dramatically increased by the usa of SISON Signal Enhancement concept by which seis­mic waves from impact sources are stored and summed. The summation from repeated impacts

FIRST IMPACT

Here is the Signal Enhancement technique In ac­tion. It adds together signals from repeated im­pacts. The true signals always arrive at the same time and add directly, whereas earth movement noise generated by vehicles, mining or drilling ma~ chine'3, high ten$ion 11.tires ot wind, arrive at random tirnes <:tnd tend to cancel out. The complete wave­form is displayed permanently until erased. The Vertical Marker is positioned at the dcsirGd point on the waveform to g~ve the digital t:me resJ"Jing in milliseconds.

lJSED IN 1-!lqhwRy Ro11t~ St>h.~.ctioi;." P1r··1:i!'./'1<?. Rou!(l

,''·'

brings small signals up out. of the background noiae. Tt1e onhancement feature combined with continuous display of the waveform and digital read­out of travel times opens new fields of applications.

)' ;.~· . .'.,·:·.,,; .. ~:..;.,, ..... ·. -.... ··

~,·····:~A·~:~'~·--· .. , . ..:..~>, ,,.1·>;.~ ,·,...,. "':'("'"""'"

Selection. Bidding and Estimoting. Water Well Lo­cation. Foundatiorl Studies. Darnsite Investigation$. Minin9 Investigations. Geological Studies. Gravel and Rock Prospecting. Water Supply. Sanitary Landfill Evaluotion. Slope Design. Landslide In­vestigation.

ALLIED GEOPHYSICS p_o_ EJox !$83 ,cl;,111,1'>.1 .,10'.';E, CA. 9!U06

PRil'!ERA CONVE::CION INl'.i::RAMERICANA DE RECURSOS MI~l!RALES - 1951 Institute of Mineral Kesources of Mexico

Jurrorican Institute of Mining and Metallurgical t:ngineers Panam.erican Institute of Mining Engineers and Geologists

MINIATlffiE SEISMIC REFRACTION MAPFING IN MINING AND CIVIL EIDII1El1llli'G

R. BURTON ROSE X

Abstract

A restlr.lo of a very lightweight, portable multi-channel seismic refraction instrument design XX and its import in the field:> o:r mining and civil engineering studies. This compactness and portability permits ap.!Jlication in many shallow geologic, f'oundation, ground water ar:.d placer problems previously either too inaccessible o~ too lir::ited in scope for large scale seismic study.

P1•aotical f&.c: to1·u in. such remote aEu/ or shurt period applications depend on (a) lightnoss of' oo.o.plete s ei>Jroograph uriit, totalling about 100 !JCLcn::l.s; ( b) :i.ro.rn.ediate fiold exanination of tha photographic recO':'ds; ( o) specialized geophy:3 icul personnel can be lim.i.ted to one '.'.lperator-intorprotor; ( d) q uic;; f'iold layout changes and survey progress; ( e) i·oduotion of total nun1ber of' test dril.l. holes, or elim.ination on reccn:naissance basis; ( f') cost compar:ison

. ·t;o test drillinr, approx:i.nntins 10 percent; <rnd (g) ;~j_nimal basic invostrnont or s urv0y overhead coi;ts. Depth peI:te crati_o;~ approximates

,,..., . one-third the lengtil from shot point to far recorder, extend.able to v·- any maximum depth required. Illustration exo.moles represent typical instances of field

problems and re-'lults. •

LEV.l\NTAMIEIITOS DE HE.l!'R.'\CCION SEISMICA EN UINIJiTV''Rfl EN LA INGEIJr.t:Rii1 MIHE;H.A Y CIVIL

R. BURTON ROSE X

Abstracto

Un resllr,ien sobro un instrwnento rot.:y livia.no, portatil, de multi-canales p;~ra ref:i.0 aooi6n seis!tica y su inportancia en los campos de estudio de :i.ngenieria roinera y civil.

J,o compacto y port1til deJ_ aparato permite Stl aplica(lion · en n;iuchos s i tics con problorua geologioo por el esca::rn fondo d<3l ci.ciiento, por cgua on el tcrreno o pol.' obstticltlos en los placE•:t·es qu"' anteriorrar~nte fueron, o t.il!Y ina::::cenible:J o muy 11mita&os on extensi6n para un 0stlldio se.ismico e!l gran e:3oala.

Ln penotrac:l.6!1 pro.funda aproxima un tercio l.a <listancia del punt~o de cxplo:Ji6n a1 rcg:i.stro a d.istancia, qua es ext•3nsible a cualc1uier profu.Dlidad. quo se .req_ui0t·a •

..J :..;: Geoloeist-r,eophys 5_cist, Box 583, Sun Jo!;o, Calii'orni_a, U .s .A. ~

?a.tents are pe;::ding - Cent;11ry (;c;,:i:ihysical coi·poration.