, )

PB 301164

) Prepared for theNational Science Foundation

under Grant GI 44056

UCLA-ENG-7653JUNE 1976

R.T. EGUCHIK.W. CAMPBELL

C.M. DUKEA.W.CHOW

J. PATERNINAREPRODUCED BY

NATIONAL TECHNICALINFORMATION SERVICE

u. S; DEPARTMENT OF COMMERCE_ SPRINGFIELD, VA. 22161 _

PRINCIPAL INVESTIGATOR: C. M. DUKE

SHEAR VELOCITIES AND NEAR-SURFACE GEOLOGIES ATACCELEROGRAPH SITES THAT RECORDED THESAN FERNANDO EARTHQUAKE

,}

ASRA INFORMATION RESOURCESNATIONAL SCIENCE FOUNDATION

UCLA • SCHOOL OF ENGINEERING AND APPLIED SCIENCE

50272 -101

REPORT DOCUMENTATIONPAGE

1. REPORT NO.

NSFjRA-761696,

4. Title and Subtitle

Shear Velocities and Near-Surface Geologies at AccelerographSites That Recorded the San Fernando Earthquake

7. Author(s)

__~~~.__Eguchi~ __K W. Carnpb~ll, c. r~. Duke, et al9. Performing Organization Name and Address

University of CaliforniaSchool of Engineering and Applied ScienceEarthquake LaboratoryLos Angeles, California 90024

5. Report Date

June, 19766.

8. Performing Organization Rept. No.

UCLA-ENG-765310. Project/Task/Work Unit No.

11. Contract(C) or Grant(G) No.

(C)

(G) GI44056f----------------- -. --.

12. Sponsoring Organization Name and Address

Engineering and Applied ScienceNational Science Foundation1800 G Street, N.W.Washington, D.C. 20550

15. Supplementary Notes

16. Abstract (Limit: 200 words)

(EAS)13. Type of Report & Period Covered

14.

This study seeks accurate near-surface shear-wave velocity data at several sitesin the Los Angeles area. These data currently are being used to correlate bothseismic velocity and strong-motion indices with local near-surface site conditions.Included is a compilation of refraction seismic survey and geotechnical data on thirty­three sites selected within the Los Angeles, California area. The sites were chosenon the basis of two criteria: (1) their relative closeness to strong motion accel­erographs that recorded the 1971 San Fernando earthquake; and (2) their geologicrepresentativeness. The main areas of concentration for these surveys were WilshireBoulevard, Downtown Los Angeles, and Pasadena. Using the refraction technique,shear wave velocities and layer thicknesses down to approximately 70 feet weredetermined. Geotechnical data on geology, age, lithology, and depth, from severalsources, were compiled for each site. Also provided is a summary of new fieldtechniques developed and applied during the study. Results for this work phaseare included in Appendix A.

1------------ ----------------~------- --------------- - - ..----~---------------j17. Document Analysis 3. Descriptors

EarthquakesSecondary wavesShear propertiesSeismic surveys

b. Identifiers/Open·Ended Terms

Los Angeles, CaliforniaShear velocitiesSan Fernando Earthquake

c. COSATI Field/Group

18. Availability Statement

NTIS

(See ANSI-Z39.18)

I--------------------"---~11-9-.-Se-c-ur-itY-CI;ss (This Report)

I

120. Se~';rity Class (This Page)

See Instructions on Reverse OPTIONAL FORM 272 (4-77)(Formerly NTIS-35)Oepartment of Commerce

~APITj\;__ S-'(:) 1c.i\'iS (i,\\'_h_'I~1 iNC.6110 EXECUTiVE BOULEVARD

SUITE 250ROCKVILLE, MARYLAND 20852

SHEAR VELOCITIES AND NEAR-SURFACE GEOLOGIES AT

ACCELEROGRAPH SITES THAT RECORDED THE

SAN FERNANDO EARTIIQUAKE

R.T. EguchiK.W. CampbellC.M. DukeA.W. ChowJ. Paternina

PRINCIPAL INVESTIGATOR: C.M, DUKE

The research reported here was supportedby the National Science Foundation, underGrant GI 44056

Any opinions, findings, conclusionsor recommendations expressed in thispublication are those of the author(s)and do not necessarily reflect the viewsof the National Science Foundation.

Earthquake LaboratorySchool of Engineering and Applied Science

University of CaliforniaLos Angeles, California

~ .., I

UCLA-ENG-7653JUNE 1976

Abstract

Thirty-three shallow geophysical surveys were conducted at sites

affected by the San Fernando earthquake of February 9, 1971. These surveys

yielded shear wave velocities and layer thicknesses down to approximately 70

feet. Geotechnical data on geology, age, lithology and depth, from several

sources, were compiled for each site.

Also contained is a summary of new field techniques that were developed

and applied during the course of the study.

PrecetiJ"109 page blank

iii

List of Figures.

List of Tables

Introduction

Procedure.

Analysis

Results.

Site Sheets.

References

Appendix A

Appendix B

Appendix C

Table of Contents

v

Page

vii

ix

1

3

5

7

21

23

25

59

63

Preceding page blank

V\

List of Figures

Page

Fig. lAo Site Locations for Los Angeles and Vicinity. . 8

Fig. lB. Site Locations for Central Los Angeles . 9

Fig. B-l. Time-Distance Curves (Asphalt - Soil). . 61

Fig. B-2. The Effect of Impact Intensity on Wave Amplitude . 62

Preceding page blank

vii

V'li

List of Tables

Table 1. Site Information. •

Table 2. Local Geology . . ••

Table 3. Layer Properties ••

ix

Page

10

13

17

Preceding page blank

x

Introduction

This report contains a compilation of refraction seismic survey and

geotechnical data on 33 sites selected within the Los Angeles, California

area. The sites were chosen on the basis of two criteria; (1) their rela­

tive closeness to strong motion accelerographs that recorded the 1971 San

Fernando earthquake, and (2) their geologic representativeness. The main

areas of concentration for these surveys were Wilshire Blvd., Downtown Los

Angeles, and Pasadena.

Using the refraction technique, shear wave velocities and layer

thicknesses down to approximately 70 feet were determined.

The previous report, by Duke et al. (1971) at D.C.L.A., provided seismic

velocity and geologic data for sites, numbered 1 through 30, in the San

Fernando earthquake area. The same basic refraction techniques used in the

previous study for measuring shear-wave velocities were utilized in the pre­

sent program conducted in the Summer of 1975. To provide continuity between

the two reports, the sequencing of site numbers in this report begins with

Site 31. Appendix A provides the results of this phase of the work.

The primary purpose of this study is to obtain accurate near-surface

shear-wave velocity data at several sites in the Los Angeles area. These data

are currently being used to correlate both seismic velocity and strong-motion

indices with local near surface site conditions.

1

Procedure

The seismic refraction technique is based upon the principle that

horizontal shear waves traveling through the ground are reflected and refracted

by soil layers of different velocity. Although other methods to determine

velocity exist, such as down-hole and cross-hole surveys, the refraction method

has the advantage of requiring less manpower and less field equipment.

The basic procedure is one that has been used previously at D.C. L.A. to

obtain geophysical site data. It consists of horizontal blows to a heavy

wooden plank from a 25-pound wooden mallet. The plank is laid out so that it

is perpendicular to the geophone line. The front wheels of an automobile

are then placed on the plank to insure maximum ground contact. The energy

pulses from the transverse shots are then picked up by horizontal geophones

which, in turn, are recorded by an oscillograph. For a more complete descrip­

tion of the technique References 3 and 4 may be examined.

In the process of conducting the present surveys, two new techniques

were examined and applied:

conducting surveys on asphaltic surfaces

examining the effect of impact intensity on records

The new techniques were examined because (1) their application would make the

surveying of an asphalt-paved site possible, and (2) they would preclude,

in some cases, the need for larger energy sources. Results are given in

Appendix B.

Preceding page blank3

+

Analysis

The records obtained in the field refraction surveys consisted of a

series of 12 traces and a time break from an oscillograph camera. The

camera recorded a time mark for every hundredth of a second.

Since most sites were noisy, it was frequently difficult or impossible

to distinguish a clear onset. As a result, for some records the first

distinguishing wave form of a trace had to be used in place of the onset.

In most cases this peak or trough was very close to the onset, and in all

cases it was as close to onset as possible. Since the frequency content of

a wave form changes with distance from the source, the velocity resulting

from using peaks or troughs will vary somewhat from that resulting from using

true onsets. However, a careful comparative study showed that the error

involved is considerably less than that involved in determining items from

the records or drawing a straight line through the corresponding points when

plotted on a travel time graph.

The points derived from the records in the above manner were plotted

on a time-distance graph. When a series of straight lines was drawn through

the plotted points, the apparent velocities of the resulting layers were

computed as the inverse of the slopes of these lines. It was estimated that

a precision of from 4 to 6 percent was obtained for the velocities. Critical

distances also were read off to the intersections of straight line segments,

with a precision estimated to be about 20 percent.

These graphs contained information from shots at both ends of the shot

line. Thus, both up-dip and down-dip apparent velocities and intercept times

were found. This information and the computerized algorithm of Mooney (1973)

yielded the thickness of each layer at both ends of the shot line and the

true layer velocities. For a more complete descripU (W' J,; « nage \l\at\~YteC8U\t\D "

in seismic surveying, see Reference 6.

5

tiques

Results

The general locations of the sites are presented in Figures lA and lB.

The sites range geographically as far north as the OSO Pumping Plant in

Gorman down to the Long Beach State University in Long Beach. Figure lA

presents a Los Angeles Vicinity map which includes those sites outside the

Downtown and Wilshire areas. Figure IB is an insert to Figure IA and locates

sites in Downtown Los Angeles and along the Wils&ire Blvd corridor. These

figures are meant to serve as general location maps. To obtain the exact

locations, the site maps in Appendix A or the corresponding map and grid

numbers of the Thomas Bros. Maps (Table 1) should be used.

General information about the location of each site is contained in

Table 1. In this table, the sites are given sequence numbers which corres­

pond to the numbers in Figures lA and IB and in the site sheets given in

Appendix A. The sequencing of site numbers begins with Site 31. A total of

33 sites were surveyed. In addition, page and grid numbers of the Thomas

Bros. Maps for Los Angeles are given. These can be used to locate the site

with respect to individual streets.

Information about the length and geophone spacing of each survey is

also contained in Table 1. The horizontal lengths range from 100 to 360 feet,

the value depending on the local site conditions. For most of the downtown

and Wilshire sites, the average length was approximately 120 to 130 feet.

Longer spreads could not be obtained because of local noise problems (i.e.,

passing traffic). For sites located away from the metropolitan area, lengths

ranging from approximately 165 feet to 360 feet were attained. In general,

the spacing of the geophones was set at 10 or 15 feet. By using the shorter

spacings, more detailed information was gained about the thinly bedded strata

close to the ground surface.

Preceding page blank7

61

-

54-

-__----40 585"6 SEE ENLARGEMENT

- OF THIS AREA

SCALE INKILOMETERS

SCALE IN MILES

o 2 4 6 810I I I , I I

o 4 8 12161'1 I I! I II !

Figure 1A. Site Locations for Los Angeles and Vicinity.

8

coE

------I-----I----~l----+--'

SCALE IN MILES012I I

012I I I I

SCALEKILOMETERS

Figure 1B. Site Locations for Central Los Angeles.

9

TABLE 1

SITENO. LOCATION

SITE INFORMATION

MAP1

NO. LOCATION

SPREADLENGTH SPACING

ft ft

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

MacArthur Park, L.A.

Ambassador Hotel, L.A.

Nor.mandie Ave. andSixth St., L.A.

Grand Ave. and ThirdPlace, L.A.

First St. and Hope, L.A.

Figueroa St. and ThirdSt., L.A.

Olympic Blvd. andValencia St., L.A.

750 S. Garland, L.A.

Von Kleinsmid Center,U.S.C., L.A.

Loma Vista Ave. and49th St., Vernon

3710 Wilshire Blvd., L.A.

Wilshire Blvd. andSpaulding, L.A.

Wilshire Bl~d. andMcCarthy Vista, L.A.

Wilshire Blvd. and PalmDr., Beverly Hills

435 Oakhurst Dr.,Beverly Hills

Santa Monica Blvd. andLinden Dr., Beverly Hills

Beverly Dr. and SuttonWay, Beverly Hills

44

43

43

44

44

44

44

44

44

53

43

42

42

42

33

42

33

A2

F2

E1

D3

D2

C2

B3

B3

/1.6

C3

E2

F2

F2

Cl

cs

Bl

B4

130

120

120

195

130

200

180

120

270

182

180

130

130

120

120

120

120

10

10

10

15

10

10

10

10

15

14

15

10

10

10

10

10

10

1These numbers and locations correspond to those listed in the Thomas Bros.Maps for Los Angeles and Orange counties.

10

TABLE 1 (Cont'd)

SITE INFORMATION

MAP SPREADSITE LENGTH SPACINGNO. r...0 CAT ION NO. LOCATION ft ft

48 D.C.L.A., Westwood 32 E6 360 30

49 Zonal St. and SanPablo St., L.A. 45 B2 130 10

50 Pomeroy St- and MarkSt., L.A. 45 A2 120 10

51 Cal Tech Athenaeum,Pasadena 27 C5 165 15

52 Cal Tech MillikanLibrary, Pasadena 27 C5 180 15

53 Cal Tech SeismologicalLaboratory, Pasadena 26 E6 100 10

54 Flintridge Riding Club,Pasadena 19 D4 240 15

55 900 S. Fremont, Alhambra 37 A5 180 15

56 Westchester Rec.Center, Westchester 56 A2 240 10

57 Malaga Lane, PalosVerdes Estates 72 D2 120 10

58 Whittier Narrows Dam 47 C6 165 15

59 Legg Lake Rec. Center 47 C5 200 15

60 OSO Pump Plant, Gorman 141 200 20

61 Pearblossom Pump Plant,PearblDssom 185 B7 220 20

62 Ocean Blvd. and CedarAve. , Long Beach 75 C5 120 10

63 Long Beach State Dniv. ,Long Beach 76 C3 130 10

11

Table 2 provides detailed descriptions of the local geology of the

sites. The geology and age were obtained from relevant geologic maps

(References 7,8,9,10,12,13) and soil logs. A description of the geologic maps

is provided in Appendix C. The lithology data were obtained directly off of

soil logs supplied by Le Roy Crandall and Associates, Los Angeles, and the

United States Geological Survey. Also obtained in this way were the thick­

nesses of fill or the depths to specified layers. Note that, in most cases,

two sets of numbers are given in Table 2. The numbers in parentheses were

taken from the geophysical surveys while the others were taken from available

soil logs. The purpose of presenting both numbers was to provide a means

of checking geophysical data with geotechnical data. In most cases, as may

be seen, the agreement was quite good.

The layer velocities and thicknesses for each site are given in Table 3.

Due to noise problems, the largest number of layers that could be detected

was four. In some cases, only the thickness of the first layer could be

defined. Note, however, that velocity information for each layer is available

despite a lack of bottom boundary information.

12

TABL

E2

LOCA

LGE

OLOG

Y

SIT

EN

O.

LOCA

TIO

N--

31M

acA

rthu

rP

ark

,L

.A.

GEOL

OGY

Fil

lo

ver

Old

All

uv

ium

ov

erP

uen

teFm

.

AGE

Ho

loce

ne

ov

erP

leis

tocen

e("

\'t'

tn.'

\>'"

TTM

";1"

'\.,.

"_

"_

....

oJ

•..I

....

..._

_~J.~

LITH

OLO

GY

Sil

t,S

and

&C

lay

ov

erS

ilts

ton

e

DEP

THI

(3')

of

Fil

l;2

0'-

30

'(3

6')

...._

n1'

::'_

Lo

U...

.U~1.J.

I..C

,L·i

ll.

32 33

Am

bass

ador

Ho

tel,

L.A

.

Nor

man

die

Ave

.an

dS

ixth

St.

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Old

All

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ium

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isto

cen

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ver

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ente

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ov

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ne

Rec

ent

ov

erO

ldH

olo

cen

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ver

All

uv

ium

ov

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leis

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ver

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ente

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U.

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cene

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t,S

and

&C

lay

ov

erS

ilts

ton

e

Sil

t,S

and

&C

lay

ov

erS

ilts

ton

e

15

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0'

(15

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0')

toP

uen

teFm

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(9')

toO

ldA

llu

viu

m;

25

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0'

(27

')to

Pu

ente

Fm.

I-'

W

34G

rand

Ave

.an

dT

hir

dP

lace,

L.A

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ldA

llu

viu

mo

ver

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nan

do

FIn.

Ple

isto

cen

eo

ver

Pli

ocen

eS

ilt,

San

d&

Cla

yo

ver

Sil

tsto

ne

(15

')to

Fer

nan

do

Fm.

35F

irst

St,

and

Hop

e,L

.A,

Com

pact

edF

ill

Ho

loce

ne

ov

ero

ver

Pu

ente

Fm.

U.

Mio

cene

Fil

lo

ver

Sil

tsto

ne

(8')

of

Fil

l

36

37 38

Fig

uer

oa

St.

and

Th

ird

St.

,L

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mpi

cB

lvd

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alen

cia

St.

,L

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750

S.

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lan

d,

L.A

.

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pact

edF

ill

ov

erO

ldA

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­vi

umo

ver

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nan

do

FIn.

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lo

ver

Old

All

uv

ium

Old

All

uv

ium

ov

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ern

and

o, FIn.

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ne

ov

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leis

tocen

eo

ver

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ocen

e

Ho

loce

ne

ov

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leis

tocen

e

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isto

cen

eo

ver

Pli

ocen

e

Sil

t,S

and

&C

lay

ov

erS

ilts

ton

e

San

dan

dC

lay

wi

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vel

San

dan

dG

rav

elly

San

do

ver

Sil

tsto

ne

(5'-

10

')o

fF

ill;

20

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0'

(20

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5')

toF

ern

and

oFr

o.

(5')

toO

ldA

llu

viu

m

15

'-3

5'

(15

')to

Gra

vell

yS

and

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er;

55

'to

Fer

nan

do

Fro

.

lNo

te:

Val

ues

rep

rese

nt

thic

kn

ess

of

fil

lo

rd

epth

tosp

ecif

ied

lay

er.

Num

bers

inp

are

nth

ese

sare

tak

enfr

omg

eop

hy

sica

lsu

rvey

s;o

thers

are

tak

enfr

omso

illo

gs.

TABL

E2

(Co

nt'

d)

LOCA

LGE

OLOG

Y

SIT

EN

O.

LOCA

TIO

N

39V

onK

lein

smid

Cen

ter,

U.S

.C.,

L.A

.

GEOL

OGY

Rec

ent

ov

erO

ldA

llu

viu

m

AGE

Ho

loce

ne

ov

erP

leis

tocen

e

LITH

OLO

GY

Sil

t&

San

dwI

Gra

vel

ov

erG

rav

elly

San

d

DEP

TH

10

'-1

5'

(15

')to

Gra

vel

lyS

and

40Lo

ma

Vis

taA

ve.

and

49

thS

t.,

Ver

non

Rec

ent

All

uv

ium

Ho

loce

ne

San

dw

lGra

vel

NA2

l-'

.j:'

-

41 42 43 44 45 46 47

3710

Wil

shir

eB

lvd

.,L

.A.

Wil

shir

eB

lvd

.an

dS

pau

ldin

g,

L.A

.

Wil

shir

eB

lvd

.an

dM

cCar

thy

Vis

ta,

L.A

.

Wil

shir

eB

lvd

.an

dP

alm

Dr.

,B

ever

lyH

ills

435

Oak

hu

rst

Dr.

,B

ever

lyH

ills

San

taH

on

ica

Blv

d.

and

Lin

den

,B

ever

lyH

ills

Bev

erly

Dr.

and

Su

tto

nW

ay,

Bev

erly

Hil

ls

Old

All

uv

ium

Com

pact

edF

ill

ov

erO

ldA

llu

­vi

um

Old

All

uv

ium

Rec

ent

ov

erO

ldA

llu

viu

m

Rec

ent

ov

erO

ldA

llu

viu

m

Rec

ent

Old

All

uv

ium

ov

erS

anta

Mon

ica

Sla

te

Ple

isto

cen

e

Ho

loce

ne

ov

erP

leis

tocen

e

Ple

isto

cen

e

Ho

loce

ne

ov

erP

leis

tocen

e

Ho

loce

ne

ov

erP

leis

tocen

e

Ho

loce

ne

Ple

isto

cen

eo

ver

Tri

ass

ic

Sil

t,S

and

&C

lay

Sil

t,C

lay

&S

and

ov

erA

sph

alt

icS

ands

Sil

t,C

lay

&S

and

ov

erA

sph

alt

icS

ands

Cla

yo

ver

Gra

vel

lyS

and

Sil

t,C

lay

&S

and

ov

erG

rav

elly

San

d

Sil

t,C

lay

&S

and

NA

NA (8')

of

Fil

l;2

5'

toA

sph

alti

cS

ands

45

'-5

0'

toA

sph

alti

cS

ands

15

'(1

0')

toG

rav

elly

San

d(V

ery

Den

se­

Old

All

uv

ium

?)

10

'-2

0'

(20

')to

Gra

vel

lyS

and

NA (3'-

11

')to

Sla

te

NA2

:N

otav

ail

ab

le.

TABL

E2

(Co

nt'

d)

LOCA

LG

EOLO

GY

SIT

EN

O.

LOCA

TIO

N

48U

.C.L

.A.,

Wes

twoo

d

49Z

on

alS

t.an

dS

anP

ablo

St.

,L

.A.

50P

omer

oyS

t.an

dM

ark

St.

,L

.A.

51C

alT

ech

Ath

enae

um,

Pas

aden

a

52C

alT

ech

Mil

lik

an

Lib

rary

,P

asad

ena

GEOL

OGY

Fil

lo

ver

Rec

ent

All

uv

ium

Dil

uv

ial

So

ilo

ver

Pu

ente

Fm.

Old

All

uv

ium

Old

All

uv

ium

Old

All

uv

ium

AGE

Ho

loce

ne

Ho

loce

ne

ov

erU

.M

ioce

ne

Ple

isto

cen

e

Ple

isto

cen

e

Ple

isto

cen

e

LITH

OLO

GY

Sil

tan

dS

and

Cla

yo

ver

Sil

t­st

on

e

NA NA NA

DEP

TH

(10

')o

fF

ill

5'-

15

'(9

'-1

6')

toP

uen

teFm

.

(10

'to

Pu

ente

Fm

.?)

NA NA

I-'

V1

53

Cal

Tec

hS

eism

olo

gic

alL

abo

rato

ry,

Pas

aden

aB

asem

ent

Com

plex

Mes

ozo

icG

ran

ite

NA

54 55 56 57

Fli

ntr

idg

eR

idin

gC

lub

,P

asad

ena

900

S.

Fre

mo

nt,

Alh

ambr

a

Wes

tch

este

rR

ec.

Cen

ter,

Wes

tch

este

r

Mal

aga

Lan

e,P

alo

sV

erd

esE

state

s

Old

All

uv

ium

Old

All

uv

ium

Old

erD

une

San

d

Old

All

uv

ium

ov

erM

on

tere

yF

m.

Ple

isto

cen

e

Ple

isto

cen

e

Ple

isto

cen

e

Ple

isto

cen

eo

ver

Mio

cene

Sil

t&

San

do

ver

Gra

vel

lyS

and

Sil

t&

San

do

ver

Gra

vel

lyS

and

Fin

eto

Med

ium

San

d

San

do

ver

Sh

ale

(14

')to

Gra

vel

lyS

and

5'-

7'

(10

'-1

5')

toG

rav

elly

San

d

(Part

iall

yC

emen

ted

Zon

eN

ear

Su

rfac

e)

(14

')to

Sh

ale

58W

hit

tier

Nar

row

sD

amR

ecen

tA

llu

viu

mH

olo

cen

eG

rav

elly

San

d(S

hal

low

Wat

erT

able

)

J-I '"

TABL

E2

(Co

nt'

d)

LOCA

LGE

OLOG

Y

SIT

EN

O.

LOCA

TIO

NGE

OLOG

YAG

ELI

THO

LOG

YD

EPTH

59L

egg

Lak

eR

ec.

Cen

ter

Rec

ent

Hol

ocen

eS

ilt

and

San

d(L

oose

San

ds)

All

uv

ium

60OS

OPu

mp

Pla

nt,

Gor

man

Rec

ent

Hol

ocen

eNA

NAA

llu

viu

m

61P

earb

loss

om

Pum

pP

lan

t,B

asem

ent

Com

-M

esoz

oic

Gra

nit

eNA

Pea

rblo

sso

mp

lex

62O

cean

Blv

d.

and

Ced

arO

ldA

lluv

ium

Ple

isto

cen

eNA

NAA

ve.

,L

ong

Bea

ch

63L

ong

Bea

chS

tate

Un

iv.,

Fil

lo

ver

Old

Hol

ocen

eo

ver

Sil

tan

dS

and

(3')

of

Fil

lL

ong

Bea

chA

llu

viu

mP

leis

tocen

e

TABL

E3

LAY

ERPR

OPE

RTI

ES

SIT

EN

O.

LOCA

TIO

NFI

RST

LAY

ERSE

CON

DLA

YER

THIR

DLA

YER

FOU

RTH

LAY

ERV

HV

HV

HV

ss

ss

31M

ar.A

rthu

rP

ark

:L

.A.

410

374

09

1280

2426

40

32A

mba

ssad

orH

ote

l,L

.A.

990

1625

00

33N

orm

andi

eA

ve.

and

620

911

6018

2790

Six

thS

t.,

L.A

.

34G

rand

Ave

.an

dT

hir

d88

02

1110

1313

70P

lace,

L.A

.

35F

irst

St.

and

Hop

e,L

.A.

no8

1260

36F

igu

ero

aS

t.an

dT

hir

d59

08

870

2614

20I-

'S

t.,

L.A

.-..

.J

37O

lym

pic

Blv

d.

and

510

510

2012

1530

13

1980

Val

enci

aS

t.,

L.A

.

3875

0S

.G

arla

nd

,L

.A.

1000

1519

80

39V

onK

1ein

smid

Cen

ter,

790

1517

1024

2310

U.S

.C.,

L.A

.

40Lo

rna

Vis

taA

ve.

and

870

1613

9032

2000

49

thS

t.,

Ver

non

4137

10W

ilsh

ire

Blv

d.,

L.A

.10

4012

1250

42W

ilsh

ire

Blv

d.

and

630

810

30S

pau

ldin

g,

L.A

.

43W

ilsh

ire

Blv

d.

and

820

914

80M

cCar

thy

Vis

ta,

L.A

.

TABL

E3

(Co

nt'

d)

LAY

ERPR

OPE

RTI

ES

SIT

EN

O.

LOCA

TIO

NFI

RST

LAY

ERSE

CON

DLA

YER

THIR

DLA

YER

FOUR

THLA

YER

VH

VH

VH

Vs

ss

s

44W

ilsh

ire

Blv

d.an

d10

0010

1610

Pal

mD

r.,B~verly

Hil

ls

4543

5O

akh

urs

tD

r.,

600

878

015

1600

Bev

erly

Hil

ls

46S

anta

Mon

ica

Blv

d.an

d56

013

830

2114

70L

ind

enD

r.,

Bev

erly

Hil

ls

47B

ever

lyD

r.an

dS

utt

on

960

728

60W

ay,

Bev

erly

Hil

ls

48U

.C.L

.A.,

Wes

twoo

d44

010

880

2211

7044

1700

~

49Z

onal

St.

and

San

590

1316

90(X

l

Pab

loS

t.,

L.A

.

50P

omer

oyS

t.an

dM

ark

890

928

60S

t.,

L.A

.

51C

alT

ech

Ath

enae

um,

Pas

aden

a86

09

1200

1113

80

52C

alT

ech

Mil

lik

an98

017

1270

Lib

rary

,P

asad

ena

53C

alT

ech

Sei

smo

log

ical

2670

3442

10L

abo

rato

ry,

Pas

aden

a

54F

lin

trid

ge

Rid

ing

Clu

b,

850

1419

00P

asad

ena

5590

0S

.F

rem

ont,

Alh

ambr

a84

01

116

70

TABL

E3

(Co

nt'

d)

LAY

ERPR

OPE

RTI

ES

SIT

EN

O.

LOCA

TIO

NFI

RST

LAY

ERSE

CON

DLA

YER

THIR

DLA

YER

FOU

RTH

LAY

ERV

HV

HV

HV

ss

ss

56~'!estchester

Rec

,8<

W21

2000

Cen

ter,

Wes

tch

este

r

57M

alag

aL

ane,

Pal

os

1000

1418

50V

erde

sE

state

s

58W

hit

tier

Nar

row

sD

am10

5017

1840

59L

egg

Lak

eR

ec.

Cen

ter

520

867

018

820

60OS

OPu

mp

Pla

nt,

Gor

man

560

1274

034

1190

61P

earb

loss

om

Pum

pP

lan

t,13

809

3930

I-'

Pea

rblo

sso

m'-

0

62O

cean

Blv

d.

and

Ced

ar10

007

1310

Av

e.,

Lon

gB

each

63L

ong

Bea

chS

tate

Un

iv.,

500

310

0012

1980

Lon

gB

each

Site Sheets

The results of the analysis of each site are displayed on site sheets

found in Appendix A. A master sheet is presented at the beginning of the

Appendix which graphically describes and explains the information contained

on each sheet.

Each site sheet contains both a map and a section. The map positions

the shot line with respect to major streets and landmarks in the area. The

section displays the subsurface stratification along the shot line (A-B) as

determined from the surveys. The layer depths at both ends of the section

were determined from the analysis previously described, which assumes straight

line boundaries between layers. The shear-wave velocities are inserted in

the corresponding layers.

There were some sites where the velocity boundary of the next layer was

detected on only one end of the survey line. It was thought that this

information, although partial, would provide useful data and therefore it was

included. From this limited data a horizontal layer boundary could be

estimated. This boundary is represented on the site sheets by dotted line

interfaces.

Preceding page blank21

References

1. Bolt, B.A., W.L. Horn, G.A. MacDonald and R.F. Scott, Geologic Hazards,Springer Verlag, New York (1975).

2. Chase, G.W., and Chapman, R.H., "Black-Box Geology," CaliforniaGeolog~, CDMG, January 1976, pp. 8-12.

3. Duke, C.M., "Techniques for Field Measurement of Shear Wave Velocityin Soils," Proceedings Fourth World Conference on Earthquake Engineering,Santiago, 1969, pp. 39-54.

4. Duke, C.M., Johnson, J.A., Kharraz, Y., Campbell, K.W., and Malpiede,N.A., "Subsurface Site Conditions in the San Fernando Earthquake Area,"San Fernando, California, Earthquake of February 9, 1971, Vol I, Part B,U.S. Dept. of Commerce, 1973, pp. 785-799.

5. Eguchi, R.T., "An Earthquake Risk Hodel that Incorporates Local NearSurface Site Conditions," Mechanics and Structures Dept., University ofCalifornia, Los Angeles, UCLA-ENG-7547, 1975.

6. Heiland, C.A., Geophysical Exploration, Prentice-Hall, Inc., New York,1940, pp. 1013.

7. Jennings, C.W., and Strand, R.B., Map, Los Angeles Sheet, CDMG,Sacramento, 1969.

8. Jennings, a.p., Map, Long Beach Sheet, CDMG, Sacramento, 1962.

9. Jennings, a.p., Map, San Bernardino Sheet, CDMG, Sacramento, 1969.

10. Lamar, D.L., "Geology of the Elysian Park-Repetto Hills Area, Los AngelesCounty, California," Special Report 101, CDMG, Sacramento, 1970.

11. Mooney, Harold M., "Handbook of Engineering Geophysics," Bison Instru­ments, Inc., Minneapolis, Minn., 1973.

12. Poland, J.F., Garrett, A.A., and Sinnott, A., "Geology, Hydrology, andChemical Character of Ground Waters in the Torrance-Santa Monica Area,California," Geological Survey Water-Supply Paper 1461, USGS, 1959.

13. Poland, J.F., Piper, A.M., and others, "Ground-Water Geology of theCoasta,l Zone Long Beach-Santa Ana Area, California," Geological SurveyWater-Supply Paper 1109, USGS, 1956.

14. Power, J.H., and Real, C.R., "Shear Have Velocity-Progation and Measure­ment,'1 California Geology, CDHG, Sacramento, February 1976, pp. 27-29.

Preceding page blank23

NO. *

APPENDIX A

MASTER SITE SHEET

SITE: NAME AND GENERAL LOCATION OF SITE

~ 1 1 1_____

SHOTLlNy .A

I I 0 200 FEET

'I'iiiiiiiiiiiil!~~i

IITRUE NORTH

GEOLOGIC SECTION TAKEN FROMTHE SHOT LINE A TO B

A

SECTION

DISTANCE ALONGSHOT LINE IN FEET

o 60 120 180 240 300o r--....,.------rl-..........-----,-I-~_""""TI-..,..---I....---r--r--I...... 0 B

DEPTH INFEET

Vs = - 60

~ • •• • • • • ••••••••••• • ••••• • • • • ••~~~~~I~~·7··..~ 80

80 -

20 ~--~;~~~~=VS::=7-----------j-2040 - VELOCITY ./ - 40INTERFACE-./

60 _ (SH)

SECTIOI\ILETTERS,FOUND ONSHOT LINEABOVE

v =s INTERFACE FORTHOSE LAYERS WHEREONLY ONE sIDeCOULD BE DETECTED

* SITE NUMBER CORRESPONDS TONUMBERS FOUND IN TABLE 1AND ON SITE LOCATION MAPS

DATE: DATE OFFIELD WORK

25Preceding page blank

SITE: MAC ARTHUR PARK, L.A.

B

A

NO. 31

N

~IWILSHIRE BLVD

SECTION

o 200 FEET

740 fns

100 120B

25 ~ 1280 fps -••••••••••••••••••••••••••••••••••••••••••••••••••• 4

50 ......2640 fps

26

-

DATE - JULY 1975

NO. 32

SITE: AMBASSADOR HOTEL, L.A.

,__ILWILSHiRE BOULEVARD

o 200 FEET

I­wwex:I­en«z-l«~(J

Nr---1/8IA

7th STREET

1SECTION

50 100 120I I I B

990 fps

2500 fps -25 .-

oA 0 r--..,..-......---r--.-""-OOOYO---'---'-__"",-"""",,__

50- -

DATE - AUG. 1975

27

NO. 33

SITE: NORMANDIE AVE. AND SIXTH ST., l.A.

L5th St

A B Ww> >« «w wa: C0 z:E «C :iEa: 0::, « 0z

0 200 FEET N

II6th St

II120

A

SECTION

o 50 100O,..--r---r---r----,r-.,..--,--.....,.---r----,r-or---r--w

I I I , 1620 fps I I

1160 fps25 ..

B

50-

2790 fps

-

DATE - AUG. 1975

28

NO. 34

SITE: GRAND AVE.AND 3RD PL., L.A.

o

I

200 FEET

N

SECTION

0 50 100 150 195A 0 B

L 880 f~sI I

1110 fps

25 ~1370 fps -

50 I- -DATE - JULY 1975

29

NO. 35

SITE: 1st. ST. AND HOPE ST., l.A.

N

, go 200 FEET

A

SECTION

o 50 100 130O...---r---w--.....---......--...-~--r"~-....-..-__-....--..

I 1 720 fps I 1 I I I I 1 IB

25 f-

50 '-

1260 fps -

-

DATE - JULY 1975

30

NO. 36

SITE: FIGUEROA ST. AND 3RD St., l.A.

o 200 FEET

N

SECTION

0 50 100 150 200A 0 • I • • ! T 590 f~S • 1 • • I -.- B

r-. 870 fps25 ~ -

1420 fps -50 '- -

DATE - FEB. 1975

31

NO. 37

SITE: OLYMPIC BLVD. AND VALENCIA ST., l.A.

(

o 200 FEET

SECTION

B- N

I I , I I I 510fps ' I I

1020 fps

- 1530 fps -1980 fps

- -

oA 0

25

50

50 100 150 180B

DATE - FEB. 1975

32

SITE: 750 S. GARLAND AVE., L.A.

7th STREET

w::::>zw>«c2: A B«..Ja::«Co:)

N

NO. 38

,

8th STREET0 200 FEET

SECTION

0 50 100 120A 0 I I I I B

1000 fps

:!5 ~1980 fps -

!;O ~

33

-

DATE - AUG. 1975

NO. 39

SITE: VON KlEINSMID CENTER, U.S.C., l.A.

w>«>I-Cf.lII:w>Z:::>

VON KlEINSMID CENTER

A-------B

N

Ao

o

o

50 100 150I I I I I I I I, T T, I

790 fpsI

200 FEET

200 250 270I I I I I I I I B

25 I-

50 ~

1710 fps

2310 fps

34

-

-

DATE - SEPT. 1975

NO. 40

SITE: LOMA ViSTA AVE. A~O 49TH ST•• VER~O~

__-IDISTRICT BOULEVARD

N

\\iiSiiiiiii";;;l.!!!!!!l!! u.i() 200 fEET ~

~ -====4am:fS~;;;;:;-------...A ~ 1r- ..::4~8T~H~..:S~T:!:R~E:!:E~T~=====-

o..J

aI 1~49TH~STREET~

Se.Cl\ON

Ao

o 'T • 'T

50, 1

150 182• 1 ...... .,. B

-1390 fps

2000 ips

5ll "' ..

261-'

DATE.: SEPT .1976

35

NO. 41

SITE: 3710 WILSHIRE BLVD., l.A.

WILSHIRE BLVD.

N

w>«o:2:«a::a:wCI)

3710

w

~oa:ou..Xo

B A,

7th ST. 0 200 FEET

~ I l ISECTION

180B

00 50 100 150.-....,--,....,--'-.'-r--.'--'-.'--I..--....'-'--,-s..--.....-,--,-,--.1040 fps

A

25 r- 1250 fps -

50 ~ -

DATE - AUG. 1975

36

NO. 42

SITE: WILSHIRE BLVD. AND SPAULDING AVE., LA.

fiiiiiiiiiiiii-~~o 200 FEET

WILSHIRE BOULEVARD

A

IB

IN

SECTION

130B

o 50 100o r--..,.I---,I-y---r--...,I----.----r---,.I---.~~l630 fps

A

25 ~1030 fps -

50 L -

DATE - AUG. 1975

37

NO. 43

SITE: WILSHIRE BLVD. AND McCARTHY VISTA, l.A.

WiLSHIRE BOULEVARD

N

7/WARNER DRIVE

o 200 FEET

SECTION

130B

o 50 100O..--_~--.---.,r---r-.....--....,.,.--,r---.,..--.,--r---'II

, 1 820 fps I •A

25 ,.... 1480 fps -

50 ..... -

DATE - AUG. 1975

38

NO. 44

SITE: WILSHIRE BLVD. AND PALM DR., l.A.

WILSHIRE BOULEVARD

w>

w c:>------0a:S-Ar--1-o I I ~

liiiiiiiiiiii~-!!!!!!!!!J :5 I I ~o 200 FEET ~ I I ~

II 0

N

SECTION

120o 50 100A 0 ~__...,.....--r--.-r--I-'--""""'--'----'-"'--I""'-_

1000 fpsB

25 -

50 -

1610 fps-

-

DATE - AUG. 1975

39

NO. 45

SITE: 435 OAKHURST DR.• BEVERLY HILLS

B

A

o 200 FEET

BEVERLY BOULEVARD

N

I ISECTION

0 50 100 120A 0

1600 fps I B

780 fps

25 f-1600 fps

50 l- -

DATE - FEB. 1975

40

ItIN

NO. 46

SITE: SANTA MONICA BLVD AND LINDEN DR., BEVERLY HILLS

o 200 FEET

SECTION

0 50 100 120A 0 B

560 fps

25

501470 fps

DATE - AUG. 1975

41

NO. 47

SITE: BEVERLY DR. AND SUTTON WAY, BEVERLY HillS

B

A

SUTTON WAY

;200 FEET

N

A

SECTION

o 50 100o ..............--.---.-.....-....I--,960-fps' , I '

2860 fps

25 I-

50 .....

42

120B

-

-

DATE - AUG. 1975

NO. 48SITE: U.C.LA. ATHLETiC F!ElD, WESTWOOD

TRACKSTADIUM

B----.......----A

L- ---I -+ _

t+IN

PAULEY

PAVILLION

FOOTBALL Fi ELD

o 200 F~ET

-II

I0 50 100

A 0 • i • I i i 6 I I

25 -

i

50 I75L

10J

SECTION

150 200 250 300I 440'fps l iii Iii i , Iii

880 ips

1170 fps

1700 fps

43

STRATHMORE DRIVE

360

-

-DATE - SEPT. 1975

NO. 49

SITE: ZONAL ST. AND SAN PABLO ST.,l-A.

I­ww0:I­(J)

o..J00<CQ.

Z<C(J)

A---BN

ZONAL STREET

o 200 FEET

SECTION

120B

o ~ 100o r--'"T.-,.--,-r---r--r

I-,.---r----r---r---"r--.,......."r---1

590 fpsA

25 ~ 1690 fps -

50 '- -

DATE - AUG. 1975

44

NO. 50

SITE: POMEROY ST. AND MARK ST., L.A.

t

N

o 200 FEETSECTION

120B

o 50 100A 0 .r--....--r---.----..,-..--,----.----.,r--..---,...,.--.,

890 fps

25 '-2860 fps -

50 '- -

DATE - AUG. 1975

45

NO. 51

SITE: CALTECH ATHENAEUM, PASADENA

ATHENAEUM

o =

N

200 FEET

oA

B

CALIFORNIA BLVD

SECTION

Ii

o 50 100 150 165o r-""I',-r-,""",-..-,-r,--"..-.....--r-........-.,I..--r,-.....-.TU--,U...--'T1--,u,.....

860 fps

1200 fps

25 /-

50 '-

1380 fps

46

-

-

DATE - AUG. 1975

NO. 52

SiTE: CALTECH MILLIKAN LIBRARY, PASADENA

I Iw>.<3::zoen-l

s:I

NMILLIKANLIBRARY

B A~ ~

6 G!

~0 200 FEET

CALI FORNIA BLVD

I ISECTION

0 50 100 150 180A 0 I I I • B

980 fps

25 ~ -1270 fps

50 '- -

DATE - AUG. 1975

47

NO. 53

SITE: CALTECH SEISMOLOGICAL LABORATORY, PASADENA

A B(SEIS_ILAB.

N

,0 200 FEET

SECTION

0 50 100A 0 I I I I I I I I I B

2670 fps25 I- -

50 ...... 4210 fps -

DATE - AUG. 1975

48

NO. 54

SITE: FLINTRIDGE RIDING CLUB, PASADENA

N

JETPROPULSIONLABORATORY

200 FEETo

~•••••••••••••• ••••••••••••••••••••••••••••••••••••• 8 ••••••••••• a=

c 0«~ B A ~o 0~ g> FLINTRIDGE ~

RIDING CLUB d

SECTION

240B

20015010050oA 0 r-r--r"""T"""--r-T--r"""T"""--r-T--r"""T"""T""'1r-T-"-"""T"""--T"""T-"-~

850 fps

25 1900 fps

50

DATE - AUG. 1975

49

NO. 55

SITE: 900 S. FREMONT AVE., ALHAMBRA

900

w

~I­Zo~wa:u.

A-----B

ORANGE

N

,0 200 FEET

SECTION

0 50 100 150 180A 0 I I I I I I I I I I I I I I B

840 fps

25 -. 1610 fps -

50 ....

50

-

DATE - AUG.1915

NO. 56

SITE: WESTCHESTER RECREATION CENTER, WESTCHESTER

MANCHESTER AVE

A

B

N,0 200 FEET

SECTION

0 50 100 150 200 240A 0 . . I I . I . I B

890 fps

25 -2000 fps

50 -- -

DATE - AUG. 1975

51

NO. 57

SITE: MALAGA LANE, PALOS VERDES ESTATES

--J%\L-T-E-JO-N---------

v,~ %0 l-:=J8 LANE ---------

_MA~Gl r----/;:-B

N

o 200 FEET

SECTION

o 50 100 120o r--"-r,-,r--'T""""",...,--r--t~""T"""--r--,r--~I"TI---'

1000 fps

25 I-

50 I-

52

1850 fps -

-

DATE - SEPT. 1975

NO. 58

SITE: WHITTIER NARROWS DAM

o

SECTION

0 50 100 150 165A 0 ,

I,

I I B

1050 fps

25 1840 fps -

50 I- -

200 FEET

DATE - SEPT. 1975

53

NO. 59

SITE: LEGG LAKE REC. CENTER

LEGG LAKEREC. CENTER

B""A

N•0 200 FEET

SECTION

0 50 100 150 2000 I • • 520'fps' I • I ,

670 fps25 I- -

820 fps

50 ..... -

DATE - SEPT. 1975

54

NO. 60

SITE: osa PUMPING PLANT, GORMAN

N

//

//

//

//

//

//

/

SECTiON

A

/B

o 500 FEET

o 50 100 150 200A 0 r--"-,.--r-r---.,-r---"-..,--r-,.-,.,--,...--r----.-1r---,.-...,...-,...--.-. ......., B

560 fps

25 r-740 fps -

50 ~ •••••••••••••••••••••••••••••••• ;;.~~.~~;••••••••••••••••••••••••••••••••••~

DATE - SEPT. 1975

55

NO. 61

SITE: PEAR BLOSSOM PUMPING PLANT, PEARBLOSSOM

PEARBLOSSOM HIGHWAY

N

\ ,, I\ ,, I\ I\ \\ );> I\g,\~\\ ~\'-q\ \\ \\ \

PUMPINGPLANT --M-li

:~-=rJ'

o 500 FEET

SECTION

220B

o 50 100 150 200o .--.....-...,'.--.....-........-...-1........--.-.......,•.--..,...........1-................--.---.,--,...-1...,•.--..,............-,...-.....,-,...-.,·

1380 fpsA

25 --3930 fps

-

50 '- -DATE - SEPT. 1975

56

NO. 62

SITE : OCEAN BLVD. AND CEDAR AVE., LONG BEACH

LBROADWAY

w>«I­::lZl­(/)w:I:U

'W>«a:«CiwUB",

A

lrN

OCEAN BLVD

I I I

0 200 FEET

SECTION

0 50 100 120A 0 B

1000 fps1310 fps25

50

DATE - AUG. 1975

57

NO. 63

SITE: LONG BEACH STATE UNIV.

~I '--

ATHERTON STREET

IIIII w

>

tI ~I i w

I I 0I I a::

I I w0 A I I >

t3 0I I I ..Jco !!-1 I.. -" «a::. "

Q..

UJ ---,.. \~ I \..J i Nu....J i..JUJ I r---co

I ~ \" - ---, 'I I II I I ,I I

iI I 0 1200 FEETI II

~7TH STREET

~

SECTION

0 50 100 130A 0 B

L 500 fps 1000 fps

25 /- 1980 fps -

50 ~ -DATE - AUG. 1915

58

APPENDIX B

NEW TECHNIQUES IN FIELD MEASUREMENT

The conducting of refraction surveys has been largely restricted to

those sites where ample space and bare ground were available. However, many

sites exist where the space is available, but where a survey could not be

conducted due to the existence of some type of asphaltic surface. To deter­

mine the feasibility of performing a refraction survey on a paved site, a

comparative study was performed on the U.C.L.A. campus. Two sets of geophone

lines were set up, one on asphalt and the other on soil. These lines were

parallel to each other and had a separation of fifty feet between them. For

the paved site, the geophones were simply placed on the pavement. For the

soil site, the geophones were spiked into the ground.

Two sets of records were then obtained and time-distance curves plotted

to represent them, Figure B-1. The arrival times were identical beyond the

first three geophones. However, there existed some difficulty in interpreting

the first three arrivals for the paved site. This was apparently due to the

occurrence of two direct waves. The first direct wave, possessed a

velocity much too high for the underlying soil (the soil logs were examined).

It is believed that this first velocity was the shear-wave traveling through

asphalt. This is conceivable since the shear wave velocity is larger for

asphalt than for soil. The second direct wave for the first 3 geophones on

the paved site, however, had a slope equal to that of the adjacent soil site

and consequently had the same shear-wave velocity. This can be seen in Figure

B-l.

Therefore, with careful interpretation, supplemented with available geo­

technical data, surveys at six other sites were conducted on asphalt: Sites

41, 51, 53, 55, 57, and 61.

59

.25

.20

- -- ASPHALT--- SOIL

IUCLA ATHLETIC FIELD I .25

.20

.05DIRECT WAVE TRAVELINGTHROUGH ASPHALT

.05

u .15 .15 uw w~ ~w w~ ~

I- .10 .10 I-

oll::::::::::...-----l..-----....L.-----L-----==:::ilIIoo 45 90 135 180

DISTANCE (FT)

Figure B-1. Time-Distance Curves (Asphalt - Soil).

60

To examine the effect of impact intensity on the shape and amplitude of

a record, a series of hits was made with the 25 lb. hammer using varying

intensities. These intensities ranged from soft golf type putts to hard

baseball type swings. Although the study was not conducted quantitatively,

the results generally showed that beyond a certain threshold intensity, a harder

hit provided no increase in amplitude, Figure B-2. A possible reason for this

is that the additional energy produced by a harder hit was lost in the slippage

of the plank. Experience showed that a hard hit displaced the plank by as

much as an inch. Although this is not a desirable quality in general, in

many cases it is not a hindrance. One such case would be a site where the

rock is encountered at a relatively shallow depth. Here, a larger energy

source will not, in general, provide any additional information beyond the

direct wave velocity.

However, for most sites, the loss in energy will often hinder the

acquisition of much needed information. By devising a method to eliminate

this loss, one could obtain records with clearer onsets resulting in less

ambiguity in interpretation. A possible procedure to eliminate this loss

would be to line the bottom of the plank with a corrugated surface. This

would provide additional friction to resist board movement while assuring

that the amplification of P-waves remains TIlinima1. A heavier weight on the

plank might also help. More study is needed, however, before this procedure

can be implemented.

61

w>I­<!I-...l<!:::lowCl:::lI-..J0...:?E<!wUic::(c::I-

• •

• •

HAMMER INTENSITY (NOT TO SCALE)

Figure 8.-2. The Effect of Impact Intensity on Wave Amplitude.

62

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