2- 9gmw.consrv.ca.gov/shp/apsi_siteinvestigationreports_ocr/... · 1986-09-04 · commissioners...

STATE OF CALIFORNIA-THE RESOURCES AGENCY

DEPARTMENT OF CONSERVATION

DIVISION OF MINES AND GEOLOGY BAY AREA REGIONAL OFFICE

380 CIVIC DRIVE, SUITE 100

PLEASANT HILL, CA 94523-1997

PHONE, (415) 646-5920

ATSS 599-5920

Mr. J.W. Cobarrubias Staff Geologist Building and Safety City of Los Angeles 411 City Hall Los Angeles, CA 90012-4869

Dear Joe:

2- I I 9 GEORGE DEUKMEJIAN, Go..,mor

April 18, 1988

We are placing on open file the following reports, reviewed and approved by the City of Los Angeles, in compliance with the Alquist-Priolo Special Studies Zones Act:

Geologic & soil engineering review, Tent. Tract 43969 (portion of Tent. Tract-40330), Porter Ranch, 20,000 Sesnon Blvd., Northridge, CA; by Geosoils, Inc.; Dec. 21, 1987; with addenda of March 8 & 21, 1988.

Geologic & Seismic investigation, proposed commercial addition, Lot V-- 4, Tract 22350, 12835 Arroyo st., Los Angeles, CA; by Geo/Systems,

Inc.; 9/4/86; with letter of 1/6/88.

Addendum to soils & engineering geologic investigation for portion Lot 114, Western Empire Tract, 11460 Big Tujunga Canyon Ave., Los Angeles, CA; by Geo/Systems,, Inc.; 2/3/88.

Prelininary geologic,, soils, engineering and seismicity investigation, Tent. Tract 45349 (17900 Sesnon Blvd.), Granada Hills, CA; by Geosoils, Inc.; 10/28/87; with addendum of 12/3/87 and revision of 1/25/88.

Seismic investigation, preliminary parcel maps, portion Lot 52, Tract 7911 (PM 6040), 6527 Takay Road, Tujunga, CA; by Triad Foundation Engineering, 12/15/87; with accessory report of 2/9/88.

EWH:rfq cc: A-P file (5)

Sincerely yours,

Earl w. Hart, CEG 935 Senior Geologist &

Program Manager

COMMISSIONERS

BENITO A. SINCLAIR PRE'.SIOENT

REVELACION P ABRACOSA VtCE•F'RESIOE:NT

RICHARD W. HARTZLER MARCIA MARCUS

TOM WOO

ADVISORY BOARD MEMBERS

PATRIC D MAYERS PAE:SIOENT

ROBERT B BURKE V1CE-PAES10ENT

IRWIN H GOLDENBERG DIANE MUNIZ "'ASILLAS

DR. DOROTHY M TUCKER

JAN BEAR SECR~"rARY

Mr. Earl Hart

C1Tv OF Los ANGELES CALIFORNIA

TOM BRADLEY MAYOR

April 6, 1988

Calif. Division of Mines and Geology 380 Civic Drive, Suite 100 Pleasant Hill, CA 94523-1997

DEPARTMENT OF

BUILDING AND SAFETY

4 1 1. CITY HALL

LOS ANGELES. CA 90012·4869

FRANK V. KROEGER GEN£.R.A.l,. MANAGER

WARREN V. O"BRIEN S:XE:CUTIVE OFFICER

DEPUTY GENERAL MANAGERS

K. ROBERT AYERS ~OBERT J. PICOTT EARL SCHWARTZ TIMOTHY TAYLOR

SUBJECT: Geologic-Seismic Study for Lot 4 of Tract 22350, located at 12835 ARROYO STREET. Geologic Seismic and Soil Engineeering Reports No. GS86-769, dated September 4, 1986 and March 1, 1988, prepared by California GeoSystems, Incorporated

The above geologic-seismic reports concerning the assessed potential seismic conditions at the project location have been reviewed by the Grading Division of the Department of Building and Safety. The property is located within a Fault Area identified by the State of California Special Studies Zones (established under Chapter 7.5, Division 2 of the Public Resources Code, i.e., Alguist-Priolo Act).

On the basis of the findings presented in the reports and the subsurface exploration conducted on the site, the reports are acceptable with the following conditions:

See Attached Letter

JAMES D. KAPRIELIAN Chief of Grading Division

J. W. COBARRUBIAS J 0 J1 ,r Staff Geologist, Building and Safety (213) 485-2160

TDN:gas TGRMG040688B/2GR

Attachments: Geologic-Seismic Report Department Review Letter

AN EQUAL EMPLOYMENT OPPORTUNITY - AFFIRMATIVE ACTION EMPLOYER

CtTY OF Los ANGELES COMMISSIONERS

BENITO A. SINCLAIR PR~SIOl!NT

REVELACION P ABRACOSA VICC:·PRE510~N"r

RICHARD W. HARTZLER MARCIA MARCUS

TOM WOO

ADVISORY BOARD MEMBERS

PATRIC D MAYERS F'~E.SIOE.NT

ROBERT S BURKE v1c1::.PR£:SIDENT

IRWIN H. GOLDENBERG DIANE MUNIZ PASILLAS

DR DOROTHY M TUCKER

JAN BEAR SE.CR£.iARY

Franco Donato 101 North Maclay Street San Fernando, CA 91340

TRACT: LOT:

22350 4

CALIFORNIA

TOM BRADLEY MAYOR

April 6, 1988

LOCATION: 12835 ARROYO STREET

DEPARTMENT OF

BUILDING AND SAFETY

41 1. CITY HALL

LOS ANGELES. CA 90012·4669

FRANK V. KROEGER GENE"RAI.. MANAGE"R

WARREN V. O'BRIEN EXECUTIVE'. OFFICE.~

DEPUTY GENERAL MANAGERS

K. ROBERT AYERS ~OBERT J. PICOTT EARL SCHWARTZ TIMOTHY TAYLOR

Log # 3743

Geological-Seismic and Soil Engineering Reports No. GS86-769, dated September 4, 1986; January 6, 1988; and March 1, 1988, prepared by California GeoSystems, Incorporated.

The above reports concerning the proposed construction of a one story on grade addition to a commercial structure have been reviewed by the Grading Division of the Department of Building and Safety.

The above geologic-seismic reports concerning the a~sessed potential seismic conditions at the project location have been reviewed by the Grading Division of the Department of Building and Safety. The property is located within a Fault Area identified by the State of California Special Studies Zones (established under Chapter 7.5, Division 2 of the Public Resources Code, i.e., Alquist-Priolo Act).

On the basis of the findings presented in the reports and the subsurface exploration conducted on the site, the reports are acceptable with the following conditions:

1. The geologist and soils engineer shall review and approve the detailed plans prior to issuance of any permits. This approval shall be by signature on the plans which clearly indicates that the geologist and soils engineer have reviewed the plans prepared by the design engineer and that the plans include the recommendations contained in their reports.

2. All graded slopes shall be no steeper than 2:1.

AN EQUAL EMPLOYMENT OPPORTUNITY-AFFIRMATIVE ACTION EMPLOYER

12835 Arroyo Street April 6, 1988

3. All recommendations of the report which are in addition to or more restrictive than the conditions contained herein shall be incorporated into the plans.

4. A copy of the subject and appropriate referenced reports and this approval letter shall be attached to the District Office and field set of plans. Submit one copy of the above reports to the Building Department Plan Checker prior to issuance of the permit.

5. All existing fill, soils, exploratory trench backfill, seismically unstable alluvium and earth materials shall be removed and recompacted under the direct supervision of the soils engineer.

6. All man-made fill shall be compacted to a minimum of 90 percent relative compaction as required by Code Section 91. 7006 (d).

7. All roof and pad drainage shall be conducted to the street in an acceptable manner.

8. The addition shall be supported on footings founded in firm alluvium or compacted fill.

9. The geologist or soils engineer shall inspect the excavations for the footings to determine that they are founded in the recommended strata before calling the Department for footing inspection.

JAMES D. KAPRIELIAN Chief of Grading Division

~j)Jf~ THEODORE D. NICKERSON Engineering Geologist

TDN/JAM:gas TGRSGL040688F/2GR (213) 485-2160

cc: GeoSystems H. Bahrke VN District Off ice

'l_/ J /? .1J"~ i~~

JEFFREY A. MOORE Structural Engineering Associate

Califorr~laj /.

OED/ SYSTEMS. INC. GEOTECHNICAL CONSULTANTS

Franco Donato 101 N. Mcclay St. San Fernando, CA 91340

January 6, 1988 GS86-769-1

Subject: Response to Los Angeles City Review Sheet dated December 2, 1987

Reference: 1) Geologic and Seismic Investigation for the Proposed Commercial Addition to Existing Structure, Lot 4, Tract 22350, 12835 Arroyo St., Los Angeles, CA; California Geo/Systems, Inc., GS86-769, dated September 4, 1986

2) Los Angeles City Review Sheet dated December 2, 1987

This letter presents our response to the referenced

review sheet dated December 2, 1987. According to the

review sheet, District Map No. 7686 shows the trace of a

surface fault rupture through the northern corner o{ the lot

and through the proposed building area. Our review of

District Map No. 7686, conducted with the assistance of Los

Angeles City cartographer Frankie A. Smith, confirms this.

Our review of the San Fernando Quadrangle Alquist-

Priolo Zone Map (Plate 1) and the Geologic Map of the San

Fernando Earthquake Area (Plate ~' however, indicates the

surface fault rupture to be just off-site from the northwest

corner of the property. In addition, detailed logging of

312 WESTERN AVENUE • GLENDALE, CALIFORNIA 91201·2836 • (818) 500·9533

1-6-88 12835 Arroyo St.

Page 2 GS86-769-l

our trenches excavated in the northwest corner of the site

do not indicate the presence of surface fault rupture.

Based on the results of the exploration presented in

our report dated September 4, 1986, our review of the

referenced published geologic maps of the area, and the fact

that surface fault rupture shown on District Map No. 7686

does not correlate with that shown on the Alquist Priolo

Special Studies Zone Map of the San Fernando Quadrangle, it

remains the opinion of this firm that surface fault rupture

does not extend onto the subject site.

Please call if you have any questions.

CALIFORNIA GEO/SYSTEMS, INC.

~R~ David B. Ebersold Project Geologist

DBE:RMR/rks

)¢/. Ramirez,

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GE/ SYSTEMS, INC.

GEOTECHNICAL CONSULTANTS 312 WESTERN AVE.

GLENDALE. CA 91201 (8, 8) SOQ.9533

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GEOTECHNICAL CONSULTANTS 312 WESTERN AVE.

GLENDALE, CA 91201 (818) 500.9533 DATE: JAN. 16100 G86b-7bq- I PLATE~

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I California;/.

I GEO/ SYSTEMS. INC. GEOTECHNICAL CONSULTANTS

I I I I I I I I I I I I I I I I I

GEOLOGIC AND SEISMIC INVESTIGATION FOR THE PROPOSED COMMERCIAL ADDITION

TO EXISTING STRUCTURE LOT 4, TRACT 22350 12835 ARROYO STREET

LOS ANGELES, CALIFORNIA

9-4-86 GS86-769

FOR

FRANK DONATO 101 N. McCLAY

SAN FERNANDO, CA 91340

312 WESTERN AVENUE • GLENDALE, CALIFORNIA 91201-2836 • (818) 500-9533

I Callfomlj f.

I ~i::01svsTEMS. '"c. GEOTECHNICAL CONSULTANTS

I I I I I I I I I I I I I I I' I I

GEOLOGIC AND SEISMIC INVESTIGATION

FOR THE PROPOSED COMMERCIAL ADDITION

TO EXISTING STRUCTURE

LOT 4, TRACT 22350

12835 ARROYO STREET

LOS ANGELES, CALIFORNIA

INTRODUCTION

A geologic-seismic investigation, requested by Mr.

Franco Donato, has been completed for Lot 4, Tract 22350

located at 12835 Arroyo Street, Los Angeles, California.

This investigation was completed to fulfill the requirements

of the Alquist-Priolo Special Studies Act of 1972. Subsur-

face exploration, consisting of three backhoe trenches with

a combined length of 280 feet, was completed in order to

visually inspect the on-site soils and sediments for evi-

dence of surface fault rupture.

It is our understanding that the proposed project

consists of a one-story, on-grade, corrunercial addition to

312 WESTERN AVENUE • GLENDALE, CALIFORNIA 91201-2836 • (818) 500-9533

I I I I. I I I I I I I I I I I I I I I

9-4-86 12835 Arroyo Street

-~· ·, ~..-.

Page 2 GS86-769

the existing commercial structure located on the site. The

Plot Plan for the development is depicted on Plate 1.

SCOPE

The scope of this investigation included the following:

1. Review of published seismic and geologic literature for

the site and vicinity.

2. Review of aerial photos depicting the site and vicinity.

3. Review of geotechnical reports by various consultants

for nearby properties.

4. Excavation of three exploratory trenches with a corn-

bined length of 280 feet.

5. Detailed logging of the trench at a scale of 1"=5'.

6. Discussion with Mr. James E. Kahle, Associate Geolo-

gist, California Division of Mines and Geology.

7. Analysis of data.

8. Preparation of various logs and figures.

9. Presentation of our procedures, findings and recomrnen-

dations.

LOCATION

The site is located in the San Fernando Industrial

Park, adjacent to and northwest of Arroyo Street, in the

northern San Fernando Valley (see Plate 2). The site is

Califor~a,l ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEE'RING GE~ SYSTEMS

I I I I I I I I I I I I I I I I I I I


Page 3 GS86-769

approximately 900 feet northeast of Foothill Boulevard and

1500 feet southeast of the Pacoima Wash. Adjacent lots to

the northwest and southwest are developed. The adjacent lot

to the northeast is an open field with a parking lot at the

northwest end. The site is situated at an elevation of 1190

feet above sea level.

EXPLORATION

Subsurface exploration was conducted August 7, 1986

using a rubber-tired backhoe. Three, 30+-inch wide trenches

were excavated for investigation of possible faulting.

Trenches A and C were each 105 feet long, and Trench B was

70 feet long. The trenches were excavated to a depth of

about 5 feet. Minor to moderate caving of the trench walls

occurred. The nearest surface ruptures of the San Fernando

Fault trend west-northwest and north (see Plate 2). The

excavated trenches were aligned nearly perpendicular to one

of these two fault trends. The trenches were backfilled

after inspection and logging was completed. Trench backfill

was not compacted to 90% relative compaction.

Trench walls were scraped with a paint scraper in order

to reveal geologic features and materials. A detailed log

of the trenches was prepared and is presented herein (see

Plate 3 in pocket).

Califor~aJ: ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GE~ SYSTEMS

I I I I I I I I I I I I I I I I

',··. ,· .,.· .. ·-.... ,~· ... ·

9-4-86 12835 _Arroyo Street

REGIONAL GEOLOGIC SETTING

Page 4 GS86-769

The site is situated at the northern end of the San

Fernando Valley within the Transverse Ranges geomorphic and

structural province. This province is characterized by

east-west trending mountain ranges that have been thrust

southward over adjacent valleys, such as the San Fernando

Valley. The east-west trend of the Transverse Ranges is

anomolous with respect to the overall northwest structural

trend characteristic of most of California. This anomalous

alignment is due to compressive forces apparently resulting

from the constriction at the bend of the San Andreas Fault,

.. ,:

northwest of the site. The compressive forces are expressed

by development of east-west trending thrust faults and

folds. This results in north-south shortening of the

Transverse Range Province. The 1971 earthquake was generat-

ed by rupture of the San Fernando Fault resulting in uplift

of the San Gabriel Mountains in relation to the San Fernando

Valley. This fault displayed oblique, left-lateral, reverse

displacement.

The northern end of the San Fernando Valley is under-

lain by young alluvial sediments situated over a north

dipping easterly-striking sequence of marine and estuarine

sedimentary rocks of Miocene, Pliocene, and Pleistocene age.

I These sedimentary rocks are folded into a syncline (trough)

I I Californ~a ,f

ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GEO)' SYSTEMS



Page 5 GS86-769

that, at the surface, dips into and is in fault or uncon-

formable contact with the crystalline basement rock complex

of the San Gabriel Mountains located to the north. The

basement rock complex consists of Precambrian metamorphic

and igneous rocks that have been intruded by younger Mesozoic

igneous rocks. The basement complex and overlying sediments

have been deformed by regional faulting and compression.

The San Gabriel Mountains were formed by uplift during

Pleistocene and Holocene time (Ehlig, 1975).

The uplift of the San Gabriel Mountains resulted in

erosion of canyons and the shedding of sediments out into

the San Fernando Valley. These alluvial sediments buried

the older, tilted sedimentary rocks (probably the Miocene

Modelo Formation beneath the site) and formed a generally

southward sloping surface. The site is located on the

geomorphic feature called the San Fernando Surface (U.S.G.S.

Staff, 1971). Historical flooding from the San Gabriel

Mountains along the Pacoima Wash has resulted in deposition

of generally coarse flood plain sediments at the site.

SITE GEOLOGY

The site is underlain by recent stream deposits as

observed in the exploratory trench (see Plate 3) and as

depicted by Barrows, A.G. et al (1974). A thin veneer of

fill (reworked sediments) overlies the stream deposits. The

Califor~a,,I.'. ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GE/ SYSTEMS



Page 6 GS86-769

stream deposits consist of boulder-cobble gravels with

interstratif ied lenses of pebble gravel and coarse sand.

Lenses consisting of silt were observed.

Stratification within the boulder-cobble gravel was

only locally well-developed. No off set or disruption was

observed where the stratification occurred. In areas where

no stratification occurred, features that may represent a

fault rupture were not observed. It should be noted that

the trace of a fault within these deposits where stratifi-

cation does not occur may not be observable/distinguishable.

This was evident where a trench was completed by others in

the Pacoima Wash northeast of the site where a one foot

surface break occurred along the San Fernando Fault. No

trace of the fault was found in the sediments (see Trench 5,

CDMG and Leighton and Associates, 1975).

The sediments observed in the trenches were probably

deposited in historic time and may not be older than 50

years. The 1953 topographic map (see Plate 4) indicates

intermittent flood channels in the vicinity of the site.

Analysis of aerial photos by this off ice for a nearby

project indicated that flooding occurred in the area be-

tween 1928 and 1949 (see California Geo/Systems, Inc.,

GS86-733, August 5, 1986). Analysis of the 1971 aerial

photos indicated that the area had been rough plowed to a

level pad.

Californ~a I' ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GEO/ SYSTEMS


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Page 7 GS86-769

The sediments observed in the trenches are very young

and could not record any faulting prior to their deposition.

Earthquakes large enough to be related to surface fault

rupture occurring in the area have not been reported in

historic time. Geologic mapping of the general area of the

site, by various geologists following the 1971 faulting

event did not reveal surface fault ruptures at the site.

Features that may be interpreted as faults were not observed

in our exploration trench or on the site.

The thickness of the Holocene deposits underlying the

site is not known. The Holocene deposits may exceed 100

feet in thickness. Subsurface exploration to the base of

the Holocene section is not feasible due to the probable

great thickness of the deposits and the loose, boulder

gravel sediments that present excavation and stability

problems. Thus it is not apparently possible to directly

observe the entire Holocene section for evidence of ancient

surface fault rupture.

Site specific geophysical investigations would probably

not be able to detect a fault in the flood plain sediments.

A relatively large offset of the older sedimentary rocks

beneath the alluvium may be detectable if it exists.

However, regional geophysical and groundwater investigations

(Oliver, et al, 1975; Chapman and Chase, 1975) conducted

after the 1971 faulting event apparently do not indicate the

Califor~a./.: ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GE~ SYSTEMS

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Page 8 GS86-769

presence of a Holocene fault, or any fault, that may be

traced under the site.

GROUNDWATER

According to Brown (1975) the site is located within

the San Fernando Hydrologic subarea of the Upper Los Angeles

River Basin. This subarea is separated from the Sylmar

subarea to the north by the San Fernando Fault, which is a

groundwater barrier. Water flows over the barrier in the

subsurface at the Pacoima Notch, northeast of the site.

Flow from the Sylmar Subarea and any rainfall that has

percolated into the ground are probably the principle

contributors to the groundwater table beneath the site.

Plate 5 depicts a cross-section along Foothill Boulevard

prepared by Oliver, et al, 1975. This section indicates

that the groundwater table along Foothill Boulevard was some

100 feet in depth after the 1971 earthquake. The groundwa-

ter table may now have decreased in elevation to pre-1971

earthquake elevations. The groundwater table beneath the

site is probably not much higher than along Foothill Boule-

vard. Perched zones of groundwater may temporarily occur

I beneath the site. However, the highly porous flood plain

deposits would probably allow rapid percolation of water to

I the water table.

I I California;

ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GEOf,..,ve..,...c"'"C"


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9-4-86 _12835 Arroyo Street

FAULTING

Page 9 GS86-769

Major active and potentially active faults within 100

km of the site are depicted on Plate 6. Potential magni-

tudes of earthquakes and selected seismic data is presented

on Plates 7 and 8. The closest major active fault to the

site is the San Fernando Fault. The closest surface rupture

of this fault is located some 50± feet northeast of the site

as mapped by Barrows, et al (1974). The main trace of the

San Fernando Fault is located east and north of the site.

The u.s.G.S. staff (1971) discuss the surface ruptures

closest to the site. In their report they state "One of the

most complex sectors of surf ace rupturing occurs northeast

of the San Fernando Airport in the area of apparent discon-

tinuity between the Sylmar and Tujunga segments of the San

Fernando fault zone. The complexity involves not only

geometric irregularity of the fault strands but also loss of

demonstrable continuity of the fault traces and possible

variation in the sense of the lateral component of displace-

ment."

Kamb, et al (1971) also discusses these surface rup-

tures (see Plate 9) and states " ••. the main line of dis-

placement appears to proceed westward across Arroyo Street

to the roughly westward-trending fault scarp of maximum

height 0.6m (24 in.) that lies southwest of Gladstone

Street. We shall refer to this feature as the Power Line

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Page 10 GS86-769

· .. t·~ . ••. - ' .. ' :·' "

scarp because it crosses a Southern California Edison Co.

transmission line right of way at this point. It displaces

a northwest-trending freeway fence line by 0.9m (36 in.)

left-laterally. From the Power Line scarp, the line of

displacement goes northward to the Pacoima flood-control

channel, following a north-tending break that shows definite

right-lateral displacement where it crosses the freeway

fence line. How the further connection northward to the

Sylmar fault segment is made remains undetermined."

Review of aerial photos, taken three days after the

main rupture event on the San Fernando Fault, does not

indicate the presence of a fault scarp on the site. However,

a lurch crack was evident in the parking lot located north-

east of the site. This crack had a southwest trend that may

have intersected the site. No trace of the lurch crack was

evident on the bulldozed surface of the site in the aerial

photos.

These data and other data that this off ice has reviewed

does not present any conclusive evidence for a continuation

ot a fault zone onto or under the site. This data does

indicate that complex faulting may occur in areas away from

the main traces of the San Fernando Fault. However, without

demonstrable evidence for the presence of a fault beneath

the site, it is not possible to predict the location and

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Page 11 GS86-769

magnitude of any potential faulting that could occur. Site

investigations by this off ice did not find any evidence for

the presence of a fault beneath the site. Thus, this office

concludes, based on data presented in this report, that the

potential for surface fault rupture at the site is low.

SEISMICITY

The site is situated in the seismically active region

of Southern California. The site has been subject to

seismically-induced ground shaking in the past. Severe

ground shaking can be anticipated to occur at the site in

the future. Earthquakes that have probably affected the

site in the past are depicted on Plate 10. The earthquake

events within the 62 mile (lOOkm) radius circle depicted on

the plate are those which have had the greatest affect on

the site. The two closest major historical earthquakes are

the magnitude M8+ 1857 Fort Tejon Earthquake generated by

rupture of the San Andreas Fault and the magnitude M6.4 1971

San Fernando Earthquake.

The epicenter of the 1971 earthquake and representative

aftershocks are depicted on Plate 11. The epicenter of the

main shock was located some 7~ miles north of the site. A

magr.itude M4.5-5.1 earthquake occurred some 2~ miles north

west of the site. During the 1971 earthquake the site may

have experienced peak ground acceleration on the order of

California I' ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GE0ff SVSTF"'1'C:



Page 12 GS86-769

0.4g or greater. The site is located in the region that

experienced ground shaking of Modified Mercalli Intensity

VIII-XI (Cloud and Hudson, 1975). Buildings, utilities and

streets on nearby parcels of land surrounding the site were

damaged (Steinbrugge and others, 1975). A repeat of the

1971 earthquake or a similar event can be expected to

produce strong ground shaking at the site which may damage

buildings and utilities if they are not designed in antic-

ipation of such an event.

A maximum probable earthquake, such as the 1971 earth-

quake, may produce peak ground accelerations at the site on

the order of 0.66g (Greenfelder, 1974). More recent data

presented by Joyner and Fumal (1985) suggest that peak

horizontal ground accelerations at the site may be on the

order of 0.42g. This acceleration data is presented for the

moment magnitude of earthquakes which approximates local

magnitude. Repeatable high ground acceleration on the order

of 0.43g may occur at the site (Ploessel and Slosson, 1974).

Repeatable high ground accelerations is generally responsi-

ble for much of the damage during an earthquake. The

duration of strong ground shaking may be on the order of 19

seconds (Bolt, 1973). These data are believed to be reason-

able estimates of future conditions and is presented for

consideration in design of the proposed commercial addition.

Californ~a ,f ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GEO)' SYSTEMS

I I I I I I I I I I I I I I I I I I


GEOLOGIC AND SEISMIC HAZARDS

Page 13 GS86-769

There are several hazards which should be considered

for design and construction purposes. Each of these hazards

are briefly discussed as follows, as it relates to the site.

Surface Faulting

No faults are presently known to exist beneath the

site. At this time, evidence to substantiate the existence

and location of a possible fault beneath the site is not

known to the authors. While complex surface faulting has

occurred very close to the site, and could conceivably occur

on the site, it is the opinion of this office that the

potential for surface fault rupture at the site within the

lifespan of the proposed buildings is low.

Ground Shaking

Ground shaking is believed to be the most significant

potential hazard to the site. Large magnitude earthquakes

generated along significant faults listed on Plates 7 and 8

can cause strong ground shaking at the site. Reasonable

estimates of the anticipated accelerations and durations of

strong ground shaking for the maximum credible and probable

earthquakes that are likely to affect the site are also

listed on Plates 7 and 8. The anticipated effects of strong

ground shaking should be accommodated in the structural

design of the proposed project.

I Californ~a J' ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GEO/SYSTEMS



Change in Elevation of Ground

Page 14 GS86-769

Surface or subsurface fault rupture can result in

changes of ground elevation (subsidence or uplift). The

general area of the site, as surveyed along Foothill Boule-

vard was uplifted during the 1971 fault rupture event

(Burford and others, 1971). Similar events may result in

additional changes of ground elevations at the site.

Changes in ground elevations may drastically affect surf ace

drainage patterns at the site.

Lurching, Seismic Settlement, Differential Compaction

Lurching, and seismic settlement with associated

differential compaction could occur as a result of seismic

shaking of the unconsolidated surf icial materials at the

site. Lurching is the over-stressing of earth materials by

earthquake-generated waves resulting in deformation, dis-

placement, cracks and fissures in the ground surface at

places other than along faults. As noted previously, lurch

cracks developed in the parking lot adjacent to the site.

The potential for lurching at the site is believed to be

high in the event of a repeat of the 1971 earthquake or

similar event. Seismic settlement may result from

compaction of the loose, unconsolidated materials at the

site. Differential compaction can occur as a result of

lateral and vertical changes of sediment types that respond

Cal ifor~a,/.'. ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GE~ SYSTEMS



Page 15 GS86-769

differentially to seismic vibrations. Proper foundation

design can mitigate most of the adverse affects to buildings

from these hazards. However, paved parking lots and streets

are very susceptible to ground lurching.

Liquefaction

Liquefaction is defined as the transformation of a

granular material (i.e. sand) from a solid state into a

liquefied state as a consequence of increased pore water

pressures (Youd et al, 1973). Based on the apparent low

groundwater table (in excess of 50 feet in depth) and the

presence of boulder-cobble gravels which are not generally

susceptible to liquefaction, it is the opinion of this

off ice that the potential for liquefaction occurring at the

site is low. Thus, the potential hazard of quick condition

failures are not anticipated to occur at the site.

Flooding

The site is situated on the flood plain of the Pacoima

Wash some 1500 feet south of the Pacoima Wash Flood Control

Channel. The Pacoima flood control channel should be able

to divert normal flooding events from the site. However, in

the event of a catastrophic failure of the Pacoima Dam, the

site could be inundated by flood waters.

Californ~·a ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GEO SYSTEMS

. I


9-4-86 Page 16 GS86-769 12835 Arroyo Street

CONCLUSIONS

1. The site is not underlain by a fault that has caused

surface fault rupture during historic time.

2. No evidence is known to the authors to substantiate the

presence of a Holocene fault beneath the site. Thus

the potential for surface fault rupture at the site is

low.

3. The site is underlain by an unknown thickness of

Holocene flood plain sediments that probably overlies

the Miocene Modelo Formation.

4. Strong seismic shaking can be anticipated to occur at

the site within the lifespan of the proposed project.

5. Changes in ground elevation at the site as a result of

nearby fault rupture may occur if a repeat of the 1971

rupture event or similar nearby event occurs.

6. In the event of a nearby large earthquake, the site may

be subject to ground lurching, seismic settlement, and

differential compaction.

7. The groundwater table beneath the site was probably on

the order of 100 feet in depth after the 1971 earth-

quake. The groundwater table may have lowered since

this time.

8. The potential for liquefaction and related hazards

affecting the site is low.

Califor~a,l ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GE~ SYSTEMS


,_


9. The site is located on a flood plain and may be in-

undated by flooding in the event of catastrophic

failure of the Pacoima Dam.

RECOMMENDATION

l. The data presented in this report should be taken into

consideration during the design and construction of the

proposed development.

WARRANTY

The statements and other data presented in this report

either as original information or extracted from research of

references, form the basis for the professional opinions or

judgements given.

This study was conducted according to generally accept-

ed engineering geologic practices for studies of this

magnitude. Additionally, the geologic information presented

is based on interpretations of surface exposures and is

believed to be adequate. However, variations of subsurface

conditions may be expected to a reasonable extent. No other

warranty is expressed or implied.

Cal ifor;a ,l ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GE~ SYSTEMS



Page 18 GS86-769

Should you have any questions as to the content or

significance of any item in this report, please do not

hesitate to call.

CALIFORNIA GEO/SYSTEMS, INC.

Ri~l ~q~ M. Rami z, President CEG 1304 CEG 490

RAL:RMR/rks

Californ~a,l ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GEO,/ SYSTEMS


. ' .: :. ~~ ~ ....


Page 19 GS86-769

AERIAL PHOTOS

2-12-71 Frames 1-38, 1-39, 1-40 American Aerial survey, 1"=200 1

- Observed at the Los Angeles office of California Division of Mines and Geology

CONSULTANTS REPORTS

.~ .. ,,P ' ··-·· .. •· ,,.'j:'t ...

9-17-76 - John D. Merrill; Report of Seismic Investigation; Lots 6 & 7, Tract 22350, Vicinity 12460 Gladstone Ave., Sylmar, CA

1-6-77 - John D. Merrill; Engineering Geologic Supplement, Lots 6 & 7, Vicinity 12460 Gladstone, Sylmar, CA

8-31-78 - John D. Merrill; Report of Seismic Investigation; Lot 8, Tract 22350; Vicinity of 12513 Gladstone Ave., Sylmar, CA

11-12-78 - City of Los Angeles; Letter accepts Merrill report dated 9-17-76

11-20-78 - Foundation Engineering Company, Inc., Report on Compacted Fill; 12847 Arroyo Street, Lake View Terrace, CA

8-5-86 - California Geo/Systems, Inc., Geologic and Seismic Investigation for the Proposed Foothill Shopping Center, Foothill Blvd, City of San Fernando, CA; GS86-733

I Californi1~ / ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GEO/SYSTEMS


. - ' .~;. .


REFERENCES

Page 20 GS86-769·

. ,•.·,···

1. Barrows, A.G., Kale, J.E., and Weber, Jr. F.H.; 1974 Geologic Map of the San Fernando Earthquake Area in CDMG Bulletin 196

2. Bolt, B.A. 1973; Duration of Strong Ground Motion; 5th World Conference on Earthquake Engineering, Rome

3. Brown, G.A. 1975; Groundwater Geology of the San Fernando Valley in CDMG Bulletin 196

4. Burford, R.O., Castle R.o., Church, J., Kinoshita, W.T., Kirby, S.H., Ruthven, R.T., and Savage, J.C.; Preliminary measurements of tectonic movement; in U.S.G.S Professional Paper 733

5. CDMG in cooperation with F. Beach Leighton and Associates, 1975; Trenches Dug Across Surface Breaks of the San Fernando Fault; in CDMG Bulletin 196

6. Chapman, R.H. and Chase, G.W., 1975; Magnetic anomalies and active faults in the San Fernando area; in CDMG Bulletin 196

7. Cloud, W.K. and Hudson, D.E. 1975; Strong-motion data from the San Fernando, California earthquake of February 9, 1971; in CDMG Bulletin 196

8. Ehlig, P.L. 1975; Geologic Framework of the San Gabriel Mountains, in CDMG Bulletin 196

9. Greensfelder, R.W. 1974; Maximum Credible Rock Accelerations from Earthquakes in California; CDMG Map Sheet 23, Scale 1:2,500,000

10. Joyner, W.B. and Fumal, T.E., 1985; Predictive Mapping of Earthquake Ground Motion in Evaluating Earthquake Hazard in the Los Angeles Region-an Earth Science Perspective; USGS Professional Paper 1360

11. Kamb, B., Silver, L.T., Abrams, M.J., Carter, B.A., Jordan, T.H., and Minster, J.B.; Pattern of faulting and nature of fault movement in the San Fernando earthquake; in USGS Professional Paper 733

• California J' ~ ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GEOf'SVSTEMS



REFERENCES - CONTINUED

Page 21 GS86-769

12. King, E.J., Tinsley, J.C., and Preston, R.F.; 1981, Map of Historic Flooding, 1934 to 1956, in the San Fernando Valley, Los angeles County, California; USGS Open File Report 81-153

13. Oliver, H.W., Robbins, S.L., Grannell, R.B., Alewine, R.W., and Biehler, s. 1975; Surface and subsurface Movements Determined by Remeasuring Gravity; in CDMG Bulletin 196

14. Ploessel, M.R., and Slosson, J.E. 1974; Repeatable High Ground Acceleration from Earthquakes - an important design criteria; GSA Abstract with Program, Cordilleran Section, p. 236

15. Schnabel, P.B. and Seed, H.G. (1973); Accelerations in Rock for Earthquakes in the Western United States; Seismological Society of America Bull. V63 #2, p. 501-516

16. Sam Shain, personal communication, 1986; Los Angeles County Flood Control District

17. Steinbrugge, K.V., Schader, E.E., and Moran, D.F. 1975; Building damage in San Fernando Valley; in CDMG Bulletin 916

18. Weber, Jr. F.H. 1975; Surface Effects and Related Geology of the San Fernando Earthquake in the Sylmar Area; in CDMG Bulletin 196

19. Youd, T.L., Nichols, D.R., Helley, E. J. and LaJoie, K.R., 1973; Liquefaction potential of unconsolidated sediments in the Southern San Francisco Bay Region; USGS Open File Report

20. Geotechnical Subconunittee of the State Building Safety Board, (1975), Suggested Guidelines

Californ~a I' ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GEO/SYSTEMS



Page 22 GS86-769

FAULT CLASSIFICATION CRITERIA

Active Faults - 0 to 11,000 years

Active faults show evidence of displacement during the

Holocene epoch (last 11,000 years). Faults are classified

as active on the basis of the following types of evidence:

a) Holocene earth materials have been offset by the fault.

b) Earthquake epicenters are located in close proximity to

the fault.

c) Strong geomorphic expression including scarps, offset

ridges and/or stream valleys, sag ponds, and other

related features.

Potentially Active, Possibly Active

The distinction between "active" and "potentially

active" fault classes is often difficult to determine. A

fault may have strong geomorphic expression, yet not be

overlain by Holocene deposits that are useful in determining

age. Faults in this category may have generated large

earthquakes prior to the wide usage of seismographs. The

large earthquakes were felt but the causative fault was not

identi±ied. These faults may have long recurrance intervals.

Faults are placed in this category soley on the authors

discretion.

Califor:Ja/.: ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GE~ SYSTEMS



Page 23 GS86-769

Potentially Active - 11,000 to 1,600,000 years

Potentially active faults are those which have been

active during the Quaternary epoch (last 1,600,000 years)

and are not classified as Active. Faults are classified as

potentially active based on the following types of evidence.

a) Quaternary earth materials have been off set by the

fault.

b) Groundwater barrier or anomaly occurs along the fault

within Quaternary earth materials.

c) Earthquake epicenters (generally from small earth-

quakes) are located in proximity to the fault.

d) Geomorphic expression of the fault.

Inactive Faults

This category includes faults that have not ruptured

during Quaternary time and for which no dates of movement

are determinable. These faults may be classified "active"

upon further investigation or the occurrence of a large

earthquake such as the 1983 Colinga earthquake.

Faults have been classified by the authors, based in

part upon review of the following references:

Ziony, J.I. and Yerkes, R.F., 1985 Evaluating Earthquake and Surface-Faulting Potential; in Evaluating Earthquake Hazards in the Los Angeles Region - An Earth-Science Perspective, U.S. Geological Survey Professional Paper 1360

Jennings, C.W., compiler, 1975 Fault Map of California with Locations of Volcanoes, Thermal Springs, and Thermal Wells; California Division of Mines and Geology Geologic Data Map #1

Cal ifor';a,1-ENGINEER I NG GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GE~ SYSTEMS

t If

I Ii

r

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I I I I I I I· I I I I I I I

:,-·, -_,·.,.-:: .:-._, .. '


Hart, E.W. 1986 Fault -Rupture Hazard Zones in California: California Division of Mines and Geology Special Publication 42

EXPLANATION OF SEISMIC DATA

"The Maximum Credible Earthquake is the maximum earth-

quake that appears capable of occurring under the presently

known tectonic framework. It is a rational and believable

event that is in accord with all known geologic and seismo-

logic facts. In determining the Maximum Credible Earth

quake, little regard is given to its probability of occur-

rence, except that its likelihood of occurring is great

enough to be of concern. It is conceivable that the Maximum

Credible Earthquake might be approached more frequently in

one geologic environment than in another." (Geotechnical

Subcommittee of the State Building Safety Board, 1975) .

Data considered in determining the Maximum Credible

Earthquake include:

1. The seismic history of the vicinity and the geologic

province.

2. The length of significant faults and individual fault

segments as well as the overall length of related fault

systems within 100 kilometers of the site.

3. The types of faults involved.

4. The prominence of topographic features indicative of

surface movement along faults.

5. The tectonic and structural history.

California If ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GEO.f SVST~MC::


-- , -;; __ ·;;. '· . -~:-


~ :, . ,.

Page 25 GS86-769

6. The tectonic and structural pattern or regional setting

(geologic framework).

The time factor is not considered in the determination.

Distance from the site to the epicenter of the Maximum

Credible Earthquake is taken as the minimum distance from

the site to the causative fault.

It should be understood that there is no precise

analytical method for deriving a Maximum Credible Earth-

quake. Maximum Credible Earthquakes(s), as well as other

seismic data presented, represent the professional opinions

of California Geo/Systems, Inc., and are believed to be

reasonable estimates of potential future conditions.

The Maximum Probable Earthquake (Functional Basis

Earthquake) "is the maximum earthquake that is likely to

occur during a 100-year interval. It is to be regarded as a

probably occurrence, not as an assured event that will occur

at a specific time" (Geotechnical Subcommittee of the State

Building Safety Board, 1975).

Data considered in determining the Maximum Probable

Earthquake include:

1. The regional seismicity, considering the known past

(historic) seismic activity.

2. The faults within a 100 kilometer radius that may be

active within the next 100 years.

3. The types of faults considered.

California If ENGINEERING GEOl.OGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GEOf SVSTEMS



Page 2&:7 GS86-769

4. The seismic recurrence factor for the faults considered

(when known) •

The magnitude of the Maximum Probable Earthquake is

equal or greater than the maximum which has occurred on the

postulated causative fault (or major fault segment for very

long faults such as the San Andreas Fault) within historic

time. Unless there are strong indications from crustal

strain or similar data, that a larger earthquake is likely,

the Maximum Probable Earthquake is generally taken as the

largest earthquake known to have occurred on a given fault

within the past 200 years. Maximum credible and probable

earthquakes are listed to the nearest ~ magnitude, with the

exception of the San Andreas Fault. It is the opinion of

this off ice that the present data set for predicting earth-

quake magnitudes does not warrant more precise values.

The earthquake history in the southern California area

dates from 1769. Thus, slightly over a 200-year base period

is available for deriving the Maximum Probable Earthquake.

It should be noted, however, that accurate instrumental data

for magnitude determinations have only been available in the

area for approximately the past 50 years. Pre-1932 historic

earthquake magnitudes are therefore estimations based on

damage and the extent of the felt area.




Page 27 GS86-769

The Maximum Credible Bedrock Acceleration is defined as

the peak acceleration in bedrock beneath the site which may

be produced by the Maximum Credible Earthquake. Bedrock is

defined as consolidated and/or cemented sedimentary rock,

generally of Pliocene age or older, or metamorphic, or

igneous rock, whichever is closest to the ground surface

beneath the site.

Peak accelerations for alluvial sites will be less than

for bedrock sites. It should be noted that predicted peak

accelerations at a site and intensity of shaking experienced

at a site may not correlate. The intensity of shaking will

vary with specific site conditions such as presence of

Holocene deposits, depth to bedrock, and depth to ground-

water.

The Maximum Probable Bedrock Acceleration is defined as

the peak acceleration in bedrock beneath the site which is

expected to be produced by the Maximum Probable Earthquake.

The postulated Maximum Accelerations presented herein

are based on data developed by Schnabel and Seed (1973) as

presented in Greensfelder (1974). It should be noted that

bedrock acceleration data from instruments located within 20

miles of the epicenters of moderate or stronger earthquakes

'Cal ifor;aJ::. ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GE~ SYSTEMS



are very minimal.

'· , .. ' ·,_::_.-:. __ ,,,_. ·:·, .. -·- ..

Page 2B GS86-769

Although the bedrock acceleration values

are indicated to hundredths (O.XX) of the acceleration of

gravity (g), this is due to the method of picking the data

from graphs and tables. Accuracy of bedrock acceleration

estimates may be no better than tenths (O.X) of the accel-

eration of gravity.

Recent data presented by Joyner and Fumal (1985)

generally suggests lower values for peak ground acceleration

than values presented by Greensfelder (1974) for similar

magnitude earthquakes. Amplification and attenuation of

seismic waves may occur due to local geologic conditions.

At some sites, amplification (including resonance) of

seismic waves may result in higher peak ground accelerations

than presented by Greensfelder (1974). Therefore, this

office continues touse the more conservative data provided

by Greensfelder (197 4) , .until such time as sufficient data

is obtained from accelerographs in close proximity to large

earthquakes.

Repeatable High Acceleration (RHA) refers to the level

of repeated high accelerations in bedrock during an earth-

quake. For sites within 20 miles of an earthquake epicenter

of magnitude 5~ to 7±, the RHA is approximately 65 percent

of the maximum of peak bedrock acceleration; at greater

distances the RHA approached 100 percent of the maximum.

The sustained level of repeated high acceleration is




Page z.g GS86-769

generally more important than the maximum or peak accel-

eration with regard to structural design (Ploessel and

Slosson, 1974).

The term "strong" ground shaking or ground motion as

used herein, refers to accelerations greater than or equal

to 0.05g (gravity) for frequencies greater than or equal to

2Hz. Duration of strong shaking is defined as the elapsed

time between the first and last acceleration excusions

greater than or equal to 0.05 g at a frequency of 2Hz or

greater.

The durations presented in this report, as developed by

Bolt (1973), are based on mathematical calculations and

available data. The durations are based on curves which

represent nearly the upper bound so as to include 90 percent

of available data. These durations are considered realistic

estimates of what could occur during a given earthquake. It

should be noted, however, that longer durations are possible

and could occur.

Califor~a,l ENGINEERING GEOLOGY • SEISMIC STUDIES • SOILS & FOUNDATION ENGINEERING GE/ SYSTEMS

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Tho mod•I utl!td to com~~· th• 1111ff11rc:t 1111n gl'ICIVl.ly of d1t:i.ftg• iR l1!t¥1111l of Wat6r te1bl• betw11ren 1958 and 1971 1hoWP &y dippfod are« O!Dld baff4 on u 195B ~onto\Jr ri.ap pre-pared by dti& Calif1;1rnia Stat. Water kigl'i.ta Board (l962, pl1;1t11:1i 30), ~II dala ft1r l970 ancl 1971 prDVid•d by tho Lot Angel•• County Flood Con.trnl biltrKt (C. C. Gr.-n, writt.l'I communi1:11ticr.n, 1971}1 wat.r 1._1, in waff1 within l km tJ.f A-A' preiJect.d along thi& W(iter tabl111 &urfowi far 1958, 1970, aRd 191~ ...

California

GEO/.: ,/ SYSTEMS, tNc:.

GEOTECH>llCAL CONSULTANTS 312 WE"Si2"=!N AVE.

GLENOALE. CA 91201 '9113) 8d5-8S15 (81EH 84:5·0.490 r91~\ S00-953J

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- - - - - - - - - - - - - - ·- - -·-_.__,._.,-..i;;.;.,,. ______ ............._., ........... ......-....

ACT I VE Ft.UL TS ''

Ft.UtTS LEllUTH DISTAi/CE AUD 0111· ttAXHIUH CREDIBLE HAXIHUH Pll08A8LE ·• ·:. '.

ECTIOll fl\OK SITE EARTHQUAKE EAi\ TltQUAKE ;

HI !es KI lo Hiies Kl I a 0 I rec t 11ag. Acee I Rl!A Dura- Hag , Acee I AHA· Dura•/ (g) (g) t Ion (g} c (g) tlott;·· ..

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~ ...... ~E-- ~7 105 6or+ ' 16 wt E 7'/;e... .7~ .47 31 b 1/e. .~ .4~ l'i .· ~Hr::>WG.<>-.. -~- ·-~·-~ -. ---~- .. ~ ~~,, ---VE.F<.ouG<O ' 1.e.-r zo+ J.I.. 2. (,, <':>V-.! {,,l/e .~ .4~ 1q c. .-;;e, ,34 IZ

~ .... '°'?U;u>..NJ>.... 17 Z5 "'l-0 '-4 1:--N.l 7 .S7 .37 £.(,, '-'le .<;;I . "~ l':t :

~n-tOnD \-liw..'<> 14 zz, ,q "51 -;';>€.. & 'le. -17 . n 14 ' .I~ ,oe 2>' '

~ b.N.~? c,z.o loOO e_4 Zt1 NE:. 8'/e. ·3'3 • ?l-3 30 &'/4 -?>l • e.1 'M '

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\IJ lt•tilER • E1--;;.,...,°"""c_ l'-0 Zl<O 312.. '5l -e.e- 7YZ .of. .of.o £!.,, o:.Y..e -"'· 0$' ~•OS' 10

'

Prti>b Po.""" -'./~""" -01-r Sci.t 47 ({,. '1-l 7 •.07 .67 10 "Yz £·0? ,(...O'f ' <;>·.

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~ GPE.P..•et... eat- 13>2~ "? e, NE'- 7 -2 ·M .et. ~ , .38 ,;!.$ IZ' ,.

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------------ - - - - -·- -FOTEHTIALLY ACTIVE FAULTS

FAULTS l EHG Tit DISTAHCE AND DIR- ttAX !MUM rn ED IOl E MAXI MUM PRDOAilLE ECTIOH FROM SITE EARTHQUAKE EARlHQUAKE

Ml le s Kl lo H 11 es Kl 1 o Direct Hag. Accel RUA Dura· Hag, : Acee\ RHA bura~ (9) (g) t Jon (g) . (g) t Ion

(sec) (sec) .

. Feot .. .,h'~I Acflve .

(F'""17,,,i,, ly a c +.-t~J

' -s-u.uz. !~- .. IAi......:.-~"" M°"''""" 100 Iba 14 ll -S"t>E. 7'/z .3(. .Z3 t:"l (..1/;!!. .z.t1 .1" lb 1-lou .. :-r"-'OOD'· --- ,.., .. ~.-- - -- . ----~· . ... -- -

I .·

NORn\RUX:--oE. 1-hu..? q 17 4 b-"1 "C>W "l/z. .51 -33 lC! (,, . 4 :?:> -1?-'b IZ.

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a .... .,_ i:z,~ (,,Z. 100 I '1 31 NVJ 7•/e . t:.'b .18 ZE>- ''k .11 .11 14 p,,+ .. "' +,o. lly I/ c,f •• ~~

Morr.e.. ~~ - ·l M lf'>•»OW IZ' ix;,e:. - 34 9'1- 47 7Z. W>-l\AJ 7 -07 -07 lZ. "l/e . L-OS L..(15 .Co Al'U'{O'"'(O f'P-1.,..._

KEO f'llo~"-'"'"'' 1-1 ZA 3'0 4"I 7'1 vJ 7 .oG, .o& q " L..()$ L., r::6 I

'S,!.µ PEOP<o A?l-t- 70+ 3a '55 ~ 7'/z -11. .1 (,, Z4 "l/e .of> .o~ q

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-'. Group ol tabli!" !f!OOla. wllli afrow ,nowiRQ ql"Qllnd .t.':, dl~ploetil'l'l!fl1 lind!r 11POOh1. •

0 ••

FlCURE 3.-Stlrface fault~ an(l 11trect o1fsets in the Syhnar fault RP-glnent aud in the area betw~en Lhe Sylmar and Tujunga s~~gn1ents. The Tujunga fault sr.a:rp tern1il1at..ci; h1 t.hc southf:!ast. c::orner of the map. Ila!';e map Uerivcd from aerial

p~o.tography.

R'li"E-K ....... : L=lr-: t-"AuLi1'r-.JC, 'f,. l\.J~wl~.·::.- .::-it- r---1~\..,.~:_,- t'--11,,,.~-.;::_1-_1-;

l 1-.i Ti-!C ~ ~~'-',C...NO"o ~-n.OuAJ<E. "'"' \J.0.c:;;, . .,;..

PP.:.:i!="°""""''a'",><L_ P:.,,"s:_"""' 73 3.

Cafifomy,·· GE:o svs--Ms I j r;;:; • INC.

GEOTECHNICAL CONSULTANTS 31~ WESTE:=tN AVE

'81s1e•5e91s 1s1s1s , Mi;::: c<,r~-.c/?C; - 8(:- ?;.,- 0 PLATE i I GLE.NDALE. CA 91201 ID"--- r ; · IGS "' I 0

..... _. _______ . ---------'-"-·"-'_90 ___ ,s_1.s1_s_o_a_.9~5~3~3--...::... ________ ...;. ______ ;..;;,:..,:. ________________ ..,! ____ ::..,.,;. ______ ;... __ ...J

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Acnve... i=-........_,..... "" ~ ~ .... C,..._,~ .... 11,.,_ R~ ..... ; "'l75.

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Caf.ikir'l"llie

GEo/svsTEMS. INC.

GEO~tili\CM. CONSULTANTS 1~2 WES'iEAt. A\'E.

GLENDA.l.E. c.:. 912(1~ IB"l.B'· SA~! 15 l'!llBl 84~'90 lll,i!'I~ 500-!?.533

t--1""-l.OP< E-."TP1e1>.-s: ~~ "~ ~Oo;I~~ c....._, .... '°""f"o,t~ .... -

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VAN NUYS

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figure 9. Mi;.p Df •pii;•nt.n of main .!.hl).tk 11;1''1d r•pr.;•nttrtiv~ i;ift•rt.hi>t.b $h.Owinv loc:atlon of Pi;ii;oima OQ"' acc•leraaraph..

r--R,-,., ... _...,,1L .. l._...Cl.,J171\A..I v ....... f'i Hvl'/~~10.E.-11977

c=:.-11'=<'.()N:::::-...... M~~•:'...-:'11-..... :.~·.::-:..~.-J-~. \:""~I..'.'"""·~. """t"\-'.~ s~ !="·.:-..:.......-,_; .'., ... :·-·· ~;?.71, CA1-i ,-=~ ... ~'I/::.... r-·/'·'-"-"'"1·' ~.1~\1,:""-· ,-:-,.-- ~"""'""·'-=-"'" 11'.""7"~.~ ~ 1c::\-;1 1'"·' c;:::;:.~_,r.....,~- G. ~'"l , =....,,,._, \C/~

Callfomia /,)"

G20.r~ j' SYSTEMS, !NC.

GEOTECHN!CAL CONSULTANTS 312 WESIE:=!N ,.:i.vE.

GLENaALE. CA g1201 r@:1F.n 845-8815 !S1!:!) B"l!;-6~~0 1e1Rl 500·!?5~3 IDA"TE:'C/70/:;;r IGSc::«. 7C 0 \P' 11-J;:: /,/ /' •. ~1 .... v . tr · ; -M -

2- 9gmw.consrv.ca.gov/shp/apsi_siteinvestigationreports_ocr/... · 1986-09-04 · commissioners...

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