Seismic engineering program report, May-August 1979

CECIL D. ANDRUS, Secretcqy

PREFACE

This Seismic Engineering Program Report is an informal document primarily intended to keep the ever-growing community of strong-motion data users apprised of the availability of data recovered by the Seismic Engineering Branch of the U.S. Geological Survey. strong-motion instrumentation is supported by the National Science Foundation (Grant CA-114) in cooperation with numerous Federal, State, and local agencies and organizations.

This issue contains a summary of the accelerograms recovered from the u.s. Geological Survey's (USGS) National Strong-Motion Network during the period May 1 through August 31, 1979. A report on the Gilroy (Coyote Lake) earthquake of August 6, 1979, is presented along with summaries of recent reports, notes on strong-motion information sources and the availability of digitized data, and additional information pertinent to the USGS and other strong-motion programs. The data summary presented in table 1 includes those accelerograms recovered (although not necessarily recorded) during the period May through August, 1979; this procedure will be continued in future issues so that the dissemination of strong-motion information may be as expeditious and current as prac~icable.

The Seismic Engineering Program of

Ronald L. Porcella, Editor U.S. Geological Survey, MS 78 Menlo Park, California 94025

Preface - - - - - - - - - - - - -

Strong-motion records from the- Gilroy, Califocnia earthquake of August 6, 197~ - - - - -

Summaries of recent r~po£ts -

Strong-motion informatioa, data reports, and avai1ability of digitized

Errata - - - - - - - - -

Table 1 - Swaaary of acceleroqraas, May- August, 1979 - - - - - - - - - - 12

Figure 1 - Hawaii strong-motion network - - - - - - 2 - Accelerograms from the Island of Hawaii

3 - Lr'~ation map of close-in stations, Gilroy earthquake of

4 - Location map of regional stations, Gilroy earthquake of

5 - Gilroy array accelerograms, earthquake of August 6, 1979

6 - Plot of peak-acceleration attenuation, Gilroy earthquake of August 6, 1979 - - - - - - - - - - - - - - - - -

August 6, 1979 - - - - - - - -

August 6, 1979 - - - - - - - - - - - - - - - - - - -

(COYOTE LAKE), CALIFORNIA EARTHQUAKE OF AUGUST 6, 1979

A magnitude 5.7 (ML) earthquake occurr~d at 10:05:23 local time on August 6, 1979 in ttie central California coastal region at a depth Qf about 6 km; 37.100N and 121.500W in the Calaveras fault zone near Coyote Lake, approximately 10 km north-northeast of Gilroy (fig. 3). This event was the largest to occur in the region since~a magnitude 6.6 earthquake near the town Coyote on July 1, 1911, and was reported fe t from Santa Rosa south to the San Fernan o Valley and -east to Reno, Nevada.

Figure 1. - u.s. Geological Survey strong-motion network im Hawaii.

FROM THE GILROY

the epicenter was located at

Some dama e was reported in the Gilroy-Hollister area and included cracked plaster and stucco, broken windows, and fallen stock from store shelves.

The triggered all accelerographs within a radius of approximately 40 km of the epicenter; the most distant approximately 114 km from the epicenter. locations of ground-motion instruments relative to the epicenter are shown in figure 4. dots in this figure indicate instruments from which a record was obtained, and the circles indicate instruments that were operational at the time of the earthquake but did not trigger; stations that are not known to have been operational at the time of the earthquake are omitted from the figure.

Figure 3 shows the locations of close-in stations and their relation to the epicenter and fault zone. Two arrays of ground stations, the Gilroy and Bear Valley -arrays, recorded the event. All stations in the Gilroy array are within 16 km of the epicenter and extend from a rock site across an alluvial valley to a rock site. characteristics provide data that are important in studies propagation, effects. Gilroy

Therefore, of near-field Refraction (Coyote

surveys Lake)

mechanism, motions, and down-hole earthquake

Hilo, Fish and Wildlife Refuge

a-----SCM-------1

Volcano Observatory

these records with the earthquake of March 6, 1979 is questionable. Top and bottom data traces on accelerogram show horizontal motion, middle ~race shows vertical motion.

Figure 3. - Location of strong-motion arrays and close-in stations that recorded the Gilroy, California earthquak.e of August 6, 1979 (from Porcell,a and others, 1979).

SUMMARIES OF RECENT REPORTS*

ENGINEERING FEATURES OF THE SANTA BARBARA EARTHQUAKE OF AUGUST 13, 197.8

u.s.

FOUR DEFINITIONS OF STRONG-MOTION DURATION: THEIR PREDICTABILITY AND UTILITY FOR SEISMIC HAZARD ANALYSIS ....... j___---;;,;:';,.,:;;;-,.:-,

Figure 4 . - Location of strong-motion stations in the region of the August 6, 1979 Gilroy, California earthquake (from Porcella and others, 1979).

UP

t~

__u_P~~~--------------------------------------

PRELIMINARY SUMMARY OF THE U.S. GEOLOGIC SURVEY STRONG-MOTION RECORDS FR.OM THE OCTOBER. 15, 1979 IMPERIAL VALLEY EARTHQUAKE

STRONG-MOTION INFORMATION, DATA REPORTS, AND AVAILABILITY OF DIGITIZED DATA

U.S. Strong-Motion Network Data

Figure 6. - Plot of attenuation for peak acceleration with increasing' epicentral distance (from Porcella and others, 1979).

REPRESENTATION OF EARTHQUAKE GROUND MOTION: SCALED ACCELOROGRAMS AND EQUIVALENT RESPONSE SPECTRA

u.s.

EDISINOAA WORLDWIDE STRONG-MOTION DATA

13 .s. Dept. of Commerce

CIT~ EERL S-M earthquake accelerograms, digitized & plotted data; vol II, III, IV~ Part B; Record 1037 (1966 Parkfield earthquake)

vol I, II; Part C Record 1041 (1971 San Fernando earthquake; caaponent direction-Paooiaa Dam accelerogram)

USGS S-11 Station No. 1250 Gilroy, Gavilan College (Component direction - all s-11 records since Oct. 1972)

USGS S-11 Station 2420 War lladrid, Missouri ~nt directionevents of 6-13-75 and 3-24-76)

USGS 8-11 Station no. 181~

J.st floor (Coaponent direction pricx to 7-15-70)

floor and roof) ~t directions are:

USGS S-11 Station llo. 122; Gleodale, California (Calponent direction - events of 4/8/68 and 2/9/71)

USGS S-M Station llo. 125(828); Lake Hughes Array Station 1 (lA) Calponent direction:

ER.llATA

Temblor, Calif. No. 2 USGS Station No. 1097 35 45'07" N 120 15'52 w

T - N69W Temblor, Calif. USGS Station No. 1438 35 42'36 N 120 10'12 w

T - S69E Table 1. - Summary of acceZerograms recovered during May - August 1979

16 May 1978- 12 June 1979 Cent. Alaska Epicenters and magnitudes unknown

20 January 1979- 29 July 1979 s. Hawaii Epicenters and magnitudes unknown

See footnotes at end of table. Station ncyne (owner}

Talkeetna, Alaska FAA/VOR (USGS}

Fairbanks, Alaska Duckering Hall (USGsr

Fairbanks, Alaska College ObServatory (USGS)

Note: One each.additional·records recovered at Talkeetna and at College ~bservatory; maximum acceleration less than 0.05 ~·

Waimea, Hawaii Waimea School (USGS}

Honokaa, Hawaii Fire Station (USGS)

Hilo, Hawaii Univ. of Hawaii (USGS}

Hilo, Hawaii Fish & Wildlife (USGS}

Hilo, Hawaii Sewage Plant (USGS) Station coord.

62.30 N 150.10 w

64.85 N 147.82 w

64.86 N 147.83 w

20.03 N 155.67 w

19.734N 155.050W s-t Direction

2000 0.05 Up noo

1560 Up 0660 Duration

1-peak Table 1. - Summary of acceZerograms recovered during May - August 19?9 - Continued

16 November 1978- 6 August 1979 Cental Calif. Epicenters and magnitudes unknown

13 February 1979 1921 UTC Central Calif.

36. 56N, 121.16W

5 March 1979 0818 UTC Central Calif. Epicenter and magnitude unknown

10 March 1979 0831 UTC Central Calif. Epicenter and magnitude unknown

See footnotes at end of table. Station name (owner)1

Hawaii Nat'l Park Volcano Observatory (USGS)

Wahaula, Hawaii Visitor Center (USGS)

Note: The largest amplitude record for each station is questionably associated with the magnitude 4.7 event of March 6, 1979; this earthquake was located at 19.520N and 155.270W at a depth of 28 km.

Bear Valley Array Sta. 11, Wilkinson Ranch (USGS)

Bear Valley Array Sta. 10, Webb Ranch (USGS)

Bear Valley Array Sta. 14, Butts Ranch (USGS)

Bear Valley Array Sta. 12, Williams Ranch (USGS)

Bear Valley Array Sta. 10, Webb Ranch (USGS) Station coord.

19.42 N 155.29 w

19.33 N 155.03 w

36.61 N 121.11 w

36.53 N 121.14 w

36.57 N 121.04 w

36.66 N 121.25 w

36.53 N 121.14 w s-t2 Direction3 Max accl4 (s)

• 3600 0.06 Up 2700

** Table 1. - Summary of aaaelePogPams reaov~red during May - August 1979 - Continued

15 March 1979 2006 UTC Central Calif.

36. 61N, 121. 09W

16 March 1979 2000 UTC Central Calif. Epicenter and magnitude unknown

21 March 1979 17 July 1979

Epicenter and magnitude unknown

21 March 1979- 6 August 1979 N. California Epicenter and magnitude unknown

See footnotes at end of table. Station name (owner)1

Bear Valley Array Sta. 14, Butts Ranch (USGS)

Bear Valley Array Sta. 9, Schrolls Ranch (USGS)

San Francisco 3333 25th St. (USGS)

Basement Roof (9th)

San Francisco 3250 Van Ness Ave. (USGS)

San Francisco BART Tube (USGS)

Section 16 Section 19

San Francisco BART Vent Shaft (USGS)

Level -48 Level + 9

San Francisco 555 Pine Street (USGS)

Basement .Bth floor & rae '16th floor & ra k Roof (18th) ft ft

· Station coord.

36.57 N 121.04 w

36.63 N 121.28 w

37.75 N 122.42 w

37.81 N 122.42 w

37.80 N 122.38 w

37.80 N 122.39 w

37.79 N 122.40 w s-t2 Direction3 Max accl4 DurationS

3100 0.11 Up 2200 0.1 .04 .10 1-peak

15 March 1979 2006 U'l'C Central Calif. 36.61N, 121.09W Magnitude 3. 0

Central Calif. 36.5311, 121.13W Magnitude 3. 3

27 May 1979 1628 UTC Central Calif.

Central Calif. Epicenter and magnitude unknown

29 llay 1979 2216 1ftC Central Calif. Epicenter and magnitude UDkDOIID

26 June 1979- 5 Septeaber 1979 H. California Epicenter and aagnitude unknown

See footnotes at end of table. Station name (owner)_l

Bear Valley Array Sta. 14, Butts Ranch (USGS}

Bear Valley Array Sta. 6, James Ranch (USGS)

Bear Valley Array Sta. 10, Webb Ranch (USGS)

Bear Valley Array Sta. 6, Jaaes Ranch

Bear Valley Array Sta.. 6, James Ranch (USGS) Station coord.

36.57 N 121.04 w

36.51 N 121.10 w

36.53 N 121.14 w

36.51 H 121.10 w

36.51 N 121.10 w

36.51 N 121.10 w

38.34 H 121.11 w s-t2 Direction$ Max accl4 DurationS (s)

1.1 3100 0.11 Up 2200

3100 Up 2200 .04 .10

(s)

1-peak Table 1. - SUmmary of acceZ~grams recovered dur~~g May -August 1979 - Continued

5 June 1979- 4 August 1979 South Carolina Epicenters and magnitudes unknown

13 June 1979 0709 UTC Imperial Valley, 33.08N, 115.62W Magnitude 3.7

13 June 1979 1946 UTC Imperial Valley, 33.02N, 115.67W Magnitude 4.2

13 June 1979 2021 UTC Imperial Valley, 33.12N, 115.62W Magnitude 3.3

29 June 1979 0553 UTC Big Bear Lake, Ca. 34.25N, 116.90W Magnitude 4.6

30 June 1979 0034 UTC Big Bear Lake, Ca. 34.24N, 116.90W Magnitude 4.8

See footnotes at end of table.

Jenkinsville, s.c.

Monticello Dam (USGS)

Calipatria, Calif.

Fire Station Ca.

(USGS)

Brawley, Calif.

Municipal Airport Ca.

(USGS)

Calipatria, Calif.

Fire Station (USGS)

Calpatria, Calif.

Fire Station (USGS) Ca.

Cherry Valley Johnson Residence (USGS)

Forest Falls Mill Creek Canyon (USGS)

Whitewater Trout Farm, Whitewater Canyon, (USGS)

North Palm Springs Post Office, (USGS)t Shared abutment (Center crest)

Note: Three additional records recovered at this station; maximum acceleration less than 0.05 ~ Station coo rd.

34.30 N 81.33 w

33.13 N 115.52 w

33.13 N 115.52 w

33.13 N 115.52 w

33.98 N 116.99 w

34.09 N 116.92 w

33.99 N 116.66 w

33.92 N 116.54 w Direction3 Max accl4 DurationS

6.1 1800 0.05 Up 0900

3000 Up 2100 .04 .05

.08 .07 1-peak .12

30 June 1979 0034 UTC -continued

30 June 1979 0703 UTC Big Bear Lake, Ca. 34.25N, 116.90W Magnitude 4.5

9 July 1979 2120 UTC Central Calif. 36.55N, 121.18W Magnitude 3.0

17 July 1979- 6 August 1979 N. California Epicenter and magnitude unknown

See footnotes at end of table. Station name (owner )_1

Cedar Springs Dam Toe Station, (CDWR)t

Cedar Springs Dam Crest Station, (CDWR)t 117.31 W

Perris Dam Crest Station, (CDWR)t 117 .18 W

Cedar Springs Dam Toe Station, (CDWR)t

Cedar Springs Dam Crest Station, (CDWR)t 117.31 W

Bear Valley Array Sta. 1, Fire Station (USGS)

Bear Valley Array Sta. 4, Bickmore Cyn. (USGS)

Bear Valley Array Sta. 5, Callens Ranch (USGS)

Bear Valley Array Sta. 10, Webb Residence, (USGS)

San Francisco 3333 25th st. (USGS)

Basement Roof (9th) Station coo rd.

34.30 N 117.31 w

34.30 N 117.31 w

36.57 N 121.18 w

36.57 N 121.22 w

36.67 N 121.20 w

36.53 N 121.14 w

37.75 N 122.42 w Direction s-t

0200 0.06 Up 2900

3100 Up 2200 Duration

.os

.42 Table 1. - Summary of acaelerogmms recovered ~"'ng May ..... August 1979 - Continued

6 August 1979 1705 1ftC -continued

See footnotes at end of table. Station name (owner)J

Gilroy Array Sta. 1 Gavi1an College (USGS)

Corralitos Eureka Canyon Rd. (CDMG)

San Juan Bautista 101/156 Overpass

San Juan Bautista 24 Pol.k St.

Hal.ls Val.l.ey Grant Ranch

SAOO Central.

Capitola 405 Capitol.a Ave.

San Jose Great Western Bl.dg.

San Jose Town Park Towers Station coord.

37.05 N 121.80 w

36.86 N 121.58 w

36.86 N 121.54 w

37.34 N 121.71. w

36.78 H 1.21.45 w

36.97 N 1.21.95 If

37.34 N 121.89 w

37.34 N 121.89 w s-t2 Direction3' Max accl4 Duration5 (s)

3200 0.13 Up 2300

2400 Up 1500 .08 .10

(s)

2.0 0.4 Table 1. - Summa~y of acceZerograms recovered during May - August 1979 - Continued

** Table 1. - Summary of acceZerograms recovered during May - August 1979 - Continued

6 August 1979 1705 UTC -continued

see footnotes at end of table. Station nre (owner)

Palo Alto VA Hospital Bldg. 5 (USGS)

Palo Alto .1900 Embarcadero Rd. (CDMG)

Monterey City Ball Few Ball (USGS}

Dos Amigos Pumping Plant (CDWR)

Bear Valley Sta.

• 36.57 N

Bickmore Canyon (USGS)

Sear Valley Sta. 11 Wilkinson Ranch (USGS)

sear Valley Sta. l. Fire Station (USGS)

Bear Valley Sta. 10 Webb Residence (USGS)

8ecu: Valley Sta. 14 Upper Butts Ranch Station

121.04 w s-t coord. (s)

36.57 N Direction3 Max accl4 Duration5

1800 0.03 Up 0900

.05 .02 .08 Table 1. - Summary of aaaelerograms reaov~red during May - August 1979 - Continued

South San Francis~ **

6 August 1979 1705 UTC -continued

See footnotes at end of table. Station name (owner):L

Oakland Title Ins. & Trust

San Francisco Diamond Heights (CDMG)

San Francisco 3333 25th St. (USGS)

San Francisco 555 California St. (USGS)

San Francisco 600 Montgomery St. (USGS)

San Francisco 3250 Van Ness Ave. (USGS)

El Cerrito Capwell's Dept. Store 122.30 w (CDMG)

San Francisco VA Hospital (USGS)

Richmond Field Station (UCB)

Note: This data summary for the Gilroy earthquake includes ground stations only; for structural response data, see Porcella and others, 1979. s-t2 Direction3 Max accl4 DurationS Station (s) coord.

37.81 N 122.27 w

37.74 N 122.43 w

37.75 N 122.42 w

37.79 ·N 122.40 w

37.80 N 122.40 w

37.81 N 122.42 w

37.78 N 122.50 w

37.92 N 122.33 w **

• (s)

** Table 1. - Summary of acceZerograms recovered during May - August 1979 - Continued

6 August 1979 2233 UTC Gilroy, Calif.

37. OON, 121. 48W

6 August 1979 2236 UTC Gilroy, Calif.

36. 96N, 121. SSW

1 CDMG - California Division of Mines and Geology CDWR - California Department of Water Resources UCB - University of California, Berkeley USGS - u.s. Geological Survey t WWVB time code is incomplete qr nonexistent; correlation of accelerogram with event is questionable.

2 S-wave minus trigger time.

• S-t time is questionable or cannot ~e determined.

Azimuthal direction of case acceleratiJn for upward trace deflection on accelerogram (opposite direction to p~ndulum motion).

Unless otherwise noted, maximum acceleration recorded at ground or basement level.

** Denotes maximum acceleration is less than O.OS ~ at ground stations or less than 0.10 ~ at upper floors of buildings

Time duration between first and last p~aks of acceleration greater than 0.1 ~· Station name (owner)l

Gilroy Array Sta. San Ysidro F .F. (USGS)

Gilroy Array Sta. San Ysidro F.F. (USGS)

Note: Unidenti~iable aftershock records were obtained at Gilroy array st6tions 2 and 6; peak accelerations were O.OS ~ and 0.06 ~' ~espectively. Additional records that could not be identifibd were obtained at Gilroy array stations 2 (3 each) 3, and 4/; peak accelerations were less than O.OS ~· Station coord.

37.026 N 1.3 121.484 w s-t2 Direction3 Max accl4 Duration5

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