Seismic engineering program report, September-December 1980

KAHOOI..AWE

JAMES G. WATT, Secretory

Geological Survey Dallas L. Peck, Director

Free on application to Branch of Distribution, U.S. Geologico/ Survey 604 South Pickett Street, Alexandria, VA 22304 This Seismic Engineering Program Report is an informal periodical primarily intended to keep the ever-growing i nternat ion a 1 comrnun i ty of s trong-rnot i un data users apprised of the nature and ava i 1abi 1 i ty of data recovereo by the Seismic Engineering Branch of the U.S. Geological Survey (USGS). This Strong-Motion Program is administered by the USGS ana supportea by tne National Science Foundation (Grant CA-114) in cooperation witn nurne:ruus Federal, State, and local agencies ana organizations. Major objectives of the program include recording both strong ground motion ana the response of various types of engineered structures auring ROtentially darnaginy earthquakes ana disseminating ti1is strong-motion inforn1ation ana data to tne eartn4uake engineering research and aesign corrunur1ity.

This issue contains a summary of the accelerograms re:covereu frOiiJ the USGS Nation a -1 Strang-Motion Network dur i ny tne period Septernuer 1 tt1rough Decemoer 31, 1980. A report on the Hawaii Strong-f'I'Jotion Network ana a revishHJ of USG~ strong-motion data recoraed auring the maynitude 5.9, 1979 Gilroy ~Coyote Lake) earthquake and the magnituae 5.U, 1979 lrniJerial Valley aftt:rst1ock are included along with summaries of recent strong-motion re!Jorts, notes on tt1e availability of digitizea data, and additional 9eneral information pertinent to the USGS and to other strong-motion programs. The data summary includea in table l contains information on those accelerograms recoveree lctltlwuyn not necessarily recorded) during the perioa Septemoer December 1980; this procedure has been adopted so that the d i ssemi nation of s trung-111Ut i 011 information may be as expeditious and current as practicable.

RECENT STRONG-MOTION RECORDS

Fifty-four accelerograph records were recovered from the Strong-Motion Network during the period September l through December 31, 1980; these accelerograms are related to at least 24 earthquakes that occurred in California,. Alaska, Hawaii, and South Carolina (see table l, 13nd of report). Event information listed in table l and given in the following paragraphs was taken from Preliminary Determination of Epicenters, published monthly by the U.S. Geological Survey.

The Bear Valley array southeast of Hollister, California, earthquakes that occurred between May 5 and November 22, 1980; four of these records contain peak accelerations greater than 0.05 9.· acceleration was a 0.31 9. peak horizontal motion recorded at Bear Valley array station 11 during a magnitude 4.1 (IVlL) event on October 13, 1980; epicentral distance was about 2 km.

A magnitude 4.4 earthquake on October 31 in the Imperial Valley, California, triggered accelerographs at El Centro array stations 11, 12, and 13, Calexico Fire Station, and the El Centro differential array station. The event caused slight damage in Calexico and produced acceleration of 0.12 gat El Centro array station 12.

Three strong-motion recorders on the Big Island of Hawaii during the period October 1979 through September 1980; a maximum horizontal acceleration of 0.07 g was recorded at the Honokaa Fire Station on the northeast part of the island.

A magnitude 7.0 (fviL) earthquake off the coast of northern California on November 8 injured six people, caused damage in many communities along the coast of Humboldt county, and was felt from southern Oregon to the San Francisco bay area. This event triggered just one USGS accelerograph at I:Jutler Valley station 2 and produced a maximum horizontal ground acceleration of 0.10 9.· On earthquake caused slight damage in Georgetown in northeast California and was felt widely in the area from Sacramento accelerographs at Boca and Martis Creek Darns were triggered but recorded maximum accelerations less than 0.05 9.· Additional earthquakes that produced maximum accelerations less than 0.05 9. were recorded at USGS stations near Jenkinsville, South Carolina; southwest of Bakersfield, Calif.; in the Sierra Nevada foothills east of Tulare, Calif.; near the central California town of Hollister; and in the Talkeetna-Cantwell region in south-central Alaska (see table I). By R. L. Porcella and J. C. Switzer

U.S.

Tahoe.

5.2 (ML)

REVISED STRONG-MOTION DATA, PART II

The National Strong-Motion Network operated by the U.S. Geological Survey since 1973 is supported by the National Science Foundation (Grant CA 114). The objectives of the program are to record strong ground motions and the response of representative types of engineered structures during potentially damaging earthquakes and to disseminate processed data and information about the records, sites, and structures to external users in earthquake engineering research and design practice. The dissemination of this inforrnation and data is achieved in various ways, including the triannual publication of this Seismic Engineering Program Report (SEPF~).

The SEPR has been published on a regular basis since 197 4 and includes peak accelerations greater than 0.05 g recorded at ground level and greater than 0.10 9. recorded at upper le_vels of st~uctu_res. Ti1is minimum acceleration level Is based pr1rnan ly on the apparent significance of this data for use in engineering studies and on the current capability of the USGS to process strong-rnotion records and rnay vary with both the significance and degree of seismic activity and number of personnel available at any given time.

Because of the recent increase in "real time" strong-motion data at both far- and near-source distances, it has become apparent that more detailed lists of the recorded ground accelerations and source site distances for recent selected earthquakes woulo be useful ground-motion attenuation studies (Porcella, 19U2). Although peak acceleration is not directly related to frequency content or duration of strung mution, the value can be readily obtained from an accelerograrn and has been used widely in recent years in studies of the attenuation characteristics of horizontal ground acceleration source-site recording-site conditions.

USGS data from the magnitude 5.9 Coyote Lake (Gilroy, California) earthquake of August 6, 1979, and the magnitude 5.0 Imperial Valley aftershock of October 15, 1979 (23:19:29 UTC), have been rescaled to 0.001 g and together with epicentral distances are listed in tables 2 and 3. References: Lee, W. H. K., Herd, D. G., Cagnetti, V., Bakun, W. H., and Rapport, A., 1979, A preliminary study of the Coyote Lake earthquake of August 6, 1979 and its major Open-File Report 79-1621, 43 p. Porcella, R. L., 1982, f-{evised strong-motion data, in Se isrTtic Engineering Program f-{eport, iViay-AurJUSt 1980: U.S. Geological Survey Circular 854-B, 25 p.

By R. L. Porcella

aftershocks:

varying earthquake magnitudes, source mechanisms, and

U.S. Geological Survey _

SUMMARIES OF RECENT STRONG-MOTION REPORTS -1<

PROCESSED ACCELEROGRAMS FROM MONTICELLO DAM,JENKINSVILLE,SOUTH CAROLINA, 27 AUGUST 1978,AND TWO LATER SHOCKS

Gilroy array sta. 1 1408

Distance from epicenter at 37.ll N. lat, 121.53°W. long (+ 1 km; Lee anu others, 1979). When coordinates of station and (or) source are listea to 0.01 or 0.001 degree, implicaton is an accuracy in epicentral distance of approximately 1.0 or 0.1 km, respectively; a proyram of upgrading all station coordinates to 0.001 degree is underway.

Azimuthal direction (degrees clockwise from north) of case acceleration for upward trace deflection on accelerogram; vertical component listed as "up" or "down."

Time between first and last peaks of acceleration greater than 0.10 ~· Coyote Lake (Gilroy) earthquake

distancel (km)

8.9 Ground acceleration Peak

o. 129 Up

Holtville Post Office 5055

Distance from epicenter at 32.767°N. lat, 115.44l W. long (+ 0.6 Km; D. Boore, written commun., March 1980). When coordinates of station ana (or) source are listed to 0.01 or 0.001 aegree, the implication is an accuracy in e~icentrdl distance of approximately 1.0 or 0. l km, respectively; a pro~ram of upgraaing alI station coordinates to 0.001 degree is underway.

Azimuthal direction (degrees clockwise from north) of case acceleration for upward trace deflection on accelerogram; vertical component listea as Up or down.

1-story bldg.; 5m by 7m concrete slab, wood frame

l-story oldg.; concrete block, slab floor

6-6-77; (in p1ace)

b-9-77;

2-18-73; Local geology

shallow ash over lava flows (rock)

shallow ash over 1ava flows (rocK)

lava flows (rock)

lava flows (rock)

lava flows

lava flows (rock)

lava flows (rock)

vo-lcanic asn deposits

volcanic ash deposits

volcanic asn deposits

volcanic ash aeposits

deep (200m) sediments over basalt Number events recoraea3 peak accel.

none Recordings 20.05 ~;

4; 0.17' 0.06, 0.06, ana 0.05 ~

1; o. n ~

2; 0.07 ana 0.1 I .9.

and 0.22 ~

l; 0.06 £.

2; 0. l I

ana 0.44 ~

l; 0. 11 .9..

2; O.Ob ana O.U7 .9..

none Table 4.- USGS accelerograph stations in the Hawaiian Islands - continuea

8-2-79; (in p1ace) Local geo l ogy2

deep sedi111ents

deep sediments over basalt

vo l can h: ash

lava flm-1s Nunn.Jer Recordings events recordea3 peak accel.4

none

none

none

none

none

none

none

none

none none

none Table 4.- USGS accelerograph stations in the Hawaiian Islanas - continuea

Strong-motion stations, events, and recordings listed are complete through December 1980.

Positive correlation of most records with a specific earthquake cannot be made because the Hawaii network accelerographs do not have real-time capability; peak acceleration listea is maximum for each event and was recorded on one of two horizontal or one vertical instrument components. Structure size; type

9-1-78; (in p1ace) Local geology2

oeach sand Number events recoraed3 peak accel.4

none Recordings

2; 0.05 and 0.08 ~

none

l; 0.17 .9.

none

EXPLANATION

• Accelerogroph Seismoscope

Molokai fracture zone 20'

Figure 1.- Hawaii strong-motion network

important graphical results.

Only one event is identified: 27 August 1978; 1023 UTC; coordinates 34.31 N, 81 • .33 W; depth 1.5 km; magnitude 2. 7. The second and third events occurred during the period from 31 August 1978 to 6 November 1978. On this section of the original film record a total of eight events were recorded. The two selected for this processing package had peak horizontal accelerations, scaled frorn the records, of 0.22 and 0.24 g. The identified event had a peak of 0.25 g_, the largest earthquake in central or eastern North America.

Digitization of the three recordings was carried out by IOM- TOWILL of Santa Clara, California; USGS processing of the data has resulted in plots of the corrected acceleration, velocity, and displacement and response spectra. The results of corrected data only are available on magnetic tape. Reference: U.S. Geological Survey Open-File Report 81-0448, 35 p.

This report serves first to document a magnetic tape containing the results of processing of the strong-motion data from this accelerogram, and second to reproduce the more important graphical results. This processing follows, by a 1it tie more than one year, processing of three records that were described in our l'v1arch 1981 Open-File Report 81-0448 to which reference may be made for a description of the site, records, and processing.

Digitization was carried out by IOM- TOWILL of Santa Clara, California, and USGS processing has produced plots of acceleration at three stages of correction: corrected velocity and displacement, and response and Fourier spectra. available on magnetic tape from the Environmental Data and Information Service (see "Data Sources," this report).

The special processing required for the evidently visible 25 and 35 Hz content has resulted in the following plots. "r-{aw data" signifies the input to the correction scheme and corresponds to uncorrected data of Caltech and USGS processing. These data are interpolated at 500 pointsfsecond, and the plot is labelled "interpolated/decimated." 8utterworth filters whose corner frequencies are 3 db down are used to band pass the interpolated data between the low frequency limit of 1 Hz (with n =1, first order) and the high frequency lirni t of 50 Hz (n = 2, second order). These plots are labelled "filtered/windowed." The second page of plots for each cornponent contains the acceleration, ve1oci ty, and displacement with the instrurnent correction applied. All plots are scaled so that the peak value, listed in the title, fills the vertical axis.

The response spectra plots, both 1inear and tripartite, contain plots from I to 25 Hz, or 0.04 to I second. known recorded acceleration from an

16 OCTOBER 1979,0706 UTC

By P. N. IViork and A. G. 8rady

The high frequencies, up to 50 Hz, are portrayed in the Fourier spectra plots.

Reference: U.S. Geological Survey Open-File

can be seen by comparing two strong-motion records of the Coyote Lake, California, earthquake of 6 August 1979 (lvrL = 5.9). One record at a site on Franciscan bedrock had a peak horizontal acceleration of 0.13 g and a peak horizontal velocity of 10 cmjsec. The other, at a site 2 krn distant Of! 180 meters of Quaternary alluv iurn overlying Franciscan, had values of 0.26 g and 32 cmjsec, amplifications by factors of 2 and 3. -Horizontal motions cornl-luted at the alluvial site for a linear plane-layered model based on measured P- and S-wave velocities show reasonably good agreement in shape with the observed motions, but the observed peak amplitudes are greater by a factor of about 1.25 in acceleration and 1.8 in velocity. About 15 percent of the discrepancy in acceleration and 20 percent in velocity can be attributed to the difference in source distance; the remainder may represent focusing by refraction at a bedrock surface concave upward. There is no clear evidence of nonlinear soil response. Fourier spectral ratios between motions observed on bedrock and alluvium show good agreement with ratios predicted from the 1inear model. In particular, the observed frequency amplification spectrum agrees with the computed value, indicating that no significant nonlinearity occurs in the secant shear modulus. Computations show that nonlinear models are compatible with the data if values of the coefficient of dynamic shear strength in terms of vertical effective stress are in the range of 0.5 to 1.0 or greater. The data illustrate that site amplification may be less a matter of resonance involving reinforcing multiple reflections, and more the simple effect of the low near-surface velocity. theory leads to amplification approximately proportional to the reciprocal of the square root of the product of density and shear-wave velocity.

Reference: Bulletin of the Seismological Society Report 81-1214, 20 p.

THE EFFECT OF QUARTERNARY ALLUVIUM ON STRONG GROUND MOTION IN THE COYOTE LAKE, CALIFORNIA,EARTHQUAKE OF 1979

The effect of alluvium on strong ground motion

Application of traditional seismological

of America, v. 71, no. 4, p. 1333-1349. By W. B. Joyner, R. E. Warrick,

for and T. E. Fumal

the conclusion peak horizontal peai<

that the velocity in the

WESTERN HEMISPHERE STRONG-MOTION

This list hemisphere strong-motion stations that have been installed and are maintained by many different organizations. It contains infor1 nation on all of those stations for which there is some data in the files of the USGS, but the list is incomplete even for stations in the United States. maintained are continuously changing, it is impossible to have complete information about all of the stations at any one time. The objective is to provide the community of persons who have an interest in strong-motion programs with an indication of the current status of the networks in this part of the world. Strong Motion Information Retrieval System (Sivlii::ZS), which permits information about the strong-motion stations, records, and events. In general, the infor1 nation in SIVIIH.. S is more current than the information in this list.

For convenience, the list has been arranged by country, north to south, alphabetically by states in the section for the United States, and then alphabetically by station name. Subsequent sections include a list by stations numbers, a cross-reference of obsolete station names, and a cross-reference of three character designations for those who find that form of station designation useful. A list of the stations that were installed as required by a local building code or that are maintained by the owner of the facility appears in an appendix. That list has not been updated since 1976, at which time the USGS stopped receiving information about new installations required by building codes.

Reference: U.S. Geological Survey Open-File Report 81-664, 162 p.

ANOMALOUS FREE-FIELD RECORDINGS AT

Accelerographs are used to measure both the "free-field" motion of the ground during an earthquake and the motion of points on a structure. In general free-field accelerograms exhibit a somewhat random signal and to the eye show no particular character or dominant frequency. spectral analysis. However, occasionally a record. is obtained that does not fit this general pattern. It is then generally difficult to decide if the record is true or spurious. The record may indeed be true and may be the result of a highly unusual local terrain, that is, there may be a large underground rock lying in a low-velocity medium nearby or an underground cavity, trench, or tunnel of such dimensions so as to impose an atypical character on the record. A low-velocity layer overlying rock may produce a dominant surface wave.

ACCELEROGRAPH STATION LIST, 1980

By J. Switzer, D. Johnson, R. Maley,

The USGS also maintains a computerized

CERTAIN ACCELEROGRAPH LOCATIONS

contains information on western

Since the stations being

searching for various types of

1:3y G. N. Bycroft

This is better shown by a On the other hand, the record may be anomalous because of instrument malfunction, improper or loose mounting, or local noise. The recording may appear to be normal but actually has been compromised by soil-structure interaction.

For convenience, instruments are often located in the basement of buildings. In this case the motion of the structure rnodifies the free-field motion. fvlany studies have been rnade that show soil-structure interaction in certain cases has a substantial effect on the motion of the foundation and hence on any recordings made there.

In this report some examples are given of selected records that are suspect or show evidence of soil-structure interaction.

Reference: U.S. Geological Survey Open-File Report 82-318, 40 p.

ANOMALOUS RECORD OF OCTOBER 15,1979, IMPERIAL VALLEY,CALIFORNIA,EARTHQUAKE FROM COACHELLA CANAL ENGINE HOUSE NO. 4

A recording obtained at the Coachella Canal Engine House No. 4 of the October 15, 1979, Imperial Valley earthquake shows a dominant 2 Hz frequency. This feature is very unusual and an attempt has been made to determine if the recording is real or spurious. Because the pumping station is a small heavily constructed bunker-type structure located on material of low shear-wave velocity, it was considered likely that soil-structure interaction might be responsible for the 2-Hz component. However, both an experimental and theoretical investigation failed to confirm this. This report describes the theoretical investigation. The experimental investigation is described in a separate open-file report (see previous summary).

Reference: U.S. Geological Survey Open-File Report 82-317, 13 p.

U.S. GEOLOGICAL SURVEY STRONG-MOTION

Descriptions records and the circumstances in which they were recorded earthquake engineering through the computer based Strong-Motion Information Retrieval Systern (SMIRS). The system provides ready access to information about strong-motion records and the level of processing and analysis Information recorded motion and about the sites at which the motion was recorded is also provided. The information has been arranged into several data sets. The three major data sets are the record descriptions, the

INFORMATION AND DATA

that has about t3y G. N. 1:3ycroft

NETWORK DATA

been performed earthquakes accelerograph

on them. that generated earthquake descriptions, and the recording site descriptions. instructions and information about the data base, information about the recording instruments, and identification of organizations that own strong-motion instruments, that have additional information about the recording sites, or that archive the original or processed records.

With an ordinary phone line and a keyboard terminal, users of the system may review the information free of charge. Instructions are available from the system so that a user needs to know only how to dial the computer and what to type to enter the retrieval system and begin using it. Once accessed, the system will offer a general introduction and will tell the instructions. opportunity to request a copy of the printed user's manual.

The best SMIRS telephone number to use will depend on where the user's office is located and on the transmission speed of the terminal that will be used. In most locations, users should dial a number in the TYMNET telecommunications network in order to access the computer without incurring a long-distance telephone charge. TYMNET Corporation maintains local telephone numbers in many cities in the United States and in several foreign countries. TYiVINET phone corporation's Western Customer Service at (800) 323-7389 or TYMNET Customer Support Group at (800) 366-0149.

SMIRS resides in one of the USGS computers in Denver Colorado. Users located near Denver may dial the computer directly using one of the following telephone numbers:

Whenever the computer is not operational, the tape-recorded status message will let you know when the computer is expected to be operational again.

Users located near Menlo Park, California, may also dial a local number and directly access the Denver computer. The Menlo Park numbers are:

(415) 329-8600 (415) 329-8597, 98 for 1200 baud 1:3ELL

(415) 329-8550 through 65

Take the following steps to access SMIRS.

user how The user also will be given an

for other 1200 baud

Set the switches, keys, or buttons on the terminal that allow a choice of operating modes:

transmission speed, for 300 baud moderns such

for 1200 baud moderns such

for 1200 baud BELL 2l2a

for 300 baud modems, data

as those included in the TI Silent 700 terminals,

as the VADIC moderns,

message giving the status of the computer.

modems.

characters second) or include

baud per on line; lower case ASCII characters; and full duplex (if you are going to dial a TYMNC:T number) or half duplex (if you are going to dial Denver directly). 2)

Plug in and turn on the terminal; turn on the modern if it is a separate device. Notice whether the modern uses an acoustic coupler or whether the modem is directly connected to a telephone. An acoustic coupler wiH have a cradle into which a telephone handset can be inserted. Look for a label or diagram on an acoustic coupler that will show you in which direct.ion the telephone cord should go. A direct-connect modem will have a switch that can be set for voice or data transmission. 3)

Dial the USGS computer number in Uenver or dial the TYMNET number nearest you; wait for a high-pitched tone. 4)

Place the telephone handset in the cradle on the direct-connect switch to "data." Wait for the "carrier detect" light to turn on; this indicates that the terminal is receiving a signal from the computer or from the TYMNET equipment. 5)

If you are using TYMNET, the TYMNET prompts response (shown in italics here) should proceed as follows:

Type the line-feed key. The computer wiil respond with several lines that will tell you which computer you have accessed, how many other users are connected, and so forth. 7a) If your terminal will transmit both upper and lowercase characters type: 1200 baud;

please type your terminal identifier please log in: <CR>

The <CR> symbol represents the carriage-return key.

Do not be alarmed when the first prompt comes at an odd speed.

TYMNET will now connect your terminal to the computer in Denver. computer is operating, "USGS is online" will be printed at your terminal.

where <CR > is the carriage-return key and <your name> is your own name typed-without any embedded blanks.

Note that the word "enter" is in lower case and "SIVIIRS" is in upper case. or set

here);

If the 7b)

Don't be concerned if the computer does not respond immediately after you enter SiVIIHS. The response time may improve in the future, but it will always be fastest during nonworking hours (l.Jenver time).

CALIFORNIA DIVISION OF MINES AND GEO.OGY

Processed strong-motion data from selected earthquakes are available from the California Division of tvlines and Geology (CDMG). The data have been prepared by the interim CDMG strong-motion data processing system. This system is composed of a series of programs that have been developed by the California Institute of Technology, the USGS , and the CDMG, with special emphasis on the handling of longduration film records from multiple-channel central recording instruments.

The data are grouped by phase:

Phase I Phase II

Phase III Each phase contains three-channel subgroups arranged by station. At the present time, data from the following earthquakes have been processed:

Santa Barbara earthquake of August 13, 1978

UCSB Goleta UCSI::3 North Hall Freitas Building

Imperial Valley earthquake of October 15, 1979

El Centro free-field Imperial County Services Bldg.

The data are available on standard nine-track tapes, along with a microfiche copy of the tape contents. Interested parties should contact the COMG Office of Strong-Motion Studies (see "Data Sources"). If your characters type:

The "MAP" statement instructs the computer to interpret all the alphabetic characters you will subsequently type as though they were in lowercase, except those characters that follow a left slant ().

From now on, SMIRS will prompt you whenever it expects you to type something. All the prompt lines begin and end with two dashes; answer by typing a question mark if you do not know what is expected of you.

STRONG-MOTION DATA

terminal has only uppercase

Uncorrected accelerations, Corrected accelerations, velocities, and displacements, Response spectra.

Channels It is the policy of the CDMG to make all strong-motion record data promptly available to the public in a manner consistent with good data management. Requests for copies of records, personal access to record or data files, and copies of data files should be made to the Chief, Office of Strong-Motion Studies (OSivJS), and should specify identity and medium of materials to be provided or reviewed. Desired access or delivery dates should be specific. When a request for copies of materials or personal access to files is received, OSMS staff will provide the requested material or will set an appointment time for personal review of files; the requestor will be notified immediately of any significant delay or other problems that prevent meeting the request. copying or other processing of materials will be based on the actual cost of producing and delivering the items, and OSMS will retain control of originals and master copies of all iterns.

Because of the long history of close cooperation between the United States and the Central and South American strong-motion programs, much of the data from those programs are available from the same sources as the United States data (see below). Information about strong-motion data from the Western Strong-Motion Information Retrieval System operated by the USGS.

The USGS does not attempt to obtain first- class copies of records frorn those foreign organizations that prepare data reports comparable to those prepared by the USGS. Abstracts of the data reports from such organizations are presented in this Seismic Engineering Program Report series, and through informal arrangements, copies of the data and records are made available.

EDIS/NOAA WORLDWIDE STRONG-MOTION DATA

A seismograms for dissemination to the scientific and engineering community is available from World Data Center A for Solid Earth Geophysics and the National Geophysical and Solar- Terrestrial Data Center (NGSDC). strong-motion data base include Australia, Italy, Japan, Yugoslavia. The U.S. Geological Survey has furnished records from its network of cooperative strong-motion sta- tions, including those in Central and South America.

Copies of strong-motion records are avail- able on 35-mm film, on 70-mm film chips, as paper copies, and as digitized data on punched cards or ill81jnetic tape. A list of most records can be obtained from the World Data Center A publication "Catalog of Seismograms and Strong- Motion Records," keport SE-6. catalog can be ordered from NGSUC (ElJIS/NOAA) for $3.00 (see "Data Sources").

The recorded in the United States and Latin America between 1931 and 1971 have been copied on seven reels of 35-mm film (x 12 reduction) and 70-mm film

FOREIGN STRONG-MOTION DATA

and chi~s (approximately x8 reduction). The film chips are available for $1.50 per chip; longer records are continued on additional chips. The 35-mrn film copies can be purchased for $30 per reel, the complete set of reels for $180. There is a minimum charge of $10 per order.

_J~~an and Australia have supplied magnetic tapes of digitized data from stations located in the western Pacific Ocean (the Japanese Islands, New Guinea and New Britain). A series of 400 United S~ates strong-motion records (1933-71) were digitized by the California Institute of Technology and are now available on six magnetic tapes. The USGS is digitizing post-1971 records from its network; they have generated 15 tapes of strong-motion records recorded from 1967 to 1975 in the United States Chile, Nicaragua, San Salvador, and Mexico. ' Other digitized data include punched cards containing strong-motion records frorn the March 4, 1977, ear_thquake in Rumania (recorded in Bucharest); the GazlJ earthquake of May 17, 1976, in Uzbek, U.S.S.R.; and three earthquakes in the New Madrid seismic zone (located in midcontinental United States) in 1975 and 1976.

Recent acquisitions include a magnetic tape of strong-motion records triggered by a swarm of earthquakes that occurred in northern Italy near the town of Friuli in 1976; these were compiled by the National Commission for Nuclear Energy and have been given to the center for distribution. Other data include records obtained frmn California earthquakes near Santa Barbara in August 1978, Gilroy in August 1979, El Centro in October 1979, and Livermore in January 1980.

A table listing all digitized strong-motion records available on magnetic tape may be obtained free of charge frolll ELJISJNUAA. Digi- tized strong-motion records may be purchased either in punched card format at $60 per record (including all three instrument components) or in tape forrnat at $80 per tape.

Checks or money orders should be made payable to "CommercejNOAA/NGSDC"; inquiries should be addressed to EUIS/NOAA (see "Data Sources"). strong-motion records and data, address inquiries to the appropriate agency listed below:

I.

DATA SOURCES

For reports or information

604 So. Pickett Street Alexandria, VA 22304

Earthquake Engineering Research Institute 2620 Telegraph Avenue Berkeley, CA 94704

EUISJNOAA National Geophysical Data Center (D622) Boulder, CO 80303

National Technical Information Service 5285 Port Royal Road U.S. Dept. of Commerce Springfield, VA 22161

NISEEJComputer Applications (415) 642-5113 519 Davis Hall, UC Berkeley Berkeley, CA 94720.

Office of Strong-fvlotion Studies California Division of Mines and Geology 2811 "0" Street Sacramento, c:;A 95816

Open-File Services Section Branch of Distribution

Box 25425, Federal Center Denver, CO 80225

Seismic Engineering Branch U.S. Geolog! :::al Survey 345 Middlefield Road, MS 78 Menlo Park, CA 94025. regarding

(804) 756-6141 (FTS) 756-6141

(303) 497-6764 (FTS) 320-6764

(703) 487-4650 (FTS) 737-4650

(916) 322-3105 (FTS) 552-3105

(303) 234-5888 (FTS) 234-5888

(415) 323-8111 ext 2881 (FTS) 467-2881

Bear Valley: Sta. 10 Webb Residence (USGS) ~-t2 Direction Station

coord.

1-peak

u. 15

Table l. - Summary of acceZerograms recovered during September - December 1980 - continued

9 October 19 79- 28 September 1980 So. Hawaii Epicenters and magnitudes unknown

l3 October 1980 0246 UTC Central California

1-peaK

Table l. - Summary of accelerograms recovered during September- December 1980- continued

* DurationS

Table l. - Surrrmary of accelerograms recovered during September - December 1980 - continued

5 August 1980- 10 December 1980 Central California Epicenter and magnitude unknown

1 Station owner code: ACOE - U.S. Army Corps of Engineers. CDWR - California Department of Water Resources. USGS - U.S. Geological Survey. WPRS - U.S. Water and Power Research Service. t- WWVB time code not legible or instrument not equipped with a radio receiver, correlation of accelerogram with event may be questionable.

2 S-wave arrival minus trigger time (S - t) interval. * S-t time is questionable or cannot be aeterrnined .

.3 Direction of case acceleration for upward trace deflection on accelerogram. Horizontal components are listed as azimuth in degrees clockwise from nortn. Vertical components are listed as UP or "down ...

4 Peak acceleration recorded at ground level on one vertical and two orthogonal horizontal components unless otherwise noted. ** Denotes maximum acceleration is less than U.05 ~ at ground level or less than 0.10 ~at non ground-level stations.

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