sc ec california earthquake centerscecinfo.usc.edu/news/newsletter/issue12.pdf · san andreas fault...

SS CC EE CCSouthern

CaliforniaEarthquake

Center

Quarterly Newsletter

Volume 1, Number 2

Inside this Issue...See Back Page

USGS ScientistsTrench AcrossSan Andreas Fault

See "Trenching" on Page 3

n May, geologists Tom Fumal and MichaelRymer of the United States Geological Survey(USGS) in Menlo Park, excavated twotrenches across the San Andreas fault at anoasis and nature preserve just east of Thou-sand Palms, California. The fault forms awater barrier, which led to formation of theoasis. The Nature Conservancy manages thepreserve and was supportive of the investiga-tion.

The trenches expose a beautiful layeredsequence of alluvial deposits and peats andcontain evidence of the past two largemagnitude earthquakes on this part of thefault (see photos, page 3). The older eventproduced intense warping of the peats andfissuring of the deposits in the lower part ofthe trenches. The most recent event extendsto within 30 centimeters of the presentground surface and is expressed as a broad

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Summer 1995

Dating results will providenew information forprobability estimates offuture earthquakes.

Inquisitive reporters observe USGS scientists Tom Fumal and David Schwartz in trench nearThousand Palms, California.

Southern California Earthquake CenterSS CC EE CC

From the Center Directors...From the Center Directors...From the Center Directors...From the Center Directors...From the Center Directors... Keiiti AkiScience Director

Thomas HenyeyExecutive Director

What Is the Southern California Earthquake Center?

t’s time to pass the baton!One of us (KA) is steppingdown after five years as SCECDirector. Retirement from full-time academic responsibilitiesand the desire to pursue newfrontiers are the reasons. Thesepast five years have seen theCenter develop into a nation-ally and internationallyrecognized enterprise, withscience being practiced in anon-traditional, multi-disciplinary mode. Methodsdeveloped here may helpchange the way earthquakehazards research is done insouthern California andelsewhere in the future.

We believe that the impendingchange in directorship

I represents a new opportunityfor SCEC--an opportunity tomeld early visions of the centerwith newer ones, at a timewhen perceptions of scienceand its role in modern societyappear to be evolving. Wemust do more with less; re-orient to a more “applied”approach (which seems toimply shorter time-framesbetween ideas and “products”);and do an increasingly betterjob of reaching our “end-users”. We find that therelevance of our science andour mission as currentlystructured is under greaterscrutiny. These and otherissues will provide challengesfor the new director.

A correction to astatement in thiscolumn in the lastnewsletter: Passingour third-year reviewdid not guarantee us afull 11 years of fundingfrom NSF. We mustpass the sixth-yearreview first!

A Changing of the

Guard...

T he Southern California Earthquake Center (SCEC) activelycoordinates research on Los Angeles region earthquake hazardsand focuses on applying earth sciences to earthquake hazardreduction. Founded in 1991, SCEC is a National ScienceFoundation (NSF) Science and Technology Center withadministrative and program offices located at the University ofSouthern California. It is co-funded by the United StatesGeological Survey (USGS). The Education and KnowledgeTransfer programs are co-funded by the Federal EmergencyManagement Agency (FEMA). The Center’s primary objective isto develop a “Master Model” of earthquakes in southernCalifornia by integrating various earth science data throughprobabilistic seismic hazard analysis. The SCEC promotesearthquake hazard reduction by:

• Defining, through research, when and where future damaging earthquakes will occur in southern California;• Calculating the expected ground motions; and,• Communicating this information to the public.

To date, SCEC scientists have focused on the region’s earthquakepotential. Representing several disciplines in the earth sciences,these scientists are conducting separate but related researchprojects with results that can be pieced together to provide someanswers to questions such as where the active faults are, how oftenthey slip, and what size earthquakes they can be expected toproduce. Future work will consider seismic wave path effectsand local site conditions for developing a complete seismichazard assessment of southern California.

We hope to welcome a newdirector to the Center as soonas possible. During thetransition, TH will remain asExecutive Director, to ensurethat day-to-day operationscontinue smoothly. Once anew director is in place, THwill serve in whatever capacitythe Board and Director deemappropriate in the future.

Next year’s budgeting processbegins with the annual meetingin September and culminateswith the funding of our FY1996 program in February. The

following June (our sixth year),we will submit our final five-year science plan to the NSFand USGS for review. Theseprograms and plans will havethe stamp of the new director.And we hope that by the nextquarterly newsletter, thiscolumn will have the stamp ofa new author!

warp and minor brittle verticaldisplacement of silts andsands.

The earthquake history of thispart of the San Andreas fault isnot well known. Previouswork near Indio, California, byKerry Sieh of Caltech, suggeststhe past two large earthquakesoccurred around 1680 and 1450AD. Radiocarbon dating of thepeats and abundant charcoal inthe new Thousand Palmtrenches will put much tighterconstraints on their timing. Isit possible that rupture fromthe 1812 earthquake, which isobserved at Wrightwood,extends this far south? Thedating results, which should beavailable in August, 1995, willprovide critical new informa-tion for segmentation models,and probability estimates offuture earthquakes for this partof the San Andreas fault.

David P. SchwartzUS Geological Survey345 Middlefield Rd. MS 977Menlo Park, CA 94025

Trenching...

Clockwise from above: 1) View looking South along San Andreas Fault at fenced-off trenches(foreground) and oasis palms. 2) Stratified trench deposits showing broad warp and verticalseparation produced by most recent large earthquake on the southern San Andreas Fault. 3)View of trench wall showing evidence of the past two large magnitude earthquakes on thesouthern San Andreas Fault.


Quarter FaultQuarter FaultQuarter FaultQuarter FaultQuarter Fault Each Issue of the SCEC Newsletter will feature a southernCalifornia fault. In this issue, we feature...

t’s such an unlikely thought: that faults can create great wealth.But from west Newport in Orange County to the Cheviot hillsnear the northern end of the L.A. basin, billions of dollars worthof oil have pooled against the Newport-Inglewood’s shale smearsand under its associated anticlines. It’s estimated that along thefault’s 70 kilometer length, the sediments may yield as much as3.2 billion barrels of oil.

In addition to trapping much of L.A.’s oil the Newport-Inglewoodhas also killed more people than any fault in the region so far thiscentury. On 10 March 1933, the ML 6.3 earthquake left 120 peopledead. But of course, wherever there is active tectonics there isalso always beauty.

Moving at a rate of 0.6 mm/yr. with a right-lateral post-Mioceneoffset of 1-2 km, the modern Newport-Inglewood has brought upa series of pleasant hills and plateaus along the southwesternedge of the Los Angeles Basin, along what otherwise would havebeen monotonously flat land. On the Costa Mesa plateau, model

plane enthusiasts launch their buzzing plastic over the Santa Anariver, while on the Huntington Beach plateau surfers ride horsesunder eucalyptus and palm, on hot days when the sea has goneflat. The Newport-Inglewood is also responsible for other similarstructures, such as Signal Hill, Dominguez Hills, and BaldwinHills.

The photo shows the Newport-Inglewood fault crossing WarnerBlvd. in Huntington Beach, beside the Bolsa Chica wetlands. Thefault runs along the base of the hill (roughly where the cyclists arepedaling). For decades, local high schoolers have run down thefault scarp’s edge at night (to the east of the photo), headedtowards the wetland pools and hidden nooks to do what highschoolers do on warm summer nights, never suspecting that theHuntington Beach oil fields under their feet will probably yield1.1 billion barrels of oil nor that they are running up and down anactive fault. One usually has other much more important andserious things to think about at fifteen than to wonder about oil orthe nature of hills.

Michael Forrest

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The Newport-Inglewood Fault

Warner Boulevardjust north ofPacific CoastHighway inHuntington Beach.The right lateralNewport-Inglewood Faultruns at the foot ofthe hill, roughlywhere the cyclistsare pedaling.

Earthquake Map Now Available fromthe U.S. Geological Survey

“Earthquakes in California and Nevada” depicts theepicenters of 300,000 earthquakes, including 49 ofmagnitude 6.5 or larger that have occurred in thetwo-state area since 1836. The earthquakeepicenters are depicted by various sizes of opencircles and red dots.

Different elevations, from two miles below sea level to thetallest peaks of the Sierra, all water courses such as rivers,streams, lakes and reservoirs, and all major highways aredepicted. The map offers a ready reference for areas thathave had few if any earthquakes during the past 160 years.California’s great central valley, for instance, has only a fewdots depicting earthquake epicenters.

The California-Nevada map contains new information, suchas epicenters of the Loma Prieta, Landers, Big Bear andNorthridge earthquakes that have occurred since the firstCalifornia earthquake map in the series was published in1988. The map, priced at $12 for a paper copy or $22 for alaminated copy, including shipping costs, is available bymail only from:

Earthquake MapsU.S. Geological Survey

Box 25046, Federal Center, MS 967Denver, CO 80225

Orders must include the name and number of the map“Earthquakes in California and Nevada; Open-File Report94-647”, and a check or money order, payable to DOI/USGS.

Master Model Progress:

the SCEC Phase III Report

he Center’s Phase II report, “Seismic Hazards in SouthernCalifornia: Probable Earthquakes, 1994 - 2024”, was primarilyconcerned with the characterization of earthquake sources insouthern California. For the Phase III report, we will include thesource effect, the effects of local geologic and topographic siteconditions, as well as the propagation path effect on strongground motion. The report will be in two parts: One for produc-ing probabilistic seismic hazard maps for the entire southernCalifornia area; and the other for developing consensus timehistories for selected earthquake scenarios and recording sites insouthern California.

The first part will rely on some available empirical formulas ofattenuation relations, and will attempt to divide southernCalifornia into site classes, to be adopted into each formula. Thesite classification will be carried out by combining information onsurface geology, seismic velocity profiles, and amplificationfactors for strong and weak ground motion that have beenempirically determined for strong motion seismograph sites aswell as numerous regional network stations. We shall usemultiple empirical attenuation relations by various authors inorder to find the range of variation in the hazard estimate.

The second part of the report will include computation of timeseries of ground motion by seismologists at a number of institu-tions (universities, governments and private consultants) forselected earthquake scenarios and recording sites. In general, adeterministic source modeling is used for periods longer thanabout one second, and a stochastic source modeling for shorterperiods. Each institution uses different assumptions,parameterizations and ways of combining the deterministic partwith the stochastic part. Each modeling approach will be vali-dated using the data from recent earthquakes in southernCalifornia. The resulting range of predicted ground motion forfuture earthquake scenarios will represent the range of uncer-tainty in the current state-of-the-art.

The outcome of the second part can be used for a spot check of themap produced by the first part. The comparison of predictionbetween the empirical approach taken in the first part and thephysical modeling approach taken in the second part, will offeranother measure of uncertainty in our prediction. The target datefor the completion of the Phase III report in the reviewable formatis Spring, 1996.

We plan that the report will be the core of accomplishmentspresented in the next five-year renewal proposal to the NationalScience Foundation.

Keiiti Aki

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NOVA Documentary Available

PBS recently aired a NOVA program covering theNorthridge Earthquake and the future earthquake risk tothe greater Los Angeles area, emphasizing blind thrustearthquakes. The program, entitled "Killer Quake,"features several SCEC scientists. A video copy of theshow can be ordered from NOVA by calling 1-800-255-9424, at a cost of $19.95. Footage of the Northridge, LongBeach, and other California earthquakes at the time ofshaking or very soon thereafter is quite spectacular.


See "PBIC" on Page 8

Satellite Infrastructure CentersSatellite Infrastructure CentersSatellite Infrastructure CentersSatellite Infrastructure CentersSatellite Infrastructure Centers

The Portable Broadband Instrument Center (PBIC)

The PBIC is managed by the Institute for Crustal Studies at theUniversity of California’s Santa Barbara Campus by RalphArchuleta. Technical staff members are Aaron Martin and PeterRodgers. Martin provides technical and support services for theSCEC equipment as well as software development and fieldsupport at the investigator’s request. Rodgers provides a widerange of expertise in the area of seismic instrumentation fromequipment specifications to calibration procedures. Rodgers andMartin, along with engineers from other California institutions,developed a procedure for calibrating that is now routinely usedon all SCEC electromagnetic sensors. A paper describing the

he Portable Broadband Instrument Center (PBIC) was estab-lished by SCEC to provide researchers with year–round access toa “pool” of high–resolution, digital seismic recording equipment.Since its establishment in 1991, the PBIC has been involved inthree significant aftershock deployments and about 30 SCECexperiments (see figure this page). PBIC instruments haverecorded gigabytes of data each year. Its technical personnel haveprovided valuable support to SCEC researchers and have signifi-cantly improved sensor calibration. The data collected byresearchers using PBIC equipment has been used to investigate anumber of problems relating directly to the SCEC Master Model.

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As part of its infrastructure, SCEC maintains a number of data and instrument centers at its core institutions.Each quarterly newsletter will highlight one or more individual centers. In this second newsletter we describethe Portable Broadband Instrument Center (PBIC) at the University of California, Santa Barbara, and the Geo-graphical Information System (GIS) Facility at the University of California, Riverside.

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Experiments using PBIC equipment

to date

The SCEC GIS Facility has recently moved into a new computerlab on the UCR Campus. The new lab allows centralization ofpersonnel and resources. Partnerships with the rapidly-expand-ing USGS SCAMP GIS project and the UCR Center for VisualComputing promote the combining of resources to producequality GIS products in a more timely manner. (SCAMP is theUSGS Southern California Areal Mapping Project. It is part of theNational Geologic Mapping project, using a 1:100,000 scale, andwill also produce geochemical, age dating, magnetics and gravitymaps.)

Database Development

Advanced database development includes the active structuresdatabase, which has produced the popular Alquist-Priolo faultsdataset for southern California. This fault dataset provided thebase structure for development of a regional active structuresdatabase. Through sponsored workshops and a partnership withthe USGS, scientists are identifying additional high quality datasources for this database. Beyond spatial extent of active struc-tures, the SCEC GIS Facility is beginning to apply new tabularinformation to its database. Tables have been imported fromMark Peterson (USGS Menlo Park) and Steve Wesnousky(University of Nevada, Reno) into a database managementsystem. Positional information within these tables will allowflexibility in connecting fault information in spatial format. Thiswill facilitate future data input.

Also under construction is a dataset of the offshore activestructures from maps supplied by Mark Legg, Senior Scientist,ACTA, Inc., and will be available as an independent dataset aswell as integrated into the active structures database.

T he SCEC GIS Facility, located at the University of California,Riverside (UCR), provides GIS support and develops geologicdatabases for use by SCEC scientists and for the Center as awhole. The Facility also enhances knowledge transfer byproviding SCEC databases in a GIS format for end users ingovernment and industry, and provides education and training ofGIS personnel within both SCEC and the USGS.

Geographical Information System

(GIS) Facility

With SCEC GIS support, the SCAMP GIS project will produce adigitized version of southern California geology. This databaseand its future products are in the early stages of development. Todevelop GIS maps for the SCEC Phase III report, surficial geologymaps for the Los Angeles and San Fernando basins are now underconstruction.

Database Access

Through the SCEC World Wide Web Page, the SCEC GIS Facilitywill make available well-developed GIS databases via an onlinepoint-and-click catalog. This will eliminate time currently spentproviding copies of databases via magnetic media while allowingadvertisement of the databases now available. An experimentalSCEC GIS Facility WWW page featuring the Alquist-Priolo faultdatabase is currently running (http://vortex.ucr.edu). A completedSCEC WWW Page will be ready by summer’s end. For those whodo not have access to WWW browsers, the GIS Facility will bedeveloping a “smart” ftp server in parallel with the WWW Page.The “smart” ftp server will instruct users in accessing onlinedatabases with UNIX ftp.

Future Projects

The SCEC GIS Facility will be developing software tools for usewith databases in order to facilitate the use of Arc/Info. The toolswill also provide a mechanism for executing seismic hazardmodels with Arc/Info.

For more information:

SCEC GIS FacilityDepartment of Earth SciencesUniversity of California at RiversideRiverside, CA 92521(909) 787-4501(909) 787-4324 [email protected] (Steve Park)[email protected] (Eric Lehmer)

Eric Lehmer


procedure was recently published in the June 1995 issue of theBulletin of the Seismological Society of America. (Reprints areavailable on request from the PBIC.)

The PBIC currently has 16 sets of equipment and should realize itsoriginal goal of 20-25 sets within a couple of years. A PBIC setincludes: a REFTEK 72A-02 or 72A-08 Data Acquisition System(DAS), an FBA-23 triaxial force balanced accelerometer and anL4C-3D, high-output, triaxial velocity transducer, with highcapacity gel cell batteries coupled to solar panels or smallercapacity gel cell batteries coupled to small AC chargers. Supportequipment such as interface terminals and mass data transferdevices are provided as well. Equipment purchasingspecifications are reviewed yearly by an ad hoc committeecomprised of members from SCEC member institutions.

Suitable for a wide range of experiments, PBIC equipment has

been used to record data for experiments in seismic refraction, siteresponse, earthquake aftershock sequences, guided waves,empirical Green’s functions and teleseismic recording. The SCECequipment is in the field about 90% of the time. Many of theexperiments are supported by agencies other than SCEC. ThePBIC provides the instrumentation and its support, while fundingfor salary and analysis comes from other sources.

A typical example of the partnership between SCEC and otheragencies is the UCSB/USC Los Angeles Microzonation experi-ment. This cooperative experiment, directed by Jamison Steidl(Assistant Research seismologist, UCSB ICS) and James Chin(USC), uses equipment from SCEC, Caltrans and PASSCAL and isfunded by the USGS, SCEC, UCSB and Caltrans. While deployedfor this experiment three of the PBIC FBAs recorded theNorthridge mainshock (see figure this page).

PBIC...

In a specific experiment to correlate ground motion and damage,SCEC and USGS personnel deployed 30 sets of instruments in a 2-km x 2-km area near the Northridge Fashion Center about onemonth after the Northridge mainshock. As part of the SCEC/USGS LARSE (Los Angeles Regional Seismic Experiment), thePBIC deployed all of its instruments, assisted in the deploymentof the hundreds of PASSCAL recorders, and calibrated most of thesensors. In 1994 the PBIC collected more than 5.6 Gb of data; in1995 the PBIC has already collected more than 3.9 Gb of data. Allof the PBIC data are being fully integrated into the SCEC datacenter.

Aaron Martin

For more information about the PBIC contact Martin by phone at (805)893-8415 or by email: [email protected]. The PBIC has estab-lished a WWW page: http://quake.crustal.ucsb.edu/scec/pbic/pbic.html.

One of the most important justifications for the PBIC equipment isSCEC’s interest in responding quickly to aftershock sequencesfrom significant earthquakes in southern California. In the case ofthe Joshua Tree and Landers/Big Bear earthquakes, the PBICrecords supplement the phase information of the widely-spacedSouthern California Seismic Network (SCSN) stations. InNorthridge, sites were selected to complement the permanentstrong motion stations, i.e., record aftershocks to be used later asempirical Green’s functions, to compare weak and strong motion,and to determine site response, especially for the San Fernandoand Los Angeles basins. The other high priority was to recordstrong motions as close to the source as possible. An excellentexample is shown in the figure below where 0.81 g accelerationwas recorded at the PBIC station BRCY from a M 5.1 aftershock.Note that the S-P time is about 0.75 s, indicating a distance of lessthan 6 km.


The complete SCEC scientists' publications listing is updated and available on a continuous basis. Pleasecontact the SCEC Administrative Office, 213/740-5843, to obtain updated listings. Selected publicationsmay be available through the Center; however, to obtain authorized copies of preprints or reprints, pleasecontact the authors directly. The Spring 1995 quarterly newsletter includes all publications; subsequentissues will include newly submitted papers only.

SCEC Scientists' Publications, Spring 1995SCEC Scientists' Publications, Spring 1995SCEC Scientists' Publications, Spring 1995SCEC Scientists' Publications, Spring 1995SCEC Scientists' Publications, Spring 1995

214. Gao, S.; Liu, H; Davis, P.M.; and Knopoff, L., LocalizedAmplification of SeismicWaves and Correlation withDamage Due to the NorthridgeEarthquake, submitted toBulletin of Seismological Societyof America, February, 1995.

215. Abercrombie, Rachel E.,D. Agnew, F. Wyatt, Testing aModel of EarthquakeNucleation, Bulletin ofSeismological Society of America,in press, May, 1995.

207. Davis, Paul M. and LeonKnopoff, The Elastic Modulusof Media Containing StronglyInteracting Antiplane Cracks,Journal of Geophysical Research,in press.

208. Manov, Derek V., RachelE. Abercrombie, and Peter C.Leary, Reliable and EconomicalHigh Temperature DeepBorehole Seismic Recording,submitted to the Bulletin of theSeismological Society of America,March 1995.

209. Abercrombie, Rachel E.,The Magnitude-FrequencyDistribution of EarthquakesRecorded with DeepSeismometers at Cajon Pass,

Southern California,submitted to Tectonophysics,March 1995.

210. McNeilan, T., Rockwell,T. K., and Resnick, G., 1995 inreview, Sense and Rate ofHolocene slip, Palos VerdesFault, Southern California:submitted to Journal ofGeophysical Research, March,1995.

211. Lindvall, S. andRockwell, T. K., 1995 inreview, Holocene activity ofthe Rose Canyon Fault, SanDiego, California: submittedto Journal of GeophysicalResearch, March, 1995.

212. Minster, Jean-Bernard H.,Nadya P. Williams, T. GuyMasters, J. Freeman Gilbert andJennifer S. Haase, Applicationof Evolutionary Programmingto Earthquake HypocenterDetermination, EditedProceedings of the 4th AnnualConference on EvolutionaryProgramming, MIT Press, 1995.

213. Nielsen, Stefan, LeonKnopoff and Albert Tarantola,Model of EarthquakeRecurrence: Role of ElasticWave Radiation, Relaxation ofFriction and Inhomogeneity,Journal of Geophysical Research,in press, 1995.

The dense network was deployed in the area of heavy damage.The seismologists were fortunate in that the 98 REFTEK digitalrecorders just “happened” to be available from an independentIncorporated Research Institutions for Seismology (IRIS) researchprogram when the Northridge earthquake occurred. They werealso ingenious in their method of deployment. An advertisementwas placed in the university newspaper for volunteers whowould allow a seismograph to be placed in the back yards of theirhomes. They received more than 100 responses and were able tochoose sites along two N-S profiles from the San Fernando Valleyacross the Santa Monica Mountain to the Los Angeles Basin, aswell as two clusters covering the severely damaged areas inSherman Oaks and Santa Monica.

UCLA seismologists, under the leadership of Paul Davis,deployed 98 seismic stations to record aftershocks of theJanuary 17, 1994 Northridge earthquake.

Localized Amplification of Seismic Waves and Correlation With DamageDue to the Northridge Earthquake

Results of the preliminary analysis of the large amount of datacollected will be described in a paper by S. Gao, H. Liu, P.M.Davis and L. Knopoff in the special issue of the Bulletin of theSeismological Society of America on the Northridge Earthquake(expected to appear in January, 1996). They found a significantcorrelation between peak ground motion of the aftershocks anddamage patterns. The correlation in Santa Monica is greatest forevents originating from a restricted focal zone. Seismic wavesgenerated by these events focus in mid-Santa Monica wheredamage was greatest. This result highlights the usefulness ofsmall earthquakes data for the estimation of strong groundmotion due to large earthquakes.

Keiiti Aki

SCEC Activities...SCEC Activities...SCEC Activities...SCEC Activities...SCEC Activities...

he question as to whetherseismicity along a particularfault is described by theGutenburg-Richter relationshipor characteristic earthquakemodel is currently a hot topic,and so was the subject of aSCEC seminar held at theUniversity of California, LosAngeles on 18 May. Theseminar was hosted by DavidJackson, SCEC scientist andprincipal author of the SCECPhase II Report "SeismicHazards in Southern Califor-nia, Probable Earthquakes,1994-2024." Seminar partici-

pants included a large group ofscientists from the Los Angelesarea and beyond. The speakersand subjects covered included:

• David Jackson, Implications ofthe characteristic earthquakemodel• Arch Johnston, Estimating themaximum earthquake magnitude• Yan Kagan, Regional varia-tions of maximum magnitude, b-value, and seismicity• Mark Stirling, Magnitude-frequency distributions of strike-slip faults: a global survey• Charlie Rubin, Evidence for

very large earthquakes on not verylarge faults• Barbara Romanowicz,Magnitude, fault length, andscaling relationships• Leon Knopoff, Magnitudedistributions on networks of faults• David Schwartz, Fieldevidence for the characteristicearthquake model

From the general discussion itwas clear that the mainarguments people have againstthe characteristic earthquakemodel are that (1) any faultcould show seismicity consis-

tent with the Gutenburg-Richter relationship if a largeenough maximum-sizeearthquake were defined alongit, and (2), that there is gener-ally too much uncertainty inmaximum earthquake size andrecurrence rate on faults for theearthquakes to be consideredtruly characteristic.

However, it was shown thatthe maximum magnitudesnecessary along many faultsfor magnitude distributions tobe described by the Gutenburg-Richter relationship wouldhave to be considerably greaterthan what we would normallyestimate from fault length orarea. The second argumenthighlighted the problem ofhow scientists are using theterm characteristic earthquakemodel in different ways. Theterm has traditionally beenused to infer regularity ofearthquake size and recurrencerate, but is also now used moreloosely to describe a magni-tude-frequency distributionshape that is not log-linear atlarge magnitudes, and inwhich the moment release isdominated by the occurrence oflarge events.

The question therefore arises asto whether or not we shouldredefine the term "characteris-tic earthquake model," or useanother term for the magnitudedistribution shape that iscommonly observed alongindividual faults. The discus-sion stimulated some heartyappetites among those presentat the meeting, so the pizzasession was well attended atthe end of the day.

SCEC Seminar Report: Magnitude Distributions

T

Mark Stirling

Group discussion led by Jackson and Stirling←←



Above: Dolanexhibits trenchingdata from theElysian Park Faultproject on thegrounds of theVeteran'sAdministration inSanta Monica.

Right: Dolanpresents anoverview of thefield trip fromGriffith ParkObservatory, LosAngeles.

r. James Dolan led a groupof 47 Caltech and Jet Propul-sion Laboratory (JPL) Manage-ment Association members ona day-long SCEC-sponsoredfield trip on 8 May 1995. Titled“The Faults of Los Angeles,”the field trip was designed togive participants an overviewand technical discussion of afew major active faults in theLos Angeles Basin.

At about 8:30 am, the bus leftthe JPL parking lot andtraveled west on the Venturafreeway. Crossing the ArroyoSeco, the group viewed EagleRock, a prominent rockoutcrop on the right side of thefreeway one mile west of theArroyo. This rock, composedof Miocene Topanga Formationconglomerate, lends its nameto the Eagle Rock fault, which

runs along the steep slopealong the south edge of theVentura freeway. The faultpasses through the middle ofthe Ventura and Glendalefreeway interchange.

Along the Glendale freewaywe came out of the hills intothe broad, flat floodplain of theLos Angeles River. Dolanexplained that researchers havelong speculated that theRaymond fault systemcontinues westward andmerges with the Hollywoodfault, west of the L.A. River.Unfortunately, fluvialprocesses have obliterated anypossible scarps in thefloodplain, and a possibleRaymond fault-Hollywoodfault connection cannot beeither established or refuted bygeomorphic evidence.

James Dolan Leads Field Trip: Faults of Los Angeles

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View of Los Angeles from GriffithPark Observatory.

See "Faults of L.A."on Page 14

was uplifted as the SantaMonica Mountains rose duringsuccessive earthquakes on theblind thrust fault beneath themountains. As the mountainsrose, it became harder andharder for the river channel tocut down quickly enough tomaintain a southward gradient.Eventually this competitionbetween uplift anddowncutting resulted inabandonment of the CahuengaPass channel and the L.A.River flow switched eastwardto its present course throughdowntown Los Angeles.

In downtown Hollywood theHollywood fault, whichexhibits several strands in thisreach, is just north of, andparallel to, HollywoodBoulevard. It is especiallyprominent on Vine and IvarStreets. Dolan explained thatone of the nice things aboutstudying active faults in LosAngeles is that, although thefaults traverse one of the mostdensely urbanized areas in theworld, most of thisurbanization took place duringthe 1920s and 1930s, prior tothe widespread use ofmechanized gradingequipment. Buildings andstreets were simply built atopthe ground surface, thuspreserving the geomorphologic“signature” of active faultingfor latter-day urban geologists.

Our next stop was RunyonCanyon Park, the former site ofErrol Flynn’s estate and the

As the bus turned north ontothe Interstate-5 freeway, wesaw the eastern edge of theSanta Monica Mountains aheadand to the left as weapproached the Los Feliz exit.As we later saw at the GriffithPark Observatory stop (seephotos), the Santa MonicaMountains are essentially alarge fold that was formedabove a deeply buried,shallowly north-dipping blindthrust fault ramp. Los FelizBoulevard runs along thesouthern edge of themountains, which arecomposed of a mixture ofCretaceous granodiorite andMiocene sedimentary andvolcanic rocks.

Our first stop was the GriffithPark Observatory. We sawsome of the many hills thatring the Los Angeles basin, as

we had one of those perfectlyclear, cool Los Angelesmornings. Most of the hills,including the one on which theObservatory stands, wereformed during earthquakes ondeeply buried blind thrustfaults. The moderateMagnitude 5.9 1987 WhittierNarrows earthquake ruptureda small piece of one of theseblind thrust faults. We wereable to see the hills of East L.A.,beyond and slightly to the leftof the downtown highrisedistrict. The southern edge ofthese hills near Montebello wasuplifted about two inchesduring the 1987 earthquake.We then traveled within 20kilometers southeast of theepicenter of the Northridgeearthquake, which occurred ona previously unrecognized,south-dipping blind thrustfault beneath the northern San

Fernando Valley. Mostgeologists now believe that thefault responsible for theNorthridge earthquake is aneastern extension of the OakRidge fault system, whichextends westward for about 50kilometers, or at least as far asthe Oxnard Plain near the Cityof Ventura.

After driving down the hill, wetraveled west on Franklin. Aswe crossed Normandie, welooked right at a small hill.This is the easternmostgeomorphic expression of theHollywood fault, which wediscussed in detail later on.

As we crossed over the 101freeway, we looked toward theCahuenga Pass, where thefreeway goes through themountains. Cahuenga Pass isan old L.A. River channel that


A Visit with Scott Lindvall

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Feature: visit with a SCEC scientist

W hen the Northridgeearthquake occurred, there wasnothing that earthquakegeologist Scott Lindvallwanted to do more than get outinto the field and do somereconnaissance mapping withSan Diego State Geologyprofessor Tom Rockwell,who’d received some earlyreports about possible groundrupture.

“When you’re out in the fieldmapping a surface rupture--it’slike being a kid in a candystore. You read about things intextbooks, you read aboutthings in journal articles aboutearthquakes, but when you canactually go out and walk alongone that just happened and bein the process of documentingthat--that’s really fun,” saysLindvall about fresh ruptures.“You’re exploring.”

Following the quake, however,Lindvall's wife Dana didn’t

want him to leave the house ortheir two children.“Earthquakes terrify Dana,”says Lindvall. “She doesn'tlike earthquakes at all--eventhe aftershocks. I waschamping at the bit to get outand see what was happeningwhen Northridge hit,” saysLindvall, who reluctantly hadto tell Rockwell, “I need onemore day at home and then Ithink my family can function.”(The things we do for love.)

Fortunately for the Lindvallmarriage, major earthquakes insouthern California aren’t afrequent occurrence, and Danadoesn’t mind her husbandbeing in the earthquakebusiness. Just so long as theground beneath her feetdoesn’t move.

Lindvall received hisbachelor’s degree in geologyfrom Stanford in 1984 and hismasters degree from San Diego

State University in 1988. He isemployed by Lindvall RichterAssociates, a small earthquakesciences and engineering firmfounded in 1971 following theSan Fernando earthquake byhis father, Eric Lindvall, andCharles Richter . The firm,whose clients include the Cityof Los Angeles Department ofWater and Power, theMetropolitan Water District,The J. Paul Getty Museum, SanDiego Gas & Electric, andSCEC, has recently mergedwith Harza EngineeringCompany.

"Our office specializes inseismic hazard assessmentsand a variety of earthquakeengineering analyses ofstructures such as dams,pipelines, buildings, tanks, andeven museum artifacts," saysLindvall. “Most of the work isengineering related. I concen-trate on earthquake geologyand seismic hazards.”

best-studied part of theHollywood fault zone. Acombination of numerousMetro Rail continuously coredborings and two Los AngelesCounty storm drain trencheshave allowed scientists to mapthe fault in detail here.Researchers have also beenable to glean some preliminarypaleoseismologic informationabout the Hollywood fault.Dolan discussed some of thesepaleoseismologic results indetail at this stop. The rathersteep hill on Fuller that wewalked up as we entered thepark is a steep alluvial fan.Evidence for the most recent

earthquake on the fault isburied beneath the recently-deposited alluvial fan sedi-ments.

Dolan and other geologistsbelieve that strike-slip faultssuch as the Hollywood faultmay rupture co-seismicallywith the much larger blindthrust faults during large blindthrust earthquakes. Thisinference leads to thepossibility of understandingthe earthquake history of theblind thrust faults, whichrepresent the most seriousseismic hazards affectingmetropolitan Los Angeles.

Scientists may be able to usethe earthquake history of thesurficial faults (like theHollywood fault) as a “proxy”for the earthquake behavior ofthe blind thrust faults, which,because they are so deeplyburied, are not amenable tostandard paleoseismologictrench analysis.

After leaving Runyon CanyonPark, we drove throughportions of Beverly Hills andstopped for a picnic lunch atthe Veteran’s AdministrationHospital grounds, where weheard more about the SantaMonica fault and

paleoseismologic trench resultsfrom the site, as well as theirimplications for the seismichazard posed by the fault.

Following lunch, we took the405 freeway south to theInterstate 10 heading east. Wewere able to see the BaldwinHills ahead of us and to theright. Dolan said these hills arethe northernmost of a series ofoil-bearing uplifts along theNewport-Inglewood structuralzone (N-ISZ). Although thesouthern portion of the N-ISZis well known as a right-lateralstrike-slip fault because of theMagnitude 6.3 1933 Long

Faults of L.A. ...

Lindvall's first involvementwith SCEC was in 1991 withGroup C (Earthquake Geol-ogy), led by Kerry Sieh ofCaltech. “Actually Sieh and Ihad worked on several projectstogether,” says Lindvall, “andafter the completion of theCenter's first year, he asked meto submit a proposal to theCenter. I proposed doingresearch on the Sierra Madrefault, but shortly after begin-ning that study, the Landersearthquake struck.

"For the next couple of weeks, Imapped the Landers rupturewith the Caltech/SCEC group.The event delayed the plannedSierra Madre study andredirected my efforts to theeastern Mojave for two years. Iworked with Tom Rockwell onpaleoseismic trenchinginvestigations of the southernthree faults that ruptured in theLanders earthquake, while Siehand Charlie Rubin (SCEC

Scott Lindvall

scientist at the University ofWashington), as well as agroup from the USGS, trenchedthe rupture at several otherlocations.

"This earthquake provided agreat opportunity to test newideas about fault segmentation.The paleoseismic studies areshowing that previous rupturesinvolved multiple strands, asin the 1992 rupture, and thatrecurrence intervals for theseand other eastern Mojave faultsare on the order of severalthousand years--and could be

ruptured in the 1971 earth-quake. I’m also working withRubin on a trenching study inthe Altadena area. “

It's not surprising that L.A.Geologists are eagerly awaitingthe results of Lindvall's andRubin's work on the SierraMadre fault given its proximityto downtown Los Angeles.“As far as faults within thegreater L.A. Basin go, it’spossibly the most hazardous,”says Lindvall. “It has arelatively high slip rate and iscapable of large events.”Lindvall has a healthy respectfor the range front faults, giventhat he has twice found himselfin an area of hard shakingduring recent quakes.

“In 1971, we were living inSand Canyon which was aboutthree miles from the epicenterof the 9 February San Fernandoquake. I was nine years old,”says Lindvall. “We got out ofthe house after the main shock.Within several minutes therewere major aftershocks. One ofmy most vivid memories was

feeling the ground lunge inapparently random directionsduring the large aftershocks asmy two younger brothers and Istood outside on the concretepatio. It was more spectacularthan any ride at Disneyland.Dust was rising from eachcanyon in the mountainssurrounding us. It was anamazing experience, but itdidn’t shake as violently as theNorthridge earthquake did atour present house in Valencia.

It's somewhat amusing to thinkthat I’ve come full circle - nowstudying the Sierra Madre faultzone, the fault responsible forgenerating the 1971 event,which interested my dad, andeventually me, in earthquakegeology . . . “

Lindvall’s voice trails off as heleans back in his chair, looksout the window and smiles.

as many as ten thousand. Pastearthquakes on some faults inthe eastern Mojave shear zonealso appear to have beentemporally clustered.”

As for Lindvall's current work:“Now I'm back to researchingthe Sierra Madre fault. Weneed to quantify the slip rate,slip per event, and the timingof past events. I’m now in theSylmar area, attempting toquantify the rate of uplift ofolder stream terrace depositsby fault strands that extendinto the Basin, some of which

Beach earthquake, recentresearch by John Shaw andJohn Suppe at PrincetonUniversity indicates that thenorthern part of the N-ISZ,including the Baldwin Hills, isunderlain by a large,previously unrecognized blindthrust fault, which they havenamed the Compton-LosAlamitos fault.

We then turned north onto the110 freeway, which follows thechannel of the ancestral ArroyoSeco. Just before the freewayturns into Arroyo Parkway, itmakes a sweeping left turn upthe south side of Raymond

Hill. This is the fault scarp ofthe Raymond fault, whichproduced the Magnitude 4.9Pasadena earthquake in 1988.This left-lateral fault wasoriginally interpreted as areverse fault based on thescarp. But the 1988 Pasadenaearthquake, which showedpure left-lateral strike-slipmotion on this fault, coupledwith geomorphic evidence,indicates that it is a left-lateralfault. The scarp is here becausethis reach of the fault is in arestraining bend.

Next, we viewed Lacy Park inSan Marino, just off Virginia

Street. Lacy Park is dominatedby a large bowl-shapeddepression, which used to be aswampy lake. The lake wasthere because the Raymondfault, the scarp of which isvisible just to the north, takes abend to the left. This causes,Dolan said, what’s called areleasing bend in the fault,which we see as thetopographic depression. TheRaymond fault is active.

For the last stop of the day, thebus headed back to the JetPropulsion Laboratory. Wediscussed the nearby SierraMadre fault zone, one of the

largest faults within the LosAngeles metropolitan area.Hundreds of past earthquakeson this fault have uplifted theSan Gabriel Mountains to thenorth.

Michael Forrest

Faults of L.A. ...

Dolan's Ph.D. is from the Universityof California, Santa Cruz, where hestudied the geologic evolution of thenorthern Caribbean. During thesestudies, he became interested inearthquakes, and is involved inongoing studies of very largeearthquakes in Hispaniola and PuertoRico. For the past four years he hasbeen studying seismic hazards in theLos Angeles region. He recentlymoved from Caltech to USC, where hecontinues his research.


More SCEC Activities...More SCEC Activities...More SCEC Activities...More SCEC Activities...More SCEC Activities...

Natural Hazards Seminar Series Kickoff Presentation at the Jet Propulsion Laboratory

Visitor Control. Allow extra time to clear Visitor Control. JPL is aNASA facility operated by Caltech. Non-U.S. citizens wishing toattend please alert Ron Blom and he will aid in making arrange-ments.

For more information:Ronald G. Blom, Ph.D.Lead Scientist, Terrestrial Sciences Research ElementJet Propulsion LaboratoryMail Stop 183-501California Institute of Technology4800 Oak Grove DrivePasadena, California 91109-8099Internet: [email protected] 1-818-354-4681

The first featured speaker for the Natural Hazards Seminar serieson 15 June was Dr. John Rundle, Professor at the University ofColorado, Boulder, and Chairman of the SCEC Advisory Council.Dr. Rundle is a Distinguished Visiting Scientist at JPL. The topiche presented was "Complexity and Scaling in Natural HazardOccurrences." Future seminars are scheduled for the first Thurs-day of each month, at 2:00 pm in the 167 cafeteria conferenceroom. A schedule of speakers will be available from the SCECoffice or Ron Blom (see end of article).

JPL is located in northwestern Pasadena at 4800 Oak Grove Drive.If you drive there, exit the 210 freeway at "Berkshire/Oak GroveDrive." Turn east upon exiting the freeway and make a left turn atOak Grove Drive (T-intersection with Berkshire). Continue upOak Grove 1/2 mile to JPL. Park in the visitor’s lot and go to

The report and map of theSCEC workshop, "Geologicaland Design Issues of Continu-ous GPS Networks," is locatedon sideshow.jpl.nasa.gov in theanonymous ftp directory ~ftp/pub/SCEC.

The goal of the late Marchworkshop was to fostercommunications between thegeologists, geodesists, andmodelers working in southernCalifornia, and to plan theimplementation strategy of a250-station dense GlobalPositioning System (GPS)network in southern California.

The report is found in any ofthe following three files and isthree pages long. The post-script files were generated on aMacintosh:

John BognerDirector, Fire/Life Safety

Sony Pictures Entertainment10202 West Washington Blvd.

Culver City, CA 90232310/280-5646

specialists inconsidering thealternatives to"protecting thebottom line."Instructors willprovide innovativeideas and method-ologies which will aidattendees inunderstandingdisaster recovery andbusiness resumption.

For more information,contact the ACPSymposium Chair:

The 1995 AnnualSymposium of theAssociation ofContingencyPlanners will be heldOctober 23-24 at theRed Lion Inn, CulverCity, CA.

Workshopsscheduled arerecommended toguide businessresumption, lossprevention, andcontingencyplanning managers,coordinators, and

Save the Date...

9856 May 16 14:39Workshop_Report, MicrosoftWord 5.1

1026900 May 16 14:39Workshop_Report_PS, PostScript

7582 May 16 14:39Workshop_Report_rtf, RTFinterchange format

The network map is found inany of the following files and itis one page long:

1008694 May 16 14:39Network_Map_PS, PostScript

282240 May 16 14:39Network_Map, MacDraw Pro

For more information:Andrea Donnellan

[email protected]

Now Available: Report and Map of theSCEC GPS Workshop

Global Science Classroom ActivitiesGlobal Science Classroom ActivitiesGlobal Science Classroom ActivitiesGlobal Science Classroom ActivitiesGlobal Science Classroom Activities

Undergraduate Earthquake Education WorkshopParticipants expressed interest informing a continuing core group.The group would make additionalrecommendations on curriculum,establish multiple communicationslinks between campuses (not alldepartments have internet access),set up an electronic mail forum forquestions about earthquakes, andpool field trip guides and classexercises designed to engagestudents. Ways in which participantsfelt SCEC could support under-graduate educators included creatinga World Wide Web home pagewhereby educators could exchangesyllabi and other resources; servingas a "clearing house" to connectcommunity colleges with researcherswho want temporary student help orcould conduct a tour of a fieldexperiment; and facilitating aworkshop on computer resources inearthquake education.

Mary Templeton

This year's Annual Meeting of theCalifornia Academy of Sciencesbroke ground with a new andimportant community of earthscience faculty from nearly 30undergraduate institutions insouthern California. The SCEC-sponsored workshop, "Teaching anEarthquake Course with the Punchof a M8.0," was conducted withsupport from the FederalEmergency Management Agency(FEMA). The one-day workshop,held at California State University,Fullerton, last 6 May, provided aforum for the group of enthusiasticscientists/educators from severalcommunity colleges, state andprivate universities and two highschools. The purpose of themeeting was to get acquainted,exchange resources and identifysupport needs. The workshop waspreceded by a symposium on 5May, "The Environmental Effects ofUrban Earthquakes," whichfeatured research reports fromseismologists, social scientists andengineers.

Highlights of the workshopincluded an all-too-brief questionand answer period on earthquakeseismology, including howearthquake size is measured, anddemonstrations of physical modelsthat demonstrate earthquake-related processes. A resource tableprovided information on slide sets,maps, public domain software,internet addresses and texts.Participants also began the task ofidentifying key components of aone-semester general educationearthquake course. Thesecomponents could provide aguideline for instructors developingnew earthquake courses and couldbe prioritized to aid those whoteach earthquakes as one part of ageologic hazards or physicalgeology course.

Curt Abdouch leads classroom session←←


Global Science Classroom Activities...Global Science Classroom Activities...Global Science Classroom Activities...Global Science Classroom Activities...Global Science Classroom Activities...

SCEC Summer Intern Initiative: A Photo-Stop Report

SCEC’s second venture andadventure with undergraduatesummer interns included athree-day Technical Orientationthat transported the studentsthrough time from the Paleo-zoic to the present in theOwens Valley in the SierraNevada in California. A multi-stop/multi-experience eventwas captured by snapshots, 23-25 June. The SCEC SummerIntern Initiative focused onattracting and retainingundergraduates in the earthsciences, particularly inearthquake and active tecton-ics-related fields, is sponsoringthe research projects of 11students. The program takesspecial interest inunderrepresented minoritiesand women in these fields.This yea'rs program will besummarized in the next issueof the SCEC QuarterlyNewsletter.

Curt Abdouch

L-R standing: Michael Forrest, Andrew Byers, Mike Watkins, Ken Fowler (trip co-leader),Ryan Smith, Jason McKenna, Curt Abdouch, Carmen von Stein.L-R sitting: Mandy Johnson, Donovan Stevens.

←←

←←

Andrew ByersUC Santa Barbara

Mike Watkins,UC Santa Barbara

←← Donovan Stevens,Caltech

←←

Carmen von Stein, Central Washington University←←

←←

Mandy Johnson, USC

Ryan Smith, USC←←

Jason McKenna,UC Santa Barbara

←←

←←

In the land of glass and snow. A respite from the heat of the valley floor, although the obsidiandeposited by a volcano here was anything but cool when the eruption occurred.

Interns not pictured:

Windy Brimer, UC Santa BarbaraHeather Hodgetts, USCSusannah Pazdral, Wellesley CollegeIsabelle Sacramento-Grilo Wicks, USC


SCEC Activities...SCEC Activities...SCEC Activities...SCEC Activities...SCEC Activities...Preliminary Summary of Findingsfrom the 16 June Workshop:

Workshop on Preparing a Digital Fault and Fold Mapand Database for Southern California

In a collaborative effort,scientists from the U.S.Geological Survey, the South-ern California EarthquakeCenter (SCEC), the CaliforniaDivision of Mines and Geology,and industry are compiling adigital fault and fold map anddatabase for southern Califor-nia. The database will be animportant product of researchon active faults and earthquakepotential in southern Califor-nia. The database should bedesigned to be of maximumutility to users in research,industry, and the public.

To facilitate this goal, SCECsponsored a workshop on 29March 1995 to discuss organi-zation and construction of thedatabase. The workshopparticipants included thedatabase compilers andpotential endusers in research,industry, insurance, and localand state government. Thisdiverse group of workshopparticipants contributed todiscussions and submittedwritten comments on whatshould be included in thedatabase and how it should beorganized.

Purpose PreliminaryFindings

Earthquake Faults in Southern California

The most recent source of information about faults in California is the “Fault Activity Map of Califor-nia”. Copies may be obtained by mailing a check in the amount of $20, which covers the map andshipping, with your written request for Map #GDM-006, to:

California Division of Mines and GeologyPO Box 2980Sacramento, CA 95812-2980

The goals and interests of thepotential database users can bedivided into three maincategories:

1) Scientific Research2) Seismic Hazard3) Public Interest

Members of the first twogroups are sophisticated usersof earth science information.They expressed very specificdesires for the content of thedatabase. The third group hasdiverse interests and informa-tion needs.

Scientific researchers expresseda strong interest in using GIS(Geographic InformationSystems) technology toconstruct a Data Repository foractive faults and folds insouthern California. Theresearchers emphasized theimportance of including allavailable information such asfault parameters, references,cross-sections, trench logs, andmaps of faults at differentscales. The scientists would usethe database both as a researchtool, and to identify areaswhere further research is

needed. The researchersemphasized the importance ofincluding uncertainties alongwith data, and clearly distin-guishing between data andinterpretation.

Seismic hazard analysts werealso interested in using thedatabase as a data repositoryfor information such as faultlocation, subsurface faultgeometry, and characteristics ofsedimentary deposits. How-ever, in addition to the rawdata, these users want to obtain“consensus values” for manyof the fault parameters.Consensus slip rate valueswere identified as beingespecially important forseismic hazard calculations.The consensus values shouldbe clearly distinguishable fromthe raw data.

The third group of potentialendusers expressed widelyvarying information needs. Ingeneral, this group wants touse the database as a tool forunderstanding and utilizingearthquake information. Manyof these users would needassistance in interpreting andusing information in thedatabase. These users sug-

gested that a resource center beestablished to manage thedatabase and disseminateinformation. Some of the usersexpressed a strong interest inobtaining data in visual form,i.e. “pretty pictures” and maps.

Themes

Several themes emerged fromthe discussions and writtencomments. Participantsrecognized that developmentof the database is a majoreffort, with a potentiallysignificant impact on earth-quake research and seismichazard mitigation. In order toaccomplish this ambitious task,it is important to avoid tryingto please every potentialenduser. Rather, the compilersshould focus on efforts thatwill have the broadest impact.The first priority should be tocompile a digital fault map thatwill be accessible in a variety offormats. Workshop participantsalso emphasized the impor-tance of including both datauncertainties, and consensusvalues for fault parameters.Data and interpretation shouldbe clearly separated. The faultmap, and other databaseinformation, should beupdated on a regular basis toincorporate new research.

A more comprehensivesummary of workshopfindings will be compiledwithin a few months by SallyMcGill and Lisa Grant. It willbe available from SCEC.

Lisa B. GrantWoodward-Clyde Consultants

Year 1st quarter 2nd quarter 3rd quarter 4th quarterall 3.0+ all 3.0+ all 3.0+ all 3.0+

1990 3,483 56 2,627 45 2,225 27 2,403 31

1991 2,041 11 2,218 32 2,445 23 2,651 29

1992 3,618 40 10,288 744 25,500+ 801 10,700+ 166

1993 4,939 43 5,370 61 5,298 48 4,583 35

1994 10,915 417 5,967 43 5,400 48 5,031 40

1995 3,815 28 3,982 39

Southern California Seismic NetworkSouthern California Seismic NetworkSouthern California Seismic NetworkSouthern California Seismic NetworkSouthern California Seismic Network

Earthquake Statistics: Earthquake Statistics: Earthquake Statistics: Earthquake Statistics: Earthquake Statistics: 1 January - 1 July 19951 January - 1 July 19951 January - 1 July 19951 January - 1 July 19951 January - 1 July 1995

Seismicity reports areissued every Thursdaymorning by the SCSN andare available via the SCECData Center’s anonymousftp site, its World WideWeb (WWW) interface(http://scec.gps.caltech.edu),and the Usenetca.earthquakes.newsgroup.

Weekly reports consist of amap (e.g. postscript file950209.ps or gif format file950209.gif) and a commen-tary (950209.txt) at a levelintended for the public.

Totals listed below applyto the area within apolygon bounded by thefollowing latitude/longitude pairs: 35.0N,121.0W; 37.0N, 119.0W;37.0N, 115.0W; 32.5N,115.0W; and 32.5N,121.0W.

Kate Hutton

Northridge Earthquake,17 January 1994 - 30 June 1995Latitude 34.1 - 34.5 North,Longitude 118.3 - 118.85 West

All events 11,866 (446 more this quarter)3.0 - 3.9 3784.0 - 4.9 485.0 and up 10

Landers/Big Bear Earthquakes,23 April 1992 - 30 June 1995Latitude 33.8 - 35.33 North,Longitude 116.0 - 117.05 West

All events: 56,000+ (1,735 this quarter)3.0 - 3.9 1,5304.0 - 4.9 1625.0 and up 21

Map of southernCalifornia showingthe earthquakesrecorded during theweek of July 6-12,1995. Source:Caltech/USGSSeismic Network,Kate Hutton.



SCEC Participates in the City of Los Angeles

Earthquake Fair

The citizens and denizens of Los Angeles,thanks to the Earthquake Center, weretreated to a unique experience at the City ofLos Angeles-sponsored Earthquake Festivalheld 21-23 April in observation ofCalifornia’s official Earthquake AwarenessMonth. SCEC’s premier participation in thisannual event featured its visually excitingand fully interactive Great QuakeAwareness Game. Played on a colorfulgiant 400 square-foot game board, the gamechallenged players of all ages. A few of ourfavorite moments are captured here.

Curt Abdouch

Under Construction: SCEC World Wide Web Home Page

Earthquake Information ResourcesEarthquake Information ResourcesEarthquake Information ResourcesEarthquake Information ResourcesEarthquake Information Resources

New studies sponsored by the U.S. Department ofHousing and Urban Development are now available freeof charge via Internet at gopher huduser.aspensys.com 73.

"Assessment of Damage to Residential Buildings Causedby the Northridge Earthquake" presents findings of adamage survey of single-family detached houses andmultifamily low-rise and single-family attached develop-ments. Study results show that major structural damage toresidential buildings was unusual, although manymultifamily buildings that were built above an open-airparking garage were severely racked and some collapsed.

"Preparing for the 'Big One'--Saving Lives ThroughEarthquake Mitigation in Los Angeles, California" expandsthe scope of HUD's assessment to include schools, hospi-tals, utility "lifelines," roads, and dams. The reportdiscusses an issue now confronting policymakers--how toundertake and sustain mitigation measures that willeffectively minimize the human, physical, and economictoll of the next major earthquake.

These studies ($4 each) can also be requested by contacting:HUD USERP.O. Box 6091Rockville, MD 20849phone 1-800-245-2691

HUD's Office of Policy DevelopmentPublishes Damage Survey Findings

Reprints of Seismic Hazards in Southern California:"Probable Earthquakes, 1994 - 2024," published in the Apriledition of the Bulletin of the Seismological Society of America,is available through the SCEC Administrative Offices.Copies, which include color figures and maps, are $5 each.

Contact:SCEC Knowledge TransferUniversity of Southern CaliforniaMail Code 0742University ParkLos Angeles, CA 90089-0742phone 213/740-5843fax 213/740-0011e-mail: [email protected]

Seismic Hazards Report Now Available

Need to know the names andhome institutions of theSCEC scientists currentlystudying blind thrust faultsin the Los Angeles Basin?

Need quick access to theSCEC Scientists'Publications List, but can'tfind your copy of theSCEC newsletter?

Want to see a list of allSCEC institutions andlink to each of theirWWW home pages?

By summer's end, internetusers will be able to do all thisand much more, through thenew SCEC WWW Home Page.Thanks to the efforts of SCECsummer employee SrividhyaGopalan, many SCEC docu-ments (including past andcurrent issues of the quarterlynewsletter) are in the process ofHTML conversion andmounting on the new homepage.

Here is a sample list of whatyou'll see:

Home Page:

"What is SCEC?"--a summaryof the Center's history and

purpose, including adescription of the MasterModel concept."Formal Mission"--Missionstatement and list of WorkingGroups and Leaders, with linksto more detailed descriptionsof the research conducted byeach of the groups."Organization"--a classicorganizational chart whichshows, at a glance, thestructure of the Center."Research"--a layer accessiblethrough the home page and the"Mission" page, with detaileddescriptions of each WorkingGroup's research to date.

The page also features links to:

• SCEC Core Institutions• SCEC InfrastructureFacilities--such as the SCECData Center at Caltech; theSCEC GPS Centers at UCLAand Scripps OceanographicInstitute; and the PortableBroadband Instrument Centerat UCSB.

• SCEC Outreach Programs• SCEC Products--such as theearthquake hazard analysismap; the Quarterly Newsletter;and SCEC Publications List.• "Surfing the Net forEarthquake Data"

Jill Andrews

SCEC WWW URLhttp://www.usc.edu/dept/earth/quake/index.html


Earthquake Information ResourcesEarthquake Information ResourcesEarthquake Information ResourcesEarthquake Information ResourcesEarthquake Information Resources

...To Call or Write

For information about recent SouthernCalifornia earthquakes, call 1-800/286-7233, or 818/395-6977.

For information on earthquakes inNorthern California, call the U.S.Geological Survey in Menlo Park, 415/329-4011.

For information on earthquakes outside ofCalifornia, call the National EarthquakeInformation Center, 303/273-8516.

For phone numbers for emergency orservice agencies:

To reach the Federal EmergencyManagement Agency (FEMA), call: 1-800/525-0321.

For information on earthquakepreparedness, please consult your localyellow pages, or call the State Office ofEmergency Services at 1-800/286-7233.

If you have been emotionally affected byan earthquake and need counseling, callthe Los Angles County Department ofMental Health at 1-800/854-7771.

To offer or receive assistance from the RedCross, call 213/739-4543.

Strong motion recordings of the Northridge earthquake (17January 1994) at stations of the Los Angeles Strong MotionNetowrk are now available via anonymous ftp.

The main event was recorded by 65 stations. All the recordingsare on 70 mm film. A summary of uncorrected peak accelera-tions at these stations (a table and contours of equal accelera-tion) can be found in a paper by Trifunac et al., published inSoil Dynamics and Earthquake Engineering, Volume 13, No. 3,pp. 187-196, July 1994. The title of the paper is "A note onDistribution of Uncorrected Peak Ground Accelerations duringthe Northridge, California, Earthquake of 17 January 1994."

All 65 accelerograms have been digitized. A preliminaryrelease of Volume I data (uncorrected accelerations) is availableon the Internet. The data can be copied via anonymous ftp.The user needs to connect to host

usc.edu

and go to the directory

ftp/pub/todorovs/northridge

Major funding for processingcame from the USGS and NSF.Other funding was provided by US Navy Engineering FacilityCenter (Port Hueneme), Dames & Moore, City of Los AngelesDepartment of Water and Power, University of SouthernCalifornia, and USC Professor J. P. Bardet.

Volume II data (instrument and baseline corrected acceleration,velocity and displacement), and Volume III data (Fourierspectra and response spectra for five damping ratios) will beavailable at a later date.

Maria TodorovskaKAP 216A

Civil Engineering Dept.University of Southern California

Los Angeles, CA 90089-2531

Northridge Earthquake Data Release

The most recent source of information about faults in Califor-nia is the “Fault Activity Map of California." Copies may beobtained by mailing a check in the amount of $20, whichcovers the map and shipping, with your written request forMap #GDM-006, to:

California Division of Mines and GeologyPO Box 2980

Sacramento, CA 95812-2980

Earthquake Faults in Southern California Available On Line: The Seismic HazardsMap, Probable Earthquakes, 1994-2024

The Phase II map is now online through the World Wide Web.The URL is:

http://scec.gps.caltech.edu/PhaseII.html

We have added explanatory text for end users.

Earthquake EngineeringResource Materials

Technical Data on Earthquake Hazards

Natural Hazards Researchand Applications Information CenterCampus Box 482University of ColoradoBoulder, CO 80309-0482

The Center is a national clearinghouse for data relating toeconomic loss, social disruption, and human response associatedwith natural disasters. The Center seeks to strengthencommunication between researchers and individuals,organizations, and agencies responsible for reducing losses fromdisasters.

Phone 303/492-6818Fax 303/492-2151e-mail: [email protected]

Federal Emergency Management Agency (FEMA)500 C Street SWWashington, DC 20472

FEMA acts as the focal point for all levels of government todevelop national emergency management capability. Publicationlists are located on the FEMA World Wide Web site: http://www.fema.gov.

Phone 202/646-4600

Other Information Resources

Seismic Safety CommissionState of California1900 K Street #100Sacramento, CA 95814

The Commission concentrates on public policy, state legislation,and risk mitigation measures which lower earthquake risks to lifeand property in the State of California.

Phone 916/322-4917Fax 916-322-9476e-mail: [email protected]

Earthquake Engineering Research LibraryCalifornia Institute of TechnologyNational Information Service for EarthquakeEngineering (NISEE)

Earthquake Engineering Librarian Jim O'Donnell and LibraryAssistant Philip Roche can be reached by phone, fax, or e-mail.The library features strong-motion accelerogram data, technicalreports, a video and slide collection, conference proceedings andtechnical serials. The collection is available to the public on anin-house basis, and photocopying facilities are available. Formore information, contact O'Donnell or Roche at:


National Geophysical Data CenterNOAA E/GC1325 BroadwayBoulder, CO 80303

The Center collects, analyzes and disseminates technical data onearthquake hazards. Included in the list of products: AnEarthquake Data Base; an Earthquake Intensity File; a SignificantEarthquake Data Base; a Strong-Motion Archive.


U.S. Geological SurveyNational Earthquake Inormation CenterBox 25046Denver Federal CenterDenver, CO 80225

Products and services include an Earthquake Data Base System;an Earthquake Information Line (see page 24 of this newsletter);and an Online Information Program.

Phone 303/273-8500303/273-8450e-mail: [email protected]


SCEC Newsletter will accept calendar items for the October 1995 issue no later than September 15, 1995.

SCEC Activities CalendarSCEC Activities CalendarSCEC Activities CalendarSCEC Activities CalendarSCEC Activities Calendar

July 16-19 SCEC Knowledge Transfer Director Jill Andrews will be aparticipant on a panel entitled "Community Outreach" at the 20thAnnual Hazards Researchand Applications Workshop.

17-19 SCEC Annual Meeting, Ojai Valley Inn, Ojai, California

19 Robert S. Yeats, SCEC scientist and Professor, Departmenet ofGeosciences, Oregon State University, will present the 1995 Richard H.Jahns Distinguished Lecture in Engineering Geology, sponsored by theAssociation of Engineering Geologists and the Engineering GeologyDivision of the Geological Society of America. "Thin-Skin and Thick-SkinTectonics: The Earthquake Threat to the Ventura Region" will be thesubject of the presentation, to take place at 8 pm at the Coast GeologicalSociety in Ventura, CA.

27-October 5 SCEC representatives will present a session on KnowledgeTransfer at the XI Course of the International School on Solid EarthGeophysics Conference, "Active Faulting Studies for Seismic HazardAssessment," Erice, Sicily.

September

October 2-4 Association of Engineering Geologists Annual Symposium:Sponsored by SCEC Knowledge Transfer, session "Bringing theEarthquake Risk to the California State Legislature." Contact Eldon Gath,Leighton & Associates, phone 714/250-1421, fax 714/250-1114.

23-24 Association of Contingency Planners, Annual Symposium, Red LionHotel, Culver City, CA. See Page 16 for more information.

November 9-10 Insurance Industry Workshop, sponsored by SCEC KnowledgeTransfer. Final agenda and venue to be announced. Contact Jill Andrewsat SCEC (ph. 213/740-3459 or fax 213/740-0011) for more information.

13-15 NSF Science and Technology Center Administrators' and EducationCoordinators' Meeting, Washington, D.C.

16 SCEC Seminar, subject and venue to be announced.

SCEC has added a new telephone number. You can now reach the SCEC officesby calling either 213/740-5843 or 213/740-1560.

Zip Code

Write, Telephone, or fax this form to

Keiiti Aki, ChairmanUniversity of Southern California

Ralph ArchuletaUniversity of California,

Santa BarbaraRobert Clayton

California Institute of TechnologyJames Mori

United States Geological Survey

SCEC Board of Directors

Bernard Minster, Vice ChairmanScripps Institute of Oceanography

University of California, San DiegoDavid Jackson

University of California, Los AngelesLeonardo Seeber

Columbia University

Southern CaliforniaEarthquake Center

Administration

Science Director - Keiiti AkiExecutive Director - Thomas Henyey

Administration - John McRaneyEducation - Curt Abdouch

Engineering Applications - Geoffrey MartinKnowledge Transfer - Jill Andrews

T o S u b s c r i b eT o S u b s c r i b eT o S u b s c r i b et o t h e S C E C Q u a r t e r l y N e w s l e t t e r :t o t h e S C E C Q u a r t e r l y N e w s l e t t e r :t o t h e S C E C Q u a r t e r l y N e w s l e t t e r :

One year's subscription is $25.00. Please make payment by check, money order, orpurchase order, payable to "University of Southern California/SCEC." Please do notsend currency. Price includes postage within the U.S. Overseas airmail costs orspecial courier services will be billed. SCEC scientists and students and affiliatedagencies receive this newsletter free of charge.

Southern California Earthquake CenterUniversity of Southern CaliforniaUniversity ParkLos Angeles, CA 90089-0740Tel: 213/740-5843Fax: 213/740-0011

Name

Address

Telephone

Fax

E-mail address

Online subscriptions are now available! To activate your on-linesubscription, simply fill out the subscription form at:

http://www.usc.edu/dept/earth/quake/newsletter/subscribe.html

The first quarterly newsletter is free and is mounted for viewingto the public. All subsequent newsletters require subscriptionfee.

SS CC EE CC

SS CC EE CCSouthern California Earthquake CenterUniversity of Southern CaliforniaUniversity ParkLos Angeles, CA 90089-0742

ADDRESS CORRECTION REQUESTED

Non-Profit OrganizationU.S. Postage Paid

University ofSouthern California

SCEC Quarterly Newsletter

SCEC Quarterly Newsletter is published quarterly by the SouthernCalifornia Earthquake Center, University of Southern California,University Park, Los Angeles, CA 90089-0740, USA, telephone213/740-5843 or 213/740-1560, fax 213/740-0011, e-mail:[email protected]. Please send requests for subscriptionsand address changes to the attention of the editor.

Editor, Writer, and Production Artist: Jill Andrews

Science Director: Keiiti AkiExecutive Director: Thomas HenyeyAdministration Director: John McRaneyEngineering Director: Geoffrey MartinEducation Director: Curt AbdouchKnowledge Transfer Director: Jill Andrews

Subscription Form and Information: see page 27

Photographs and Figures:

J. Andrews (pp. 12, 13, 22)

M. Forrest (pp. 2, 4, 11, 15, 16, 17-19)

A. Martin (pp. 6, 8, 9)

D. P. Schwartz (pp. 1, 3)

Contributing Writers:

Curt Abdouch, SCEC

Keiiti Aki, USC/SCEC

James F. Dolan, USC/SCEC

Michael Forrest, USC

Lisa Grant, Woodward-Clyde Consultants

Kate Hutton, Caltech SCSN

Thomas Henyey, SCEC

Eric Lehmer, UCR/SCEC

Aaron Martin, UCSB/SCEC

David P. Schwartz, USGS

Mark Stirling, UNR

Mary Templeton, CSUF

Feature ArticlesSan Andreas Fault Trench Page 1What is SCEC? Page 2Master Model Progress Page 5Local Seismic Array Results Page 10SCEC Announces WWW Home Page Page 23

SCEC DepartmentsFrom the Center Directors Page 2Quarter Fault Page 4Infrastructure Centers News PBIC, UCSB Page 6 GIS Facility, UCR Page 7Recent Publications Page 10Activities Reports: SCEC Seminar Report Page 11 Field Trip: Faults of L.A. Page 12 SCEC GPS Workshop Page 16 Preliminary Findings, GIS Workshop Page 20 City of L.A. Earthquake Fair Page 22Visit with a SCEC Scientist Page 14Global Science Classroom News Undergraduate Workshop Page 17 SCEC Interns Field Trip Page 18SCSN Earthquake Statistics, 1995 Page 21Earthquake Information Resources Page 23Calendar Page 26

Inside this issue:

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Copy Editor

Rene Kirby, USC

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