Quarterly Newsletter Volume 5, Number 1 Southern California

2 Earthquake Center Exciting Initiative: EarthScope

3 Interview: John Anderson

9 Hough: Best-Laid Plans

10 Fault: Rose Canyon

16 Evaluating Liquefaction Hazard

18 Profiles: SCEC Interns

24 Benthien: A Funny Thing

26 Post-Earthquake Planning Seminar

29 Teachers Sacrifice for Science

S C EE C From the Center Directors

EarthScope—a New and Exciting Initiative By Tom Henyey

Center Director Science Director

The Earth Sciences Division proving our understanding of (EAR) at the National Science the earthquake process. Foundation (NSF) is working • How do faults and earth- densification of geodetic and with the scientific community Particularly relevant to earth- quakes interact with one seismic instrumentation along to orchestrate a new and poten- quake physics is the geodetic another in time and space? the northern San Andreas, and tially exciting scientific (strain) component of the initia- perhaps other faults, for in- initiative called EarthScope. tive, referred to as the Plate The PBO would measure defor- creased spatial resolution; 3) EarthScope would consist of Boundary Observatory (PBO). mation over a broad spectrum the linking of the major earth- large arrays of state-of-the-art The PBO is expected to consist of spatial and temporal scales quake-producing zones to of a mix of GPS instrumenta- and provide sufficient resolu- cover the seismogenic part of tion, strainmeters, and InSAR tion to constrain any transients the plate boundary; and 4) We would be in a posi- images that can be used to associated with short-wave- increasing the access to InSAR tion to detect precursory address such questions as: length phenomena such as data. strain transients that may earthquakes and magmatic prove practical for • How is deformation accom- activity. A close integration of While the main focus of the forecasting earthquakes modated within a plate PBO would be to gain a basic and volcanic eruptions. boundary zone? understanding of plate bound- The plate boundary ary processes, it also would • What controls the spatial observatory is expected provide information of practical seismic and geodetic instru- characteristics of plate to consist of a mix of value. In particular, we would mentation, much of it focused boundary deformation? GPS instrumentation, be in a position to detect pre- on active tectonics of the Pa- strainmeters, and InSAR cursory strain transients, should cific/Juan de Fuca-North • What controls temporal images. they occur, that may prove American plate boundary of the variations in a plate bound- practical for forecasting earth- western U.S. A deep earth ary? quakes and volcanic eruptions. observatory along the San seismometers, GPS, Let’s hope EarthScope becomes Andreas fault at Parkfield also • Are there deformation strainmeters, and InSAR is a reality—it’s our opportunity to would be part of EarthScope. transients that propagate necessary to provide uniform add significant new resources within the plate boundary strain-rate sensitivity at plate- to the entire earth sciences SCEC is one of several major zone? motion strain rates and across community. NSF-funded programs helping the temporal band from several EAR shepherd the initiative • What is the relationship Hertz to a decade. through the Foundation’s ad- between vertical and Editor’s Note: As this issue was ministrative structure. If funded horizontal tectonics? Thus, the establishment of a prepared, Bernard Minster was over the next several years, fully capable PBO will require announced as the new Acting these new facilities would be • How does plate motion progress in four areas: 1) a Science Director for SCEC. an important resource for a ultimately produce an more effective integration of Please see page 35 for the future earthquake center and earthquake? strainmeters and GPS for a truly administrative structure as of for achieving the goal of im- broadband observatory; 2) the August 1, 1999.

2 Southern California Earthquake Center Quarterly Newsletter Vol. 5, No. 1, 1999 Interview with SCEC Scientist

John Anderson Interviewed by Jill Andrews

John Anderson, director of the neered structure when the fault Seismological Laboratory at the mapped by geologists breaks.” University of Nevada at Reno So “synthetic” seismograms are and member of the SCEC board the goal. We want them to be of directors, is interviewed here so realistic that engineers can about his work in strong motion use them. But we also want California Earthquake Center, normally feel. So accelerograph seismology, especially in the them to be based on sound specifically, your work on the data is getting more interesting context of the SCEC mission. understanding of the physics of Phase III Report (need official to network seismology, and the the earthquake process so that name for this report). How distinction between strong SCEC: You and your group they will be reliable. would you define the term motion seismologists and others appear to be in a “transition “strong motion seismologist” to is getting blurred. Still, the zone” between basic research SCEC: How can this be someone who doesn’t have a original focus of strong motion and tangible products—in other achieved? background in geophysics? seismology is to understand words, you are trying to find ground motions that are strong results that are immediately JA: We have to bring in source JA: I’d define strong motion as enough to cause damage. useful. What have you found so physics, wave propagation, and earthquake motions that are That’s still true. far, and who will use the results scattering caused by the com- strong enough to feel. Strong of your work? plexity of the Earth. At the least, motion seismologists might also SCEC: How completely has the we have to take what others be recognized by one type of digital accelerograph replaced JA: First, I think it is not as far have learned and incorporate it instrument that is essential for the old analog instrument? Do from basic seismic research as into our models. On the other their research. They must have you still use both? accelerographs, which are distinguished from the instru- JA: The most common analog Nearly every task SCEC identified for southern ments used by most other strong motion accelerograph in California ought to be done in Nevada, in Utah, seismologists in that they stay the world, the Kinemetrics near New Madrid and every other seismic zone in on scale in even the strongest SMA-1, was discontinued many the U.S. shaking but can’t detect weak years ago, but there are still earthquakes that are easily large numbers of them out in observed using higher gain the field. The data they produce it may appear. I’m thinking of a hand, one can hope that our instruments. Twenty years ago, is very good data, but it’s less vision for strong motion seis- research; i.e., the constraints on before the digital revolution in convenient to use because they mology given in 1980 by Keiiti the physical processes needed instrumentation, the weakest record strong motions on film, Aki (SCEC director, 1991–1996) to successfully predict strong signals these instruments could which has to be retrieved and in an address when he was the motions, will lead to some record were just about at the then digitized. This is very time outgoing president of the Seis- increased understanding of the threshold of human detection. consuming. The advantage of mological Society of America. physics. Now, the digital accelerographs digital instruments is that the He said: “Our goal is to com- can record local earthquakes data are available immediately, pute seismic motion expected SCEC: Let’s focus on your work below magnitude 3, which is and the resolution is much at a specific site of an engi- as it relates to the Southern way below what a person can better. On analog, one can

Vol. 5, No. 1, 1999 Southern California Earthquake Center Quarterly Newsletter 3 Professional resolve differences in accelera- has either better or worse Highlights tion of maybe 1,000th of the funding than many other fields acceleration of gravity. With of seismology. For instance, John Anderson new digital instruments, there’s most of our regional seismic about a 100-fold improvement. networks are seriously under- Education funded. Research on data Ph.D., geophysics, Columbia University B. S., physics, Michigan State University SCEC: How does that affect collected by those networks is your work? also under-funded. Professional SCEC Board of Directors University of Nevada, Reno–Mackay School of Mines JA: With a really strong earth- SCEC: Why? Professor of Geophysics, Department of Geological Sciences quake, you’re well above the Seismological Laboratory Director “noise” level over a certain JA: There is the usual cliché Research Interests frequency band; with digital answer: that without more John Anderson’s research in strong motion seismology has taken him to instruments, you are well above frequent disasters, the public Mexico, Japan, Turkey—and yes, even exotic southern California. He’s the noise level for a wider and Congress tend to forget hosted visiting scholars from India, Iran, China, and Korea, and looks forward to traveling to those places. His research interests span all as- range of frequencies. So you about earthquake hazards, and pects of engineering seismology, including applications of geological have much more accurate data seismology drops to a lower and seismological information to estimate seismicity and seismic haz- for both lower and higher priority on the political agenda. ards; recording strong ground motions; understanding the physics of frequencies than with the old That may contribute to the near-source ground motions; and applications to engineering problems. problem, but I don’t think it is Selected Publications the complete answer. Another Anderson, J. G., and S. Hough, A model for the shape of the Fourier Major earthquakes occur amplitude spectrum of acceleration at high frequencies: Bull. Seism. Soc. factor may be an apparent Am. 74:1969-1994, 1984. rarely, and every one is weakness in our case for rel- either an opportunity or a Anderson, J. G., P. Bodin, J. Brune, J. Prince, S. Singh, R. Quaas, M. evance. The building code is Onate, and E. Mena, Strong ground motion and source mechanism of missed opportunity to the only place where most the Mexico earthquake of Sept. 19, 1985, Science 233:1043-1049, learn more. people have to spend money 1986. on seismic hazards. These Zeng, Y., J. G. Anderson, and G. Yu, A composite source model for codes give “cookbook” answers computing realistic synthetic strong ground motions, Geophysical Re- instruments. Also, the same to seismic design for most search Letters 21:725-728, 1994. instruments record smaller structures, and our engineers Zeng, Y., J. G. Anderson, and F. Su, Subevent rake and random scatter- earthquakes, which can be are probably correct in their ing effects in realistic strong ground motion simulation, Geophysical Research Letters 22:17-20, 1995. used as empirical Green’s assertion that most structures functions for some of our re- are designed well for life safety. Zeng, Y., and J. G. Anderson, A composite source model of the 1994 Northridge earthquake using genetic algorithms, Bull. Seism. Soc. Am. search. With that apparent weakness, 86:S71-S83, 1996. how should we convince the SCEC: Let’s shift back to the general public and Congress Anderson, J. G., and G. Yu, Predictability of strong motions from the Northridge, California, earthquake, Bull. Seism. Soc. Am. 86:S100- field of strong motion seismol- that understanding more about S114, 1996. ogy. According to your the earthquake hazard is essen- Anderson, J. G., Seismic energy and stress drop parameters for a com- colleague and coordinator of tial for making better decisions posite source model, Bull. Seism. Soc. Am. 87:85-96, 1997. the SCEC Phase III report (Ned on a daily basis, thus reducing Ni, S.-D., R. Siddharthan, and J. G. Anderson, Characteristics of nonlin- Field), logic dictates that strong the future risk? Of course, there ear response of deep saturated soil deposits, Bull. Seism. Soc. Am. motion seismology should be a are existing programs that 87:342-355, 1997. well-funded branch of seismol- demonstrate the relevance of Lee, Y., Y. Zeng, and J. G. Anderson, A simple strategy to examine the ogy. Is there enough support this kind of research—TriNet is sources of errors in attenuation relations, Bull. Seism. Soc. Am. 88:291- provided by government agen- one example. TriNet [Ed. note: 296, 1998. cies, or could there be more? the USGS-Caltech-California Su, Feng, J. G. Anderson, and Y. Zeng, Study of weak and strong ground Division of Mines & Geology motion including nonlinearity from the Northridge, California, earth- JA: More support could be consortium to upgrade quake sequence, Bull. Seism. Soc. Am. 88:1411-1425, 1998. used to accelerate both scien- California’s seismic networks to Anderson, J. G., and J. N. Brune, Probabilistic seismic hazard analysis tific discovery and the digital] gives immediate infor- without the ergodic assumption, Seismological Research Letters 70:19- 28, 1999. development of practical re- mation for emergency response sults. In this regard, I’m not so and to satisfy the broad curios- sure strong motion seismology ity about earthquakes; those are

4 Southern California Earthquake Center Quarterly Newsletter Vol. 5, No. 1, 1999 as the new probabilistic seismic empirical earthquake source hazard maps produced by the functions. Our synthetic More About the SCEC USGS and the California State Green’s functions include wave Phase III Report Department of Conservation’s propagation in an attenuating Division of Mines and Geology. Earth, and we’ve added in scattering calibrated from small Several years ago SCEC embarked on a multidisciplinary ef- SCEC: Can these uncertainties earthquakes. The composite fort to determine how and whether seismic hazard analysis be resolved over time? What source seems to have the right can be improved by accounting for site effects (the propensity can scientists do to reduce the amount of complexity, and the for certain sites to shake harder than others). large uncertainties? Or can we parameters can all be corre- As of 1997, the results of these studies had been combined learn to work with what we lated with macroscopic into an engineering-style report (called the SCEC Phase III Re- port), which was reviewed by an independent team of experts. have and concentrate on miti- variables like seismic moment They agreed that the report contained many important findings gation? and energy. We’ve tested it but that it needed some streamlining. against the observations for the After some delay it became apparent this would not happen JA: My opinion is that SCEC is major earthquakes in southern without a full-time editor. One now exists—Edward (Ned) Field— doing exactly what needs to be California, and it seems to and the report is well on its way to completion. done to reduce uncertainties. perform reasonably. The model Rather than producing a document primarily aimed at engi- We are conducting research has a random part to it, but neers, Phase III will be published as a collection of scientific that ultimately will benefit we’ve shown that the source of papers in a special issue of the Bulletin of the Seismological society, because in the long run Society of America (pending acceptance). Issues that were reducing the uncertainties will addressed in the earlier version relating to the characterization be more economical. The latest SCEC has given the of seismic sources (updating Phase II) and to computing syn- seismological community thetic seismograms have been omitted. The report will now focus SCEC RFP is a masterpiece. [Ed. exclusively on how, and whether, probabilistic seismic hazard note: every year the SCEC a transportable model for analysis (PSHA) in southern Californiacan be improved by ac- board of directors develops a attacking the scientific counting for site effects. research plan that is circulated and social issues associ- Field and colleagues made a diligent search for any character- to SCEC researchers as a re- ated with earthquakes. istics that systematically predispose a site to greater (or lower) quest for proposals, inviting levels of ground shaking. They found some significant attributes, them to submit a proposal such as surface geology and depth to bedrock in sedimentary describing what they would several earthquakes, including basins that indeed correlate with observed amplification fac- tors. They also tested which of several attenuation relations are like to do to help achieve that the Northridge earthquake, can most consistent with southern California data and with theoreti- plan in the coming year.] be described with a specific cal considerations where data are lacking. They are currently Nearly every task SCEC identi- realization of the model. We’re quantifying the influence of these factors on PSHA. fied for southern California still working on improving it. A preliminary conclusion is that except in some specific circum- ought to be done in Nevada, in And it is being used in some stances, only modest improvements can be made by accounting Utah, near New Madrid and applications in private industry. for site effects. However, even modest improvements may be every other seismic zone in the One of the latest phenomena significant in terms of the implied seismic hazard. U.S. Every task would make a that we’ve found necessary to significant contribution to include in the model is understanding the earthquake nonlinearity in the soil re- threat in those areas, also sponse. When we make a model that is successful for all strong selling points for the support for seismology would SCEC: Let’s get back to your the distant stations it signifi- general public. Another ex- be much better. group’s contributions. cantly overpredicts the ground ample is SCEC’s outreach motions at the closest sites. program, which is excellent. It SCEC: How do you resolve this JA: For the past few years, Then when we apply a more- does a great job of sharing our “apparent weakness” in the primarily with SCEC support, or-less standard correction to excitement about our scientific case for relevance? we’ve been developing what those nearby sites for expected discoveries. If we as a seismo- we call a “composite source nonlinear stress-strain relation- logical community did as well JA: First, I think there are really model” to predict strong mo- ship in the alluvium below in outreach in the rest of the large uncertainties in the inputs tions. The approach is entirely those sites, the predictions nation, maybe the national to even the newest code guide- synthetic. We don’t use empiri- come in much closer to the lines and/or requirements, such cal Green’s functions or observations.

Vol. 5, No. 1, 1999 Southern California Earthquake Center Quarterly Newsletter 5 SCEC: To improve seismic site conditions in some way the process is endlessly compli- JA: That’s a difficult question design and probabilistic seismic also. cated. Strong ground motions because “design professionals” hazard assessment, you and are extremely complicated time includes a wide range of activi- your colleagues conduct regres- The first step of the process series. Anyone who hopes to ties—an architect planning a sion analyses to develop includes making up an ad-hoc characterize them adequately one-story house, on one hand, empirical ground motion mod- form for the equation—some- with a few parameters is or, at the other extreme, struc- els, which predict ground thing that you hope will doomed to failure. The ground tural engineers who design motion characteristics as a capture the average trends. The motion prediction equations skyscrapers; the latter are function of magnitude and second step uses regression may be developed for a dozen people who are usually talking distance. Can you explain what analysis to estimate the un- or so characteristics of a suite to strong motion seismologists of seismograms. But that is not in the first place. They would enough. Also, every time an- be the people more likely to other earthquake happens you ask for seismograms to test their have to carry out a new regres- designs. sion, and every time you use the prediction equation you SCEC: Let’s talk about the have to worry about whether it progress of strong motion is appropriate for the region. seismology in relation to better That’s why the type of “ground engineering design on a world- motion prediction” that we are wide basis. Are researchers in mainly working on is synthetic your field making less rapid seismograms. progress than if there were more funds for the field? There is far more information in synthetic seismograms than in JA: The answer is yes. Major any prediction equation. If we earthquakes occur rarely, and An observed strong motion accelerogram compared to a synthetic one. can generate a reliable syn- every one is either an opportu- (Prepared by Y. Zeng, 1999, based on work in progress.) thetic seismogram, then the nity or a missed opportunity to engineer can determine any learn more. There are a lot of is involved with doing regres- known coefficients in these parameter he wants from the questions about the earthquake sion analyses, define in simple equations. This approach synthetic seismogram. We don’t source that will only be finally terms what an empirical ground generally predicts ground need to worry about the answered with strong-motion motion model is, and explain motions to within a multiplica- whether the prediction equa- observations. An example why prediction of ground tive factor of about two. In one tions that we used are correct. would be the question of how motion characteristics as a of our Phase III contributions, I Instead, we worry about long the San Andreas fault takes function of magnitude and examined the physics to try to whether the source model and to slip in a major earthquake. distance is important to design make some general statements the earth structure model that One thing we know is that professionals? about the expected characteris- tics of these prediction JA: There are several ways to equations, and we also evalu- Supporting more strong motion instruments at predict ground motions. The ated some of the existing major faults around the world is expensive, but we standard engineering approach equations for use in southern stand to learn the answers to some fundamental is with a ground motion predic- California. questions sooner. tion equation. This approach seeks to predict some ground I have to admit, though, that motion parameter, such as peak I’m not particularly enthusiastic we used are correct. Ultimately, strong motions are highly acceleration, as a function of about developing new ground this will be much simpler than variable over space, and the several variables, which have motion prediction equations. ground motion prediction motion field is seriously to include magnitude and The first problem with these is equations. undersampled. To get a descrip- distance. Generally these that there is little to be learned tion of the strong motion field equations add additional terms about the physics of earth- SCEC: What can scientists do to without spatial aliasing, we that seek to characterize the quakes or wave propagation in help design professionals incor- need many more strong motion the process. The second is that porate research results? instruments than there are at

6 Southern California Earthquake Center Quarterly Newsletter Vol. 5, No. 1, 1999 present. Yokohama is the only believe that there are major city in the world that is cur- earthquake occurrences (M 7.8- rently operating a strong 8 or greater) quite frequently, Glossary of Engineering motion network approaching a about once every 50 years or Seismology Terms sufficient density to thoroughly less. We installed 30 strong document the strong motion motion instruments on rock wavefield at the frequencies sites in the vicinity of Guerrero Source physics: how one side of the fault slips past the other, that affect structures. They have Gap. Shortly after we started and the physical principles that drive the slip 150 accelerographs in an area the project, the September 19, of 433 km2, or about one in- 1985, earthquake occurred Wave propagation: how the seismic waves get from the fault to wherever they are going. strument every 3 km2. Tokyo is (M 8.1). The records we got on working on an even denser the Pacific coast are still almost Scattering: an important part of wave propagation. Scattering network. Mexico City’s network unique due to their location means some of the energy goes off in different directions rather than traveling in a straight line. Think of baseball: a strong is also very good. Its density is directly above the fault in a centerfielder trying to throw a ball to home plate might be able much lower, but the dominant M 8+ earthquake. It turned out to throw it in a straight line all the way, but he might also throw motions are low frequency that the Guerrero data was it to shortstop, who throws it to third base, who throws it to waves, so you can get start to critical for understanding the home. It’s an indirect route, but the ball still gets there. Like- get a good picture of what is ground motions in Mexico City, wise, if there are obstacles at different locations in the Earth, the seismic waves might take an indirect route. Complexity happening. With the complex- which is 400 km from the fault. causes “packets” of energy to arrive at different times. ity of seismic waves in basins, The really interesting result we this empirical approach may be found was that Mexico City Empirical Green’s functions: recordings of waves from very small earthquakes, which are more abundant than large ones, that the best way to understand and experienced about the same can be used to predict strong ground motions. This is done by prepare for local variations in peak accelerations as the area “scaling up” the small seismograms. the motions. directly above the fault that moved, due to the type of soil Is it fundamental science? in Mexico City. An important Conceptually, if you have a lesson from this also is the good enough description of the value of international collabo- velocity model and a big ration. JA: There’s occasionally the all the difficulties in detail. You enough, fast enough computer, opportunity to get involved in a have to come up with your best maybe the spatial variation in I know that supporting more design project through an answer given the time con- the motions could be predicted. strong motion instruments at engineering consulting firm, but straints that are available. But I think that density of stations major faults around the world is I don’t make any effort to the interaction is very valuable. would be approaching a level expensive. The advantage is pursue those projects, so I don’t On those projects, you find out where a new challenge could that we stand to learn the do that very much. A significant what exactly are the problems be tackled, though, namely to answers to some of our funda- source of support for our group that need to be solved. It’s quite invert the complete observed mental questions sooner than has been from Pacific Gas and common to realize that their wavefield to derive the struc- we would if we wait for the Electric through PEER (Pacific problems are actually pointing ture of the basin. same type of earthquake in Earthquake Engineering Re- towards fundamental research California. That could reduce search Center). That is more questions. SCEC: You mentioned Mexico. uncertainties for design of like private industry than like Describe some of your research structures here; over time, the SCEC. We’ve also had support SCEC: For instance? there. greater economic benefit would from the grants programs of the far outweigh the cost of the National Science Foundation, JA: For instance, right now JA: I’ve been working in international experiment. the US Geological Survey, and we’re dealing with “kappa” at Mexico since 1980. Jim Brune the California Strong Motion Yucca Mountain. That’s a (UNR) and I installed a strong SCEC: Back to the question of Instrumentation Program. The parameter that Sue Hough motion network in Guerrero support. What other avenues of trade-offs question is easy. (USGS Pasadena) and I defined [Ed. note: the Guerrero support exist for groups such as Support from private industry is several years ago to describe Accelerograph Array is near yours (i.e., private industry) and very much more focused— the spectral shape of high Acapulco, which is above the what trade-offs may exist when driven by strict deadlines. You frequency accelerograms. subduction zone along the you conduct research with may not have much time to There are some fundamental Pacific coast]. In this zone, we industry support? think through and try to solve questions about its physics that

Vol. 5, No. 1, 1999 Southern California Earthquake Center Quarterly Newsletter 7 we’re being forced to deal with “ergodic,” “aleatory uncer- On average, our observations the contradiction would go as a result of the way we are tainty,” and “epistemic of ground motions vary about away. A big challenge that using it for the Yucca Mountain uncertainty.” But our results prediction equations within a remains is to figure out how project. We don’t understand potentially contribute to solve a range of about plus or minus a much of the total uncertainty why there is so much variability significant puzzle. The puzzle multiplicative factor of two. falls into each category. If the from one earthquake to the is that there are old, precari- This is a standard deviation of a great earthquakes on the San next. ously balanced rocks within probability distribution, so with Andreas ruptured in an identi- sight of the San Andreas fault. enough cases there are obser- cal way every time, all the SCEC: Can you explain this The SCEC Quarterly Newsletter, vations that vary by even more. uncertainty would be further? Why is this important That is predominantly a spatial epistemic. The ground motion to the Yucca Mountain project? variability of ground motions— at the site would be identical in typically our data are every earthquake. If it doesn’t JA: Yucca Mountain has been dominated by a few large knock down a precarious rock using synthetic seismograms, earthquakes that have given a the first time, then it never will among other techniques, to lot of observations at a lot of unless geological processes characterize what the ground different places. The basic keep making the rock more motions might be in the (un- PSHA takes that uncertainty in precarious. At some of the likely) event of an earthquake the predictions and treats it as if precarious rock sites, Jim Brune there. It’s not very seismically it is the variability over time. makes a convincing case that active and there’s not much That is what we call the “er- the geological processes are data to work with, so synthetic godic assumption.” In this very slow now. seismograms play a more model, if we could record significant role. One constraint ground motions at the same site SCEC: From your perspective as on the synthetic seismograms is from a dozen characteristic director of the Nevada Seismo- Fourier amplitude spectrum of the that they should have the same N85°E component of strong motion earthquakes on the San Andreas logical Laboratory, what is the value of kappa as observations acceleration recorded at Cucapah fault north of Los Angeles, there impact of SCEC? from small earthquakes. So it’s during the Mexicali Valley would be a dozen different earthquake of June 9, 1980 (M 6.2). not a comfortable situation Accelerograph was a digital ground motions, and they JA: SCEC has given the seismo- when kappa is more variable recorder that samples at a rate of would vary over a range from logical community a among small earthquakes than 200/sec. (A) Log-log axes. (B) one half of the mean prediction transportable model for attack- Linear-log axes, illustrating the you think it ought to be. definition of the parameter kappa to twice of the mean predic- ing the scientific and social (k). This figure is from the paper by tion, and even more. With this issues associated with earth- SCEC: A recent paper you Anderson and Hough (1984) that model, if you wait long enough quakes. We need to continue a first defined kappa. authored that was published in at any one place next to the center in California to study Seismological Research Letters San Andreas fault, you get earthquake physics. However, (January-February 1999) ad- Vol. 4, No. 1, featured one on really extreme accelerations. the rest of the country also dresses uncertainties associated the cover. This is probably why the PSHA needs research of the type that with using a catalog of re- predicts accelerations that SCEC carried out in southern corded earthquakes as a proxy The San Andreas fault is in the would topple precarious rocks. California. We should have a when calculating expected background, 15 km away. A solution had already been similar center for the Great ground motions for one particu- PSHA (Probabilistic Seismic formulated before we wrote Basin, one for the eastern U.S, lar site and one particular fault. Hazard Analysis), as that previ- that paper. The uncertainty and one for the parts of the Can you explain how the ous article pointed out, predicts should be divided into two country threatened by subduc- “ergodic assumption,” as this is that ground accelerations parts. Epistemic uncertainty tion zone earthquakes. These called, is used in hazard calcu- sufficient to topple those rocks covers what we don’t know four centers would each be lations, and whether the issue should have occurred many about the path and site effects. focused on a different tectonic of uncertainties associated with times in the lifetime of those Aleatory uncertainty covers style. This would be an ex- it have an important impact on rocks. That forced us to think randomness that comes in from tremely effective way to results? more carefully about the PSHA the differences in the source promote a greater interaction of process. We suggested that the from one San Andreas earth- earth scientists, scientific dis- JA: This is a challenge to ex- problem arises with how we quake to the next. We covery, and outreach— plain, since some readers may enter the ground motions and demonstrated that if most of the everything that SCEC does—in be baffled by terminology like their uncertainties into a PSHA. uncertainty is epistemic, then the rest of the country.

8 Southern California Earthquake Center Quarterly Newsletter Vol. 5, No. 1, 1999 Tales from the Front By Susan Hough

Best-Laid Plans

I don’t remember what my the trip, and Jerry was able to a major earthquake would the daily, computer-oriented long-term plans were when I break away from his fieldwork happen, and they’d be the only grind he left behind. took my dog for a walk on one at times to join them. Did they two people around to deal with rainy October night in New feel a lot of aftershocks? On the it. Not too many minutes later, The SCEC workshop was a York back in 1989, but I do crystalline terrain of the San Vegan found Ned in the com- success. Attendees left with a remember my short-term plan. I Bernardino Mountains, report- puter room and let him know sense of optimism regarding was going to get home, dry off, edly not (providing evidence that they’d gotten their earth- our ability to lay the ground- and watch a World Series game that there really is something to quake. Two days after that, Ned work to optimize our chances on television. The baseball this business of site response). of a successful earthquake game didn’t happen, of course; response the next time one is I spent a long night at Lamont USC geologist Jim Dolan identi- called for. One is left wonder- instead. A mere 24 hours after fied Landers as having been a ing, though—is “next time” 10 that, I was eating a late dinner singularly ill-timed event in his years, or 10 minutes away? 24 at a Thai restaurant in Berkeley, life. He had carefully planned hours from now, are you going feeling like I must’ve somehow to take that Sunday off, his first to be at the appointment on wandered into a Star Trek day away from work in nearly your calendar, or some place movie and been whisked away two months. He’d even bought was in the Coachella Valley else? It’s like the Microsoft by the transporter beam. the early edition of the Sunday with fellow Lamont researchers slogan with a twist—not New York Times, in preparation Paul Friberg and Noel Barstow. “Where do you want to go A recent SCEC-sponsored for his day of leisure. At 10 They spent a week in the field, today,” but “Where are you workshop on earthquake re- o’clock the next morning, chasing basin edge effects and going to be tomorrow?” sponse seemed like an instead of sitting at his kitchen hoping their unreinforced appropriate occasion to pester table with the paper and a cup masonry hotel wouldn’t col- And if, underneath it all, we a few of my colleagues for their of coffee, Jim was in the lapse if the earth had yet didn’t love it at least a little, we stories. How had an earthquake Mojave Desert making his first another major temblor up its wouldn’t be in the earthquake- changed their plans and lives in reconnaisance of the surface sleeve. chasing business in the first recent years? Oddly, the first rupture. Did he ever get back to place. three people I asked all had the newspaper? Nope. Another Lamont scientist, Nano stories about the same earth- Seeber (who was not at the quake. The Landers earthquake was earthquake response workshop) also memorable for USC seis- recalled the Landers earthquake CDMG geologist Jerry Treiman mologist Ned Field, who, in in a different light. Although his first identified the M 7.2 1992 1992, was at Lamont. Ned prior plans were also scrubbed Landers earthquake as having reports having driven into the for a Monday morning trip to Interested in sharing a field- thrown a monkey wrench into lab early that day with fellow southern California, he recalled work story of your own? his plans for a family camping graduate student Vegan his impromptu fieldwork ad- [email protected] WWW-SOCAL.WR.USGS.GOV/HOUGH/ trip to, of all places, Big Bear. Aharonian. On their way in, venture as having been more His family did eventually make Ned joked that, with their luck, enjoyable and productive than

Vol. 5, No. 1, 1999 Southern California Earthquake Center Quarterly Newsletter 9 Featured Fault

Holocene Activity of the Rose Canyon Fault Zone By Scott C. Lindvall and Thomas K. Rockwell

The northwest striking Rose Although motion on the Rose This article presents informa- Canyon fault zone, which Canyon fault zone is generally tion from a three-dimensional bisects the city of San Diego, considered to be right-lateral paleoseismic trenching study

comprises a complex set of strike-slip (Kennedy, 1975), and other investigations and All figures: Lindvall and Rockwell anastomosing and en echelon individual strands within the summarizes our current under- Figure 1. Generalized map showing fault strands that include the fault zone display various standing of the Holocene major strands of the Rose Canyon fault zone and major geographic Rose Canyon, Mount Soledad, combinations of dip slip and behavior of the Rose Canyon features of the San Diego area. strike slip. The variable sense of fault zone. Individual faults within the zone dip-slip motion along this fault are the Country Club (CC), Mount Soledad (MS), Rose Canyon (RC), The dip-slip motion along has locally resulted in the uplift Rose Creek Study Site Mission Bay (MB), Old Town (OT), this fault has provided of Mount Soledad, the depres- Based on our tectonic geomor- Spanish Bight (SB), Coronado (C), San Diego with much of sion of San Diego Bay, and phic analysis, we selected a site and Silver Strand (SS). Faults are other physiographic features where the southeastern con- dashed where approximately its aesthetic beauty. located, dotted where concealed. that provide San Diego with tinuation of the Mount Soledad much of its aesthetic beauty. fault crosses the lowest terrace mine the style and width of Country Club, Mission Bay, Old of Rose Creek and formed a faulting and the type of sedi- Town, Spanish Bight, In 1989, two-dimensional low, east-facing scarp. The ment at the Rose Creek site Coronado, and Silver Strand trenching of the fault on the Rose Creek site, which was (Figure 3). The 22-m-long faults, in addition to many lowest terrace of Rose Creek trench exposed a 1.5 to 2.0-m- other secondary faults (Figure demonstrated that the fault thick section of artificial fill 1) (Kennedy, 1975; Kennedy displaces Holocene deposits The most recent large immediately below the paved and Welday, 1980). Offshore and showed that considerable surface rupture on the parking lot surface. Underlying mapping of faults in the South- strike slip was required to Rose Canyon fault the fill we exposed a section of ern California Borderland using explain stratigraphic mis- occurred during the past faulted clayey to silty sand on seismic stratigraphic techniques matches across individual few hundred years. which the surficial soils were (Legg, 1985; Legg and Kennedy, strands of the fault (Lindvall et partially intact. The fill was 1991; Fischer and Mills, 1991) al., 1990; Rockwell and emplaced in 1960 without has shown that the Rose Can- Lindvall, 1990). Subsequent graded in 1960 and is now disturbing the scarp or the yon fault zone extends three-dimensional trenching at occupied by an asphalt-cov- organic-rich A horizon north- northwest and joins the New- the Rose Creek site was able to ered parking lot of the San east of the fault (Figures 3 and port-Inglewood fault zone determine a slip rate and recog- Diego Gas & Electric Beach 4). However, southwest of the (Figure 2). The continuity of nize at least three Cities Operating Center, is one fault, grading removed much of faulting along this zone led paleo-earthquakes (Lindvall of the few accessible locations the A and Bt soil horizons. Fischer and Mills (1991) to and Rockwell, 1995). More in this urban environment Consequently, the original conclude that the Newport- recent studies have better where young, surficial sedi- ground surface, including the Inglewood and Rose Canyon constrained the timing of the ments were deposited across fault scarp, was effectively faults represent a single struc- most recent surface-rupturing the fault. buried and preserved or slightly tural element. earthquake (Rockwell and modified from that seen in the Murbach, 1998). In 1989 we excavated a single 1941 air photos. The fault was trench across the fault to deter- expressed in the trench expo-

10 Southern California Earthquake Center Quarterly Newsletter Vol. 5, No. 1, 1999 Initially, we excavated two corner of the site was graded in fault-parallel trenches that 1960. Therefore we had to straddle the fault (Figure 6) expose the channel in hand- immediately northwest of dug excavations across the fault trench T-1. These trenches zone beginning with trench T-2. were used to establish the site’s stratigraphy and to identify After logging trenches T-2 and fluvial features or sedimentary T-3, we excavated the artificial structures that could be used as fill at the site down to the top of Figure 2. Regional map showing major northwest-striking dextral-slip fault piercing points for quantifying the natural deposits in order to zones including the Newport-Inglewood (N-I)–Rose Canyon (RC) fault zone the amount of horizontal offset. trace the gravel channel to and that extends from San Diego to Los Angeles. Other faults are Sierra Madre (SMa), Whittier, (W), Elsinore (E), Palos Verdes (PV), THUMS-Huntington across the several strands of the Beach (T), Coronado Bank (CB), Descanso (D), Vallecitos (V), San Miguel In the 20-m-long trench T-2 fault. This resulted in a ~12 x (SM), Agua Blanca (AB), and Bahia Soledad (BS) faults. Labeled cities are (Figure 4), we found only one 18 m rectangular excavation Los Angeles (LA), San Diego (SD), and Ensenada (E). The source zone of the 1933 Long Beach earthquake is denoted by the hatched pattern, and the such feature, a gravel-filled that was 2-2.5 m deep with 1:1 dark shaded area offshore is Lausson Knoll (LK). Numbers refer to fault slip channel oriented normal to the slopes along the sides (Figure rates in millimeters per year. fault. The channel’s cross 7). From the floor of the pit, we section was exposed in both first excavated a short trench (T- sure as a flower-type structure horizons suggest that the most the northeast and southwest 4) across the fault to re-expose with several strands splaying recent earthquake likely oc- walls of the trench and was the the fault zone (Figure 6). We outward toward the surface. curred only a few hundred only gravelly channel deposit also re-excavated part of trench The individual fault strands years ago. in trenches T-1, T-2, or T-3. The T-2 (trench T-2A) to re-expose offset Holocene strata across a coarse-grained channel fill was the channel. A series of con- zone about 2 m wide. Some necting trenches were then strands crosscut others and excavated by hand to expose exhibit a complex micromor- The evidence suggests the last large surface rupture the channel to and across phology, suggestive of multiple may have involved the entire onshore portion of the different strands of the fault slip events. Nearly all fault (trenches T-5 to T-11), leaving fault zone. strands in the trench wall the channel preserved in intact exhibit an apparent west-side- blocks of sediment (Figures 6 up component of slip, which is Three-Dimensional Trenching distinctive amidst the relatively and 7). consistent with the east-facing Two-dimensional fault expo- fine-grained, weakly stratified, scarp seen in the 1941 photo- sures on a trench wall oriented silty to clayey sand deposits Stratigraphy graphs. The most recently perpendicular to the fault that characterize most of the The faulted sediments underly- active fault strands completely cannot resolve horizontal slip. exposures. The gravel channel ing the artificial fill consist offset the A, E, and Bt soil Previous studies of strike-slip was not present in trench T-3 predominantly of a sequence of horizons that marked the natu- faults (Sharp, 1981; Sieh, 1984; west of the fault zone, because clayey to silty sand deposits ral ground surface prior to Rockwell et al., 1986) have the section containing the that are locally weakly to grading and development in demonstrated the effectiveness gravel had been eroded or moderately stratified (unit C). 1960 (Figure 3). of three-dimensional trenching stripped when the northwest Also within unit C are several in resolving both horizontal Radiocarbon dating of detrital and vertical deformation, and charcoal samples revealed that we employed these methods at the stratigraphic section ex- the Rose Creek site. Based on posed in the trench was early to the results of our first trench (T- middle Holocene in age. This 1), we reoccupied this site with initial phase of trenching at the the intent of exposing the fault Rose Creek site demonstrated zone in three dimensions and Figure 3. Generalized log of trench T-1. Note the upward flowering that the Rose Canyon fault zone resolving the slip by mapping structure, mismatch of some stratigraphic units, and location of 14C samples (solid circles). Mapped units are: A, modern A soil horizon; B , B (argillic) was Holocene active. In addi- displaced fluvial features. t t soil horizon; C, stratified overbank alluvium; D, gravelly colluvium. Much tion, the sharp, distinct contacts of the A and Bt horizons have been stripped from the southwest side of the of the faults and surficial soil fault.

Vol. 5, No. 1, 1999 Southern California Earthquake Center Quarterly Newsletter 11 small lenses and sheets of fine, generally those that directly or during grading of the site in C2 this date also represents the moderately to well-sorted sand overlie the buried A horizons 1960. maximum age of the channel. and millimeter- to centimeter- and have had the least post- The actual age of unit C2 and thick layers of clay that depositional disturbance. The channel contains coarse the channel, however, is prob- generally extend laterally for as sandy gravel to gravelly sand in ably not significantly younger much as several meters. These Unit D is a gravelly silty clay the thalweg. These coarse than 8.1 kyr. stratified sediments overlie capped by a buried A horizon. deposits fine upward into, and massively bedded, gravelly silty This distinct unit is consider- in some places become indis- Determination of Slip and Slip clay deposits (unit D) that were ably darker, more massive, and tinguishable with, the overlying Rate exposed at the base of most of contains more clay than unit C. fine-grained overbank deposits. The amount of slip was deter- our trenches west of the fault. Furthermore, clasts ranging The sandy gravel at the base of mined by excavating the from pebbles to large cobbles the channel is 30-50 cm wide distinctive gravel-filled channel are common throughout this and 10-25 cm deep. The into and across the several The most recent event on unit. In trench T-8, several subangular to rounded clasts strands of the fault zone. The the Rose Canyon fault cobbles were grouped together were generally smaller than 5 position of the channel, indi- near the top of unit D and cm in this linear deposit that vidual fault strands, and each zone was likely on the 1 order of M 7. were associated with cultural flowed east to west across the trench wall was accurately artifacts. Based on the sorting, Rose Creek terrace. mapped using a surveying color, and massive character of instrument (Figure 6). Based on Except where deformed within unit D, we interpret this to be Five samples of detrital char- this map, we reconstructed the the fault zone, the stratigraphy primarily a colluvial or debris- coal from units C2, C3, C4, and channel such that adjacent is virtually horizontal through- flow deposit. out our trench exposures (Figures 3 and 4). The modern soil, with a dark, Dating of shells from fissures filled by an overlying organic-rich A (topsoil) horizon, faulted Indian midden deposit constrains the timing of The sediments comprising unit a discontinuous E (albic) hori- the latest rupture to after A.D.1523. C (Figures 3 and 4) are inter- zon, and a weakly to preted to be fluvial overbank moderately developed Bt sediments from Rose Creek (argillic) horizon, is developed D1 were dated by accelerator channel pieces were realigned because they are fine grained in the upper 60-80 cm of the mass spectrometry techniques (Figure 8). We backslipped the and thinly bedded, maintain section below the artificial fill. and yielded dendrochronologi- westernmost strand to the fairly uniform thickness, and The argillic horizon indicates cally calibrated ages ranging location where the stratigraphic are laterally continuous over that this soil was exposed at the from 8.1 to 9.4 kyr. The maxi- unit containing the channel several meters. Three weak surface substantially longer mum age of unit C2 is best was cut out during the grading buried soil A horizons within than at any of the buried A constrained by the youngest of 1960; because the channel unit C allow for its division into horizons. date from the underlying unit may have been present even four subunits, C1 through C4 C3, or about 8.1 kyr. Because farther to the northwest, the (Figure 4). Not all buried A Gravel-Filled Channel the channel is incised into unit amount of slip in the recon- horizons were recognized in Trench T-2 exposed a single every exposure, but the lower gravel-filled channel trending two are commonly preserved nearly perpendicular to the and were the most useful for fault that we used as the pierc- correlating between exposures ing line. The channel is and across faults. These buried stratigraphically part of unit C2 soils, which represent short in all exposures east of the fault hiatuses in deposition, are (Figure 4). Within the fault bioturbated, have a darker zone, the channel fills the base color than the surrounding of a narrow rill or gully that Figure 4. Log of southeastern part of southwest wall of fault-parallel trench T-2 showing flat-lying stratigraphy of the site and buried channel that was sediments, and obliterate strati- incised through unit C2 and into used as a piercing line. Units A, E, and Bt represent the topsoil, albic, and fication within the overbank unit C3. West of the argillic soil horizons that formed in silty to clayey sands of unit C. Unit C deposits. The best preserved westernmost fault strand, the was subdivided into four subunits (C1-C4). In this exposure, units C1 and C2 and most laterally continuous channel was removed prior to are undifferentiated. The subunits are separated by weak buried A horizons (short vertical wavy lines). Minor discontinuous lenses of sand (stipple) and stringers of sand and clay are clay (solid) are present throughout unit C.

12 Southern California Earthquake Center Quarterly Newsletter Vol. 5, No. 1, 1999 yr, with a best estimate of about thin to the west across this 1.5 mm/yr. The lower bound of scarp (Figure 5) indicating that 1.1 mm/yr is determined by our scarp formation occurred soon

trenching results, whereas the after the deposition of unit C3. upper bound of 2 mm/yr is Therefore the event that pro- estimated from a comparison of duced the scarp must have the geomorphology associated occurred soon after about 8.1 with the three principal strands kyr, the maximum age of unit

of the Rose Canyon fault zone. C3. The minimum of 8.7 m of Based on this comparison, it slip on the channel occurred appears likely that the Mount after this ~8.1 kyr event. Soledad strand carries the majority of the slip. A second event is indicated by a group of fault splays that Figure 5. Detailed map of the northwest wall of trench T-4 showing the Timing of Past Events displace unit C but do not primary structural elements and stratigraphic units. Unit C was subdivided 1 From the trench exposures, we displace the base of the B soil on the basis of weakly developed buried A horizons (shown as short t vertical wavy lines). Unit C contains thin beds and stringers of clay (solid), have evidence for at least three horizon (Figure 5). The time of silt (open), and sand (stippled). Evidence of bioturbation is shown by the events since about 8.1 kyr. The this event is unconstrained, but numerous krotovina (k). Note that the northeastern strands displace the A, earliest event is suggested by a there must have been sufficient E, and Bt soil horizons, which is the result of the most recent surface rupture, whereas the southwestern strands could not be traced to the top low scarp into which the time for soil development to of unit C1. gravel-filled channel incised. obliterate the fault traces in the East of the fault, the channel is soil. struction is a minimum value. minimum of 8.7 m of brittle within unit C2 (Figure 4). As the This reconstruction results in a slip, assuming no rotational channel crosses the fault zone The most recent event ruptured minimum of 8.7 m of right- deformation, and a maximum to the west, it incises into the ground surface and abruptly lateral strike-slip that postdates age of the channel of 8.1 kya. progressively older and deeper displaced all soil horizons on deposition of the gravel chan- This yields a minimum early strata so that the channel cuts the eastern strands of the fault nel. Vertical displacement of Holocene to present slip rate of into units C3 and the top of C4. zone in trenches T-1 and T-4 the channel across all but the 1.1 mm/yr. This rate is a mini- This indicates the presence of a (Figures 3 and 5). The absence mum from the perspective that scarp that formed between of significant bioturbation

(1) the slip determination is a deposition of unit C3 and the where the Bt horizon is juxta- We suggest the overall minimum value, (2) the age of formation of the channel. posed over the A horizon

slip rate is between 1.1 the piercing channel is a maxi- Furthermore, units C1 and C2 indicates that this event is very and 2 mm/yr. mum, and (3) other strands of the Rose Canyon fault zone may also be active. If the chan- westernmost strand was consis- nel is as much as 2 kyr younger tently west-side-up and totaled than the underlying dated 0.7 m. Although no piercing strata, then the slip rate is about points were available to mea- 1.5 mm/yr. If the change in sure the vertical slip across the channel trend through the fault westernmost strand, the 11-cm zone is the result of horizontal vertical separation of the top of drag, the lateral displacement is Unit D in trench T-9 implies at least 10 m, which increases that this fault produced only the slip rate to nearly 1.7 mm/ minor vertical slip. We estimate yr. a horizontal to vertical slip ratio of about 10:1 for the Mount Based on the above uncertain- Figure 6. Plan view map of trenches excavated to determine displacement Soledad fault (zone) at the Rose ties and allowing for the of the buried channel across strands of the fault. Channel is shown by Creek site. probability of some slip on stipple pattern. Faults are heavy lines, dashed where approximately other strands of the fault zone, located, queried where uncertain, and are shown at the stratigraphic level of the channel. Trenches shown with a dashed line were excavated from To establish a conservative we suggest that the overall slip the parking lot surface, all others excavated by hand from the pit floor. minimum slip rate, we use the rate is between 1.1 and 2 mm/ Portions of trench margins shown in bold indicate location of other figures.

Vol. 5, No. 1, 1999 Southern California Earthquake Center Quarterly Newsletter 13 Rockwell and Murbach (1998) It is possible, however, that demonstrated that the most these data could represent recent rupture in the La Jolla different earthquake ruptures area is consistent with the that are closely separated in timing of the latest earthquake time and space, rather than a on portions of the fault zone single event. that traverse the Mission Bay and downtown areas. Dating of The evidence for a near-histori- shells from fissures filled by an cal event at all three sites overlying faulted Indian suggests that the last large midden deposit constrains the surface rupture may have timing of the latest rupture to involved the entire onshore post-A.D.1523 Using the cali- portion of the fault zone. Slip in brated lower bound of A.D. this most recent event has been 1523 and an upper one of estimated at both the Rose Figure 7. Southward view of hand-excavated trenches dug into base of the large rectangular excavation, which approximately coincides with the base A.D.1769 yields a best estimate Creek site and in La Jolla near of artificial fill. Faults strike from upper left to lower right corner of of A.D. 1650 ± 125 for the age the coast. Based on re-evalua- photograph. Note cars in upper left corner for scale. of this event (Rockwell and tion of the three-dimensional Murbach, 1998). Because this data from Lindvall and young, probably less than horizons (Figures 3 and 5) date is indistinguishable from Rockwell (1995), it appears that several hundred years. This imply that very little time has the dates obtained from the the most recent event produced interpretation is supported by elapsed since the latest event. downtown study (Woodward- ~3 m of slip on the eastern fault other studies, which document The absence of significant Clyde Consultants, 1994), it is strands at the Rose Creek site the latest earthquake as occur- bioturbation where the Bt plausible, if not likely, that they (Rockwell and Murbach, 1998). ring on the order of ~300 years horizon is juxtaposed over the represent the same earthquake. This is consistent with a mini- ago, as discussed further below. A horizon indicates that this event is very young, probably A minimum of three events in occurring less than 500 years the last 8.1 kyr implies a maxi- ago (Lindvall and Rockwell, mum recurrence interval on the 1995). order of 4,000 years. This also requires that the last two events This estimate agrees with the produced an average of more results of trenching studies in than 4 m of slip per event. The the downtown San Diego area average recurrence interval that indicate a surface-ruptur- could be substantially less than ing event occurred on strands the maximum interval of 4,000 of the Rose Canyon fault zone years. These data indicate that post-A.D.1420 The timing of the recurrence interval for large this event is based on radiocar- surface-rupturing earthquakes is bon ages of detrital charcoal in on the order of a few thousand fissure fillings from the Sports years. Arena site (Woodward-Clyde Consultants, 1994). The lack of Most Recent Event historical accounts of large Multiple studies indicate that earthquakes in the San Diego the most recent large surface area constrains the timing of rupture on the Rose Canyon this event between A.D. 1420 fault occurred during the past and 1769, the year the Spanish few hundred years. Near Mis- established the first mission in sion Bay at the Rose Creek site, San Diego. Figure 8. Generalized map and reconstruction of the faulted channel. The the abrupt, distinct faulted reconstruction provides a minimum value of lateral offset because the contacts within the surficial soil stratigraphic units containing the channel are missing west of the westernmost fault strand northwest of the shaded triangle.

14 Southern California Earthquake Center Quarterly Newsletter Vol. 5, No. 1, 1999 Museum Features mum displacement of >1 m Lindvall, S. C., T. K. Rockwell, and C. E. Lindvall, The seismic hazard Work of SCEC Scientist estimated at the La Jolla site of San Diego revised: New SCEC’s Thomas Rockwell (San Diego State University) was inter- (Rockwell and Murbach, 1998), evidence for magnitude 6+ viewed about his research on the paleoseismicity of the San Andreas which is located over 5 km to Holocene earthquakes on the Rose Canyon fault zone, Proc. fault by the American Museum of Natural History for the Hall of the north. Based on the amount Fourth U.S. Natl. Conf. Earth- Planet Earth, a new permanent exhibition devoted to earth sciences. of slip and a minimum rupture quake Eng., 11, 679-688, 1990. A portion of that filmed interview will be shown in the new hall. length of at least the onshore portion of the fault zone, the Rockwell, T. K., and S. C. Lindvall, Holocene activity of the Rose most recent event that occurred Canyon fault in San Diego, NISEE Releases Software on Rose Canyon fault zone was California, based on trench likely on the order of ~M 7. exposures and tectonic geomor- on CD-ROM phology: GSA, Abstracts with Programs, v. 22, p. 78, 1990. "NISEE Software Library CD-ROM," a comprehensive collection of References 112 engineering research software programs, is available from the Fischer, P. J., and G. I. Mills, The Rockwell, T. K., and M. Murbach, National Information Service for Earthquake Engineering (NISEE), offshore Newport-Inglewood-Rose Holocene earthquake history of University of California, Berkeley. Applications range from strong Canyon fault zone, California: the Rose Canyon fault zone, motion data processing programs to geotechnical and structural Structure, segmentation, and NEHRP Final Technical Report, analysis tools; user documentation for all programs on the CD-ROM tectonics, in Environmental Perils, USGS Grant No. 1434-95-G- San Diego Region, edited by P. L. 2613, p. 36, 1998. is available through NISEE. Cost is $139, including shipping in the Abbott and W. J. Elliot, pp. 17-36, U.S. Order from NISEE, University of California, Berkeley, PEER San Diego Assoc. of Geol. for the Rockwell, T. K., R. S. McElwain, D. Building 451 RFS, 1301 South 46th Street, Richmond, CA 94804- GSA meeting, San Diego, E. Millman, and D. L. Lamar, 4698; (510) 231-9403; fax: (510) 231-9461; California, 1991. Recurrent late Holocene faulting on the Glen Ivy North strand of [email protected]. Web site: WWW.EERC.BERKELEY.EDU. Kennedy, M. P., Geology of the the Elsinore fault at Glen Ivy western San Diego metropolitan March, in “Neotectonics and area, California; Del Mar, La Jolla Faulting in Southern California,” and Point Loma quadrangles in Geol. Soc. Am. Guidebook, 167- Strong Motion Consortium “Geology of the San Diego 175, 1986. Metropolitan Area, California,” Successfully Launched Bull. Calif. Div. Mines Geol. 200, 9-39, 1975. Sharp, R. V., Variable rates of late The Consortium of Organizations for Strong-Motion Observation Quaternary strike-slip on the San Systems has submitted its bylaws as a public-interest nonprofit Jacinto fault zone, southern corporation for earthquake safety to the Secretary of State in Sacra- Kennedy, M. P., and E. E. Welday, California, J. Geophys. Res., 86, mento and now has an office and staff in the PEER Building in Recency and character of faulting 1754-1762, 1981. offshore metropolitan San Diego, Richmond, California (COSMOS, c/o PEER, 1301 S. 46th Street, California, Map Sheet 40, Calif. Richmond, CA 94804-4698; Tel: (510) 231-9436; fax: (510) 231- Div. Mines and Geol., Sacra- Sieh, K. E., Lateral offsets and 9471; email: [email protected]). The launch of this umbrella mento, 1980. revised dates of large prehistoric consortium has met with widespread interest among earthquake earthquakes at Pallet Creek, engineers, emergency planners, and seismologists. COSMOS is now Legg, M. R., Geologic structure and southern California, J. Geophys. tectonics of the inner continental Res., 89, 7641-7670, 1984. in a position to influence management of the new National Seismic borderland offshore northern Baja System recently approved by Congress. A subcommittee of COSMOS California, Mexico, Ph.D. has already produced recommended standards for a national reposi- dissertation, Univ. of Calif., Santa Woodward-Clyde Consultants, tory of strong motion records. Barbara, 1985. Fault hazard investigation for the entertainment and sports center, Legg, M. R., and M. P. Kennedy, San Diego, California, unpub- A regular board and working committees will be elected at a general Oblique divergence and lished consulting report prepared meeting of all interested persons and eligible members on Septem- convergence in the California for Centre City Development ber 16 following the SMIP 99 annual meeting near either Oakland or continental borderland, in Corporation, p.19, 1994 San Francisco airport. At that meeting membership fees and COS- Environmental Perils, San Diego Region, edited by P. L. Abbott and MOS operating policies will be discussed. A descriptive brochure is W. J. Elliot, pp. 1-16, San Diego available on request from the above address. Assoc. of Geol. for the GSA Mtg., San Diego, California, 1991. Geologist Placement Lindvall, S. C., and T. K. Rockwell, Holocene activity of the Rose Service Canyon fault zone, San Diego, California, J. Geophys. Res., v. Onsite Environmental Staffing, a placement firm for professionals in 100, p. 24,121-24,132, 1995. the environmental and engineering fields, has positions available ranging from entry level to registered geologists with leading main- stream geology firms in southern California. Email or fax resumes, or call to set up an interview. Erik Applebee: (714) 245-4725; (800) 338-4199; fax (714) 954-0726; [email protected]

Vol. 5, No. 1, 1999 Southern California Earthquake Center Quarterly Newsletter 15 Using the New Hazard Maps

State Guide Tells How to Evaluate Liquefaction Dangers By Mark Benthien

A new document to help engi- ground water lose strength neers, geologists, and building because of strong ground officials evaluate and take shaking. This liquefaction protective measures against could result in settling and liquefaction hazards in south- sliding, leading to damage to ern California is now available. buildings on such soils. The new report asserts that lique- Recommended Procedures for faction is sufficiently Implementation of DMG Spe- understood now so that soil cial Publication behavior during earthquakes 117—Guidelines for Analyzing can be predicted. Therefore, Charles Real describes the Seismic Hazard Mapping Act to assembled and Mitigating Liquefaction the consequences of that reporters, as Thomas Blake looks on. Hazards in California was behavior can be planned for produced by a committee of and damage possibly settling, lateral spreading, flow seismically induced soil lique- engineers and geologists with avoided. slides, and loss of bearing faction and landslides. academic, practicing, and capacity. The report presents an regulatory backgrounds. The The report contains recom- overview of the recommended SP 117 is an outcome of the book was published by the mendations for what methods of analysis and ad- California Seismic Hazards Southern California Earthquake constitutes an adequate dresses the common Mapping Act (SHMA), which Center. evaluation of the liquefaction technologies available to miti- requires that seismic hazards, potential of an area, along gate the effects of liquefaction. including liquefaction, be Liquefaction happens when with the hazards that arise Also discussed are the merits of evaluated and mitigated, if loose sandy soils below the from liquefaction, including soil improvement, structural needed, for all new construc- design for the effects of lique- tion in the state. The state is faction, and the inherent risks now publishing maps delineat- associated with such decisions. ing areas that are believed to be susceptible to both liquefaction The report is a summary of 18 and landslide hazard. months of study and delibera- tion in response to the With the release of SP 117, California Department of building officials in the Depart- Conservation’s Division of ment of Building and Safety of Mines and Geology (CDMG) the City of Los Angeles and the Special Publication 117, which Department of Public Works of presents general guidelines for the County of Los Angeles evaluating and mitigating requested assistance with developing standard proce- Thomas Henyey, director of SCEC, responds to a question. dures to implement the new

16 Southern California Earthquake Center Quarterly Newsletter Vol. 5, No. 1, 1999 requirements for projects re- Riverside, San Bernardino, San quiring their review. They Diego, Orange, and Ventura Workshop Will Be sought cooperation from other agreed to participate; CDMG agencies in southern California. and FEMA also lent support to Available on CD Officials from the counties of this effort. A workshop on use of the report was conducted by its authors for city and county officials and consulting engineers on June 17, 1999, at the Davidson Conference Center at USC. The full- day workshop included a chapter-by-chapter overview of the material and afternoon panel sessions for discussion and feed- back. The chapter-by-chapter overview was given using a nine-part Microsoft PowerPoint presentation and was audiotaped. The presentation will be placed onto CD-ROM along with the audio for a narrative run-through of the over- view. The afternoon panel discussion sessions were videotaped. Highlights will be placed on the CD-ROM. Questions and their answers will be included. The final product will be available Authors of the report take the stage for the afternoon discussion session. for sale from SCEC. Watch for an announcement of the CD- (l to r) Ted Smith, Arul Arulmoli, Abe Simantob, Geoff Martin, Marshall Lew, Charles Real, Thomas Blake, Juan Baez, and Les Youd. ROM’s release at www.scec.org or in this newsletter.

Liquefaction Implementation Committee The agencies’ request for assis- ity. Members of the implemen- tance was made through the tation committee were present Geotechnical Engineering to answer questions from the Geoffrey R. Martin (co-chair), Group of the Los Angeles media. Three television news Department of Civil Engineering, USC Section of the American Society stations, two radio stations, and Marshall Lew (co-chair), Law/Crandall, a Division of Law of Civil Engineers (ASCE) in two newspapers were present. Engineering and Environmental Services, Los Angeles 1997. A group of practicing K. Arulmoli, Earth Mechanics, Inc., Fountain Valley geotechnical engineers and Copies of the report can be engineering geologists was obtained by using the order Juan I. Baez, Hayward Baker, Santa Paula assembled to develop imple- form included in this newsletter Thomas F. Blake, Fugro West, Inc., Ventura mentation procedures. The or by calling 213-740-5843. Ebrahim Simantob, R. T. Frankian & Associates, Burbank liquefaction implementation T. Leslie Youd, Department of Civil and Environmental committee was organized Copies of SP117 can be ob- Engineering, Brigham Young University through the auspices of SCEC tained by sending a check for Local and state government liaisons to the committee: and convened at SCEC’s admin- $15 payable to Division of istrative headquarters at USC. Mines and Geology to P.O. Box Johnnie Earnest, Orange County Its task was to aid the several 2980, Sacramento, CA 95814. Fred Gharib, Los Angeles County counties and many cities in On the memo line of the check, J. Goldhammer, San Diego County southern California with imple- write “SP117.” Do not add tax menting SHMA for liquefaction or shipping. David Hsu, City of Los Angeles hazards and to provide an Steve Kupferman, Riverside County overview of analysis techniques Jim O’Tousa, Ventura County and methods of mitigation. Charles R. Real, DCMG The committee’s report was Wes Reeder, San Bernardino County released on April 19, 1999, and a press briefing was held at USC to announce its availabil-

Vol. 5, No. 1, 1999 Southern California Earthquake Center Quarterly Newsletter 17 SCEC’s Summer Crop

Debra Einstein Environmental Analysis & Design, UC Irvine Mark Legg, Legg Geophysical Compile Updated Fault Maps of the Southern Thumbnail Sketches California Continental Borderland (Offshore of This Year’s Interns Region) for the Master Model Personal goals: I would like to work in the field of environmental assessment and get hands-on experience. I want to learn more about faults/fault zones so that I may use that knowledge in assess- Internship program coordinator Mark Benthien recently announced ing different areas. This becomes especially important in the participants in the sixth annual SCEC Summer Internship California. Program. Here is a list of the students, their research mentors, projects and goals, and personal goals. Project goals: a project of this magnitude is important, especially for SCEC. To be able to read on a map faults/fault zones and seis- micity is especially significant for assessing types of hazards Natanya Black Geology, UC Santa Barbara accompanied by building in these areas. Tom Rockwell, CSU San Diego Reconstruction of Trench Logs as a Test for Marie Herrera Adsetts Interpreted Paleoseismic Events Geophysics, UC Santa Barbara Bruce P. Luyendyk, UC Santa Barbara Personal goals: after obtaining my under- Mapping Small-scale Crustal Deformation graduate degree, I intend to continue working using Paleomagnetic Vectors and GIS. toward my M.S. and Ph.D. My goal is to work at an academic institution doing research and teaching. I hope to do research as a geologist in seismic studies and petrology. Teaching is another very Personal goals: I’d like to understand the important aspiration for me. I want to work toward a broader research processes involved because I understand it’s a difficult understanding of geology and earth mechanics in our society. I and lengthy process. I’d like to become familiar with the geologic will endeavor to discover new geologic perspectives in my future history of this particular area and its relevant significance. I would research, and I hope to be able to convey that knowledge to oth- also like to be able to communicate this information successfully ers. in both speaking and writing. Academically, I’d like to pursue a master’s degree in the geological sciences but I must first obtain Project goals: the goals of this project are very relevant to science my bachelor’s degree. My plan is to enter graduate school by the and society, because earthquakes not only have the potential to fall of 2001. cause millions of dollars in damage and terrible loss of life, but in a more insidious way, they can produce an underlying panic or My career goal is rather unstructured at the moment. After obtain- fear in the society. One potential solution to this fear is through the ing my B.S. degree, I hope to work for the USGS as an intern to study and explanation of the earthquake phenomenon. One ele- gain some experience and attend graduate school. After complet- ment of this is to study the past occurrences of earthquakes in ing my master’s degree, I’d like to obtain a position involving Southern California to better understand how often, and when, seismology. I am also entertaining the idea of teaching either future earthquakes are likely to occur on Southern California’s geology or mathematics at a community college. many earthquake faults. Ultimately, this information can serve to lessen the anxiety that people experience as they better compre- Project goals: mapping details of the crustal rotations indicates hend that earthquakes are not random processes (acts of God), but sizes of blocks where strain has occurred. The detailed mapping rather occur in a systematic way due to loading on the Southern history of deformation is relevant because it suggests how southern California faults. Developing methods to correctly interpret past California has deformed, as well as how it may be deforming earthquakes is critical in the evolving field of paleoseismology and presently. Thoroughly understanding the patterns in paleomagnetic for the correct future assessment of seismic activity of Southern data and faults for the western transverse ranges allows for more California’s faults. This knowledge can bring a sense of security, precise predictions involving crustal rotations and fault and basin through better education and preparedness, to the society as a development for the southern California region. whole.

18 Southern California Earthquake Center Quarterly Newsletter Vol. 5, No. 1, 1999 Grant Kier Nathan Robison Geology, Sociology/Philosophy, University of Geological Engineering, University of Nevada Colorado John Anderson, UNR Seismology Laboratory Karl Mueller, University of Colorado Comparison and Refinement of Southern Determining Activity of the Oceanside de- California Seismic Hazard Analysis tachment Offshore Southern California

Personal goals: my long-term goal is to teach Personal goals: along with my wife and earth science in either a high school or college setting. I wish to daughter, I intend to grow as a family that promotes science, integrate my undergraduate studies in sociology, philosophy, and bicycle riding, and common decency. I will graduate cum laude geology toward studies of natural hazards that have the potential with a B.S. in geological engineering and expect to begin graduate to affect society. Upon completing my undergraduate work, I will study towards a doctorate in mining and geological engineering apply to master’s programs in geology at research-oriented univer- within the following year. Graduate work is also expected to sities. After completing a master’s, I hope to work in an include seismology and mechanics research. A career for the next educational setting for a geotechnical company. several years in the environmental and geologic consulting indus- try will give way to a university position after attainment of an Project goals: this project is relevant to the scientific effort to advanced degree. create a master model of seismic hazards for southern California. This project may also contribute to an understanding of uplifted Project goals: justifiable revision of attenuation models has the terraces along the California coast. Should this project provide potential to save billions of dollars in public works and public and evidence for yet unknown activity along the Oceanside detach- private construction costs. Establishment of techniques for reduc- ment, this project will have enormous societal ing the uncertainty of upper-bound acceleration models may be of impact—influencing urban planning and development and other long-term use to the science. efforts to reduce seismic hazard risk.

Kelly Schmoker Christopher Lynch Geology, CSU, San Bernardino Computer Science/Geology, CSU San Diego Sally McGill, CSU, San Bernardino Steven M. Day, CSU San Diego Paleoseismic study of the San Andreas fault Inversion of Teleseismic Receiver Functions near San Bernardino via Evolutionary Programming Personal goals: I would like to go on to gradu- Personal goals: besides my interest in the ate school in the field of geology, focusing on paleoseismic computational aspect of this project, I am intensely interested in studies. Eventually, I would like to become a professor and still do local structure and tectonics, so I’m working to develop the skills research. necessary to enable me to contribute to this area of research. I will graduate from SDSU in August and hope to continue my studies Project goals: the San Bernardino segment of the San Andreas fault through a master’s degree program in computational science represents a major hazard for the Inland Empire area. It is impor- combining computer and geological/geophysical science. tant to know how frequently this portion of the fault produces earthquakes. Previous estimates of the probability of an earthquake Project goals: I think this work fits into the SCEC goal of generating on the San Bernardino segment of the San Andreas fault were the “master model,” which includes as a main point the need to about 28 percent in the next 30 years (Working Group on Califor- determine the seismic wave velocities to use in computing theo- nia Earthquake Probabilities, 1995). This was based on assuming a retical seismograms. This code is being used to explore methods of recurrence interval of 146 years. Prior work at the Plunge Creek determining the velocity structure of the crust through inversion of site suggests that it may have been more than 350 years since the teleseismic receiver functions. By developing a range of tech- last earthquake at that site. If this is true, then either the probability niques and comparing their results we can better verify and of an earthquake in the next 30 years is more than 28 percent or constrain these results, producing a more accurate model of the the average recurrence interval is longer than the 146-year esti- Earth’s crust. From this we can learn to better understand the mate that was used to calculate this probability. Our work this tectonic forces that affect us and develop the strategies to exist summer will help to distinguish between these two possibilities. safely with seismic hazards.

Vol. 5, No. 1, 1999 Southern California Earthquake Center Quarterly Newsletter 19 Ashley Streig Adam Webber Geology, Occidental College Geology, UC Santa Barbara Kerry Sieh/Doug Yule, Caltech E. A. Keller, UC Santa Barbara Paleoseismic Investigation of the San Andreas The Earthquake Hazard for the Rincon Creek Fault at Burro Flats Anticline (RCA) and the Associated Buried Reverse Fault, Carpinteria, CA. Personal goals: I plan on attending graduate school upon my graduation from Occidental College in May 2000. Personal goals: as an undergraduate geology major, I am striving to I hope to attain both my master’s degree and Ph.D. in a field of experience a broad spectrum of fields within this major, because geology or earth sciences. This internship is a great opportunity for this is my chance. These are my academic goals, and what I hope me to gain research experience in a field where I hope to continue to achieve is an understanding for what I want to pursue in the my education. Through this research project, I hope to focus my future. I have a love for understanding the present and past pro- academic goals in the field of geology. cesses of the earth, and this is what I want to focus on in the future. I am set on going to graduate school once I have received Project goals: the seismic history in Burro Flats will help us deter- experience and an idea of what I want to pursue. Plate tectonics mine how frequently earthquakes happen in this region and how and geomorphology are two specific areas that I have recently intense the ground shaking may be. We will determine how the studied and have gained a strong interest in. I hope to follow up fault behaves in Burro Flats between San Bernardino and Indio. on these newfound interests by gaining some experience during Interestingly, this is the only segment of the San Andreas fault that the summer of 1999. has not had an earthquake in the last 200 years, so examination at this segment is important to the overall understanding of the San Project goals: the importance of this project with respect to sci- Andreas fault system. Seismic history of this region will help us ence and society is to gain a better understanding of the gauge future activity in this region. As the population of the Inland earthquake hazard that the Rincon Creek Anticline (RCA) presents Empire continues to grow, this information will help inhabitants to the city of Carpinteria, CA. By determining a rate of uplift and prepare for future earthquakes. The results of this study will show whether it was a constant rate or rapid jumps as a result of earth- us how large earthquakes are and how frequently they occur along quake activity, the threat posed to Carpinteria can be analyzed. this section of the fault, allowing assessment of risk in the area. The RCA is a typical young fold of the Santa Barbara fold belt, and by determining localized characteristics of the structure, extrapo- lated information can aid in studying the larger picture of the Santa Kathryn van Roosendaal Geophysics, CSU, Northridge Barbara fold belt. David Okaya, USC 3-D analysis of LARSE ’94 data

Personal goals: my long-term goal is to obtain at least a master’s degree in volcanology and geophysics. I am especially interested in geophysical modeling of magma chambers and other plutonic structures.

Project goals: the LARSE project is of great importance to the inhabitants of the Los Angeles basin and the San Fernando Valley. The Northridge earthquake drove home the importance of locating blind thrust faults and other structures far beneath the surface. The study is also important scientifically for its look into the structure of the lithosphere and the workings of plate tectonics.

20 Southern California Earthquake Center Quarterly Newsletter Vol. 5, No. 1, 1999 SCEC News Briefs

Many Jurisdictions in L.A. Area A public report, with audio and video tapes of the symposium’s SCEC Outreach Presentations to the Emergency proceedings, would be made available through SCEC. Preparedness Commission Andrews concluded her presentation with a request for the On June 9, 1999, Jill Andrews and Mark Benthien gave presenta- commission’s partnership in this project, which they granted. Chris tions to the Emergency Preparedness Commission for Los Angeles Wright, president of the Los Angeles chapter of the Business and County and the cities in the area. Andrews spoke about SCEC and Industry Council on Earthquake Planning and Preparedness its outreach programs, highlighting the programs that SCEC is (BICEPP) also indicated that BICEPP will partner with SCEC on this conducting with the city and county of Los Angeles, that include: project.

• A joint task force of engineers, scientists, and city and county Benthien then gave a presentation on the Los Angeles Region officials to study vulnerable buildings in Los Angeles—specifi- Seismic Experiment (LARSE II), which will be conducted in Octo- cally “tuck-under” or “soft story” structures such as the ber 1999. The study will use ultrasound-like images of faults, basin Northridge Meadows apartment building that collapsed in the depths, and other features deep in the Earth’s crust to determine Northridge earthquake—and nonductile concrete structures like where earthquakes can occur and how the ground will shake as a parking garages. result.

• A partnership with the California Division of Mines and To generate the vibrations needed to form the “seismic image,” Geology to conduct a series of workshop to educate city more than 100 small buried charges will detonated over a four-to- officials on how to use liquefaction hazard maps. [Ed. note: See five-day period along a line from Pacific Palisades to the western separate article in this issue for a description of a workshop.] Mojave Desert. To record the vibrations, 1,000 seismometers will be placed along the same line. More than 60 separate landowners Andrews also described “The Real Meaning of Seismic Risk”—a will grant permission for this joint USGS-SCEC project to be lo- proposed symposium that would feature lively exchanges among cated on their property. scientists, engineers, building officials, policymakers, insurers, developers, and the media—with the goal of encouraging public participation in and understanding of earthquake science through SCEC Will Pay for Members interactivity with SCEC. Stress-Triggering and Deformation Software Training Workshop The symposium would consist of a panel of experts with differing or opposing views who would make short presentations on urban Three pieces of software in current use for studies of earthquake seismic risk issues. Topics could include: and fault interaction will be the subject of a two-day hands-on workshop to be held in Palo Alto on September 8-9. The goal is for • A critique of methods used to interpret the earthquake threat the participants to develop sufficient skill that they will use the software in their own research and teach its use to others. • Vulnerability of tall buildings and other structures near faults The course will introduce participants to Coulomb 1.0, 3D-DEF, • Whether the “life safety” design code is the best practice, given and VISCO1D. The applications will be presented by their authors, what we now know from Northridge who will walk participants through tutorials and provide simple manuals. All software and manuals will be available electronically. • Cost-benefit analyses of various retrofitting techniques and codes for new construction To give everyone keyboard/monitor access, the workshop is lim- ited to 45 participants. Housing will be in suites at the Schwab • Socioeconomic impacts of earthquakes and secondary hazards Residential Center of the Stanford Business School. Instruction will in California vs. other natural hazards outside the state take place at the Mitchell Earth Sciences 20-station training center.

Vol. 5, No. 1, 1999 Southern California Earthquake Center Quarterly Newsletter 21 Participants will arrive on the afternoon of September 7, followed The workshop will be limited to 100 participants. Each applicant by a welcoming reception that evening. Other events include a to the workshop is asked to provide a brief statement of interests, barbecue on Wednesday evening and an afternoon run. The work- including how he or she can contribute to the goals of the work- shop is scheduled to conclude by 6 p.m. on September 9. SCEC shop. Partial support (air travel, hotel, and meals) will be provided will cover tuition, airfare within California, airport van shuttle, by workshop funds. To apply for an invitation, see: HTTP:// meals, and accommodations for its members. WWW.SCEC.ORG/NEWS/99NEWS/PBO.HTML.

Coulomb 1.0, principally written by Shinji Toda (ERI, Japan)—an The chief observational requirement of the PBO is a characteriza- evolution of GEN 1.0 by Geof King (IPG, Paris)—is a fast, menu- tion of the three-dimensional deformation field over the maximum driven Mac program rich in graphics that performs 3D elastic ranges of spatial and temporal scales. The PBO should be de- dislocation and a limited number of 2D boundary element calcu- signed to study long-term, regional tectonic processes as well as lations of deformation and stress in an elastic half-space. Ross shorter-term, smaller-scale processes that may be more closely Stein will help Shinji Toda teach this session. related to natural hazards, such as earthquakes and volcanic eruptions. 3D-DEF, written by Joan Gomberg (USGS, Memphis) and Michael Ellis (CERI, Univ. Memphis), performs elastic dislocation bound- It is proposed that the PBO be coordinated and integrated with the ary-element calculations. The program enables a variety of proposed U.S. Array and the San Andreas Fault Observatory at boundary conditions to be applied, which makes the model quite Depth (SAFOD) projects as part of the EarthScope initiative being flexible. The program and manual can be obtained via developed at NSF. In addition to advancing our basic scientific anonymous FTP to beagle.ceri.memphis.edu knowledge of active tectonic processes, the facility will in the “/pub/gomberg” directory. improve seismic and volcanic hazard assessment and contribute to earth science education and out- VISCO1D, written by Fred Pollitz (UCD) calculates reach in the U.S. the response of a spherically stratified elastic- viscoelastic medium to the stresses generated by fault slip The PBO Steering Committee consists of or dike opening occurring in one of the elastic layers. Yehuda Bock, Andrea Donnellan, Don Helmberger, Tom Henyey, Ken Hudnut, Gene Humphreys, Chris To register, or for more information, email Ross Stein at Marone, Meghan Miller, Bernard Minster, Barbara Romanowicz, [email protected]. Please indicate your choice of software, so ses- Paul Segall, Paul Silver, Bob Smith, Seth Stein, Wayne Thatcher, sions can be planned accordingly. George Thompson. The workshop is jointly sponsored by the NSF’s Division of Earth Sciences, UNAVCO, IRIS, NASA, USGS, IGPP, and SCEC. Workshop to Be Held October 3-5 Plate Boundary Observatory to Be Defined and Planned Moving to Private Sector Steven Ganz Leaves WSSPC The Plate Boundary Observatory (PBO) is a proposed facility for investigating active tectonic and magmatic processes of the Pa- Steven Ganz, first executive director of the Western States Seismic cific/Juan de Fuca–North American plate boundary through Policy Council (WSSPC), recently moved to the private sector, measurements of crustal deformation. The study of plate boundary joining an Internet start-up based in San Francisco. In that move, deformation is a research area that deserves increased attention the Earthquake Information Providers (EqIP) also loses a member of from a broad spectrum of Earth scientists. Toward that end, a its steering committee. workshop will be convened on October 3–5 in Snowbird, Utah, to help develop the plans for such an observatory. A graduate of the John F. Kennedy School of Government at Harvard, Ganz’s master’s degree is in public policy and urban The PBO Steering Committee invites participation from a broad planning. Using that background and management and entrepre- spectrum of earth scientists in a workshop to help define the PBO neurial skills during his tenure at WSSPC, he developed several concept and plan for its implementation. The workshop will pro- outstanding programs, including a state-of-the-art Web service and duce a report outlining the scientific basis for the PBO, its a series of excellent annual meetings and workshops featuring instrumentation requirements and deployment strategy. It will earthquake-related public policy issues, recent research on seismic describe the ways the facility can advance earth science research hazards in the western states, and insurance-related issues and and contribute to education and outreach. policy recommendations.

22 Southern California Earthquake Center Quarterly Newsletter Vol. 5, No. 1, 1999 He developed partnerships with other organizations that focus on Following EqIP’s approval of the revised structure, the process of seismic issues and research and was a technical advisor and leader refining the site began, under the auspices of the Multidisciplinary among such partnerships. Center for Earthquake Engineering in Buffalo:

Jill Andrews, SCEC outreach director, said, “We in the SCEC com- • Refining and filling in the contents of the database munity will greatly miss Steve’s professional approach to bringing together people in both public and private organizations to reach • Developing the Web interface to retain simplicity but add more consensus on earthquake-related public policy issues. capability

“We thank Steve for his contributions to society through associa- • Maintaining the site tion with WSSPC, and wish him all the best in his new endeavor.” • Coordinating the participation in and use of the site by EqIP In a recent message to the earthquake research community, Ganz members said of the move, “I am very sad to leave the organization, but at the same time very excited about my new opportunities. I have • Marketing the site—getting it better known and more widely thoroughly enjoy working at WSSPC. I truly believe that WSSPC is used an organization with a focused mission and a unique ability to continue making a significant impact in improving the means to A new proposal submitted to NSF will ask for support for these reduce the threat of earthquake hazards.” continuing efforts at least through the year 2000.

EQNet Developed with SCEC Participation With the Red Cross and Allstate Omnibus Earthquake Resource Site Now Online SCEC Helps Add Earthquakes to Disaster Curriculum Chairperson Jill Andrews announced that the Earthquake Informa- tion Providers (EqIP) group has finished a full revision of the SCEC has joined with the American Red Cross and the Allstate group’s Web-based catalog of earthquake-related resources. In Foundation in a project that will help teachers integrate disaster addition, the group is submitting a proposal to NSF to continue the safety concepts into their regular lesson plans. development of the site. Announced at a news conference June 1, 1999, the Children’s EQNet (WWW.EQNET.ORG), a project originally launched by EqIP in Disaster Safety Curriculum will provide lessons, activities, and 1996 is intended to be a “one-stop” source for locating Internet demonstrations that teachers can use to incorporate a hazard- sites related to earthquake hazards. Part of its purpose was to related topic into other classroom subjects. To address the very consolidate access to those resources, and part of it was to elimi- real threat of earthquakes in our region, basic earth science and nate duplication among earthquake information providers earthquake information will be included in the curriculum materi- supported by NSF. als.

All EqIP members have Web sites and links pages, all of which “Integrated curricula that use real-life or hands-on examples to require maintenance. EQNet allows them to reduce the amount of convey lessons in science, math, language arts, and social studies maintenance on their own link pages by centralizing a resource are indeed the best tools for teaching today’s students,” said they can all link to. Such a shift allows individual sites to focus on SCEC’s outreach director, Jill Andrews. “An issues-based integrated their areas of expertise. curriculum such as this one is especially valuable in light of the requirements of the new National Science Education Standards.” Ultimately, EQNet may not only be a reference tool for EqIP mem- bers (and others), but also a means of promoting and attracting The Children’s Disaster Safety Curriculum will be made available more visitors to all EqIP members’ Web sites. through local Red Cross chapters at a nominal cost. For more information, contact Rocky Lopes, Disaster Services, American EQNet’s webmaster, Ed Hensley, dismantled the original static Red Cross National Headquarters, at (703) 206-8805 or pages, redesigned the structure of the site, and remounted it as an [email protected]. online database. At the same time, he simplified the interface, making access to the information in the database easier.

Vol. 5, No. 1, 1999 Southern California Earthquake Center Quarterly Newsletter 23 Beneath the Science By Mark Benthien

A Funny Thing Happened on the Way to the Fieldwork

For this issue of the SCEC stream of lava heading our of our trench, and upside- Quarterly Newsletter, we re- direction, and it was setting fire down people in China quested anecdotal or humorous to the surrounding brush. So I beneath that. Her doodles also key. My guide and translator stories of summer field re- was tugging at the heat probe commemorated the scattered was Lieutenant Alp, an army search—the memorable with all my might, surrounded interesting events that broke up officer in the Turkish military. experiences aelong the way to by a small brush fire and an the monotony of trench log- We also had a driver. One site the final scientific result. Here approaching 3-ft-wide flow of ging, such as the discovery of a was located near a small are a few of the responses. lava. I finally gave up the fight scorpion in the trench one day Kurdish village. We stopped at and watched as the heat probe and a sidewinder under the the local military command, Shirley Baher, UCLA was buried even further by trailer another day. where Lieutenant Alp discussed While in Hawaii when I was lava. something with the local com- taking ESS135 A, B, C, we had Heidi Anderson assisted me mander. He later told me that a field trip to Kilauea to per- Sally McGill, with trench logging on the they were concerned about form magnetic and seismic CSU San Bernardino Garlock fault while she was an possible Kurdish rebel activity. experiments. While there, we I have had many interesting undergraduate geology major at We headed off to the GPS site all had to perform an extra field assistants in the course of Caltech. After graduating, she at 3 o’clock the next morning. project and write a special my paleoseismic fieldwork in took a break from geology to It was pitch black. Suddenly, section about it in our final southern California. I would study fashion design in Paris. our driver came to a complete report. I had chosen to prove This was an outgrowth of her stop as we encountered four the Curie temperature. This is summer undergraduate re- Kurdish men standing in the the temperature at which We had a Mongolian search project on the history of road carrying automatic weap- magnetization of material goes guide who was usually hoop skirts. As she learned ons. Worse, they opened up the to zero. To perform the experi- drunk and therefore not more about the history of door and piled into our car—a ment, I had a magnetometer very useful. fashion she wanted to illustrate car built for four people. Oh and heat probe. I would insert the ages of the strata in my great, I’m never going to see the heat probe into recently trenches with sketches of the my cat again. Lieutenant Alp, formed lava, Paul like to pay tribute to them not fashions that were popular at who was purposely wearing only for their dedication to those times. Eventually she civilian clothes to avoid being Davis would read the tempera- getting the work done but also returned to assist me on an- shot, started talking to them in ture, and I would record the for their cheerful spirits which other Garlock trench, but this Turkish. Meanwhile, I was magnetometer readings every made the long months in the time she brought a portable, silently praying in English. It’s minute. The two measurements field more enjoyable. Although hand-operated sewing machine night and I’m on a deserted would be combined, a graph I mention only two of my with her, and she spent her road in the middle of a foreign would be drawn, and the assistants here, I have fond evenings in the trailer sewing a country. I’m crammed into a theory could be proven (or not memories of my time with all of trench-suit for herself. Heidi is small car with six other people, proven). them. Dawn Grant, who as- now a graduate student in four of them heavily armed. As sisted with trench logging on geology at UC Berkeley. we were driving along the road, The only problem with the the Garlock and San Andreas I kept using my finger to push setup was that as the lava faults, drew beautiful, creative Shawn Larsen, Lawrence the barrel of a machine gun cooled it cemented a $200 heat doodles in the margins of the Livermore National Lab away from my head. Thinking probe along with it. To compli- logs, including a depiction of I was on Rob Reilinger’s 1989 back, it’s fortunate that the cate matters, there was a steady hell, located beneath the base GPS campaign in eastern Tur- movie “Pulp Fiction” hadn’t

24 Southern California Earthquake Center Quarterly Newsletter Vol. 5, No. 1, 1999 come out before this time. After passed, the woman had the Off-Scale we got to the site, Lieutenant decency to head for cover. On authors who are not earth scientists but wish they were Alp informed me that the army the other hand, the man stood gave these men guns and asked there scratching his rear like them to protect us from pos- Homer Simpson. He looked “One of the Three Most Interesting sible rebel activity. It turns out like him, too. It was not a pretty Spectacles I Have Beheld” that these four Kurdish men sight. were perhaps the friendliest people I have ever met. Mark Benthien, USC: After five years aboard the H.M.S. Beagle, Charles Darwin During Paul Davis’ Lake Baikal found himself becalmed off Chile in March of 1835 with time to I was on Rob Reilinger’s 1990 Teleseismic experiment, I was GPS campaign in the Imperial stationed in Mongolia along write this letter to his sister. Valley. I usually traveled solo to with a team of Russian col- my assigned sites, but this time leagues. Our seismograph Kenji Satake was with me to stations were about 50 km My dear Caroline, learn something about GPS. apart, in areas where all dirt We now are becalmed some leagues off Valparaiso and instead of The station for the night was roads and hills look identical KANE, located near the junc- and finding the stations was a growling any longer at our ill fortune, I begin this letter to you. . . . tion of the Elmore Ranch and challenge. We had a Mongo- The voyage has been grievously too long; we shall hardly know Superstition Hills faults. It’s in lian guide who was usually each other again; independent of these consequences, I continue to the middle of nowhere, only drunk and therefore not very suffer so much from sea-sickness, that nothing, not even geology accessible with a 4-wheel drive useful, and I was a 20-year-old vehicle along a dilapidated dirt kid from California—so our itself, can make up for the misery and vexation of spirit. road. We headed west towards credibility was about equal. The papers will have told you about the great Earthquake of the the site late in the day. It was One night we were late in extremely difficult to see, since arriving at the next station and 20th of February. I suppose it certainly is the worst ever experi- we were blinded by the glare had no landmarks to guide us. enced in Chile. It is no use attempting to describe the ruins—it is the from the setting sun. As we Our only help was a handheld most awful spectacle I ever beheld. The town of Concepcion is now were bouncing back and forth GPS receiver that I had pro- nothing more than piles and lines of bricks, tiles and timbers—it is trying to maintain contact with grammed with the coordinates the road, we could make out of the station. The instrument absolutely true there is not one house left habitable; some little what appeared to be a truck listed the direction we were hovels built of sticks and reeds in the outskirts of the town have not and people standing around a heading and the direction and been shaken down and these now are hired by the richest people. campsite 100 yards in front of distance to the station. As we The force of the shock must have been immense, the ground is us. No problem. It’s always approached the station, I nice to meet strangers in the pointed a flashlight ahead of traversed by rents, the solid rocks are shivered, solid buttresses 6- middle of nowhere. We moved the car so the driver (who did 10 feet thick are broken into fragments like so much biscuit. to within 50 yards. We were not speak English) could drive still blinded by the sun but “cross country” in the right How fortunate it happened at the time of day when many are out of could definitely distinguish the direction by following the spot their houses and all active: if the town had been overthrown in the outline of two people. Still, of light on the ground ahead. night, very few would have escaped to tell the tale. We were at something didn’t quite look This was in 1992, so GPS was Valdivia at the time. The shock there was considered very violent, right. At about 25 yards I new to us, and no one else in slowed and started to roll down the car trusted that I would find but did no damage owing to the houses being built of wood. I am my window. I wanted to say the site. As we got close, we very glad we happened to call at Concepcion so shortly after- hello and tell these people swerved back and forth as I wards: it is one of the three most interesting spectacles I have what we were doing. But ... oh adjusted our course until the beheld since leaving England—A Fuegian Savage—Tropical my gosh. There were a man driver slammed on the brakes and a woman standing there to stop less than 2 feet from the Vegetation—and the ruins of Concepcion. It is indeed most wonder- without any clothes on. Need- station. I guided the team for ful to witness such desolation produced in three minutes of time. less to say, I decided not to the rest of the summer. stop, and quickly rolled the —Charles Darwin, 1835 window back up. As we

Vol. 5, No. 1, 1999 Southern California Earthquake Center Quarterly Newsletter 25 Planning SCEC’s Role in Clearinghouse

SCEC Scientists Conduct First Post-Earthquake Response Planning Seminar By Jill Andrews and Mark Benthien

About 50 SCEC-affiliated re- into an official SCEC response searchers and students led by plan. The group agreed it USGS Pasadena Scientist-in- should meet again at the SCEC Charge Lucy Jones met in late annual meeting to discuss the June to organize a new plan resulting plan and logistics. around the scientific objectives of a post-earthquake investiga- Geology Group Summary tion and to discuss how those (Tom Rockwell) objectives could be achieved. Following a large earthquake, geologists need to do the fol- clearance, and transporta- real-time epicentral informa- Following a brainstorming lowing: tion to resolve extent of tion, including size, focal session, the participants broke surface rupture. This requires mechanism, etc. into three groups—geology, In the first hours: access to a helicopter, with • Resolve scope of surface direct communication back • Install quadrilaterals/ rupture. They would need an to a data collection center. alignment arrays/afterslip immediate response team Aerial photos from any studies, GPS, point align- that is ready to go, with source would be extremely ments. necessary equipment, useful. This also requires

Collaborating When It Counts The California Post Earthquake geodetics, and seismology—to Information Clearinghouse discuss the questions raised in the brainstorming session and For two weeks after the January 17, evening sharing and reviewing Within one day of the Northridge formulate post-earthquake field 1994, Northridge earthquake, the their observations. earthquake, clearinghouse field in- California Office of Emergency vestigators were on site, bringing experiments that would address Services (OES) Pasadena office That was the first extensive opera- back damage reports that aided each of those questions. At the served as the nerve center of an tion of the California Post Earthquake emergency response activities and end of the day, each group extensive reconnaissance effort. Information Clearinghouse, a focused earth science investiga- presented its conclusions, and Every morning, earth scientists, en- project of many organizations in- tions. In a few days, the daily Jones facilitated a lively session gineers, social scientists, and volved in earthquake studies. The information became an impressive that focused on implementation public policy experts headed out clearinghouse is a unique way in body of data for future analysis and methods. to the damaged areas. After a day which information can be ex- use. of looking at and studying the changed among various types of earthquake’s effects, these experts investigators who come from other Clearinghouses had been orga- The following notes outline returned to a crowded conference states and counties. nized following other California many of the ideas brought room in Pasadena to spend the quakes. The California Division of forward in each of the breakout sessions. The results of the workshop will be synthesized

26 Southern California Earthquake Center Quarterly Newsletter Vol. 5, No. 1, 1999 participants; to perhaps establish a field mapping system complete with GPS receivers for more precise locations; to compile daily a summary of all field data at a common data collection center or clearinghouse; and to publish the data as soon as possible.

• Detailed mapping; include focus on structure complexi- ties USGS, CDMG, SCEC geolo- Topics of interest for such There is also a need for a struc- gists, and others. investigations: In the first day: tured response with common • Coseismic Geodesy Group Summary • Aerial photography of the standards. This should be a (Ken Hudnut) • Stress triggering (observable rupture as soon as the collaborative effort between the Geodesists would like to have rate changes adjacent to rupture zone is established, continuous instrumentation out other faults—co-seismic so more detailed work of in the field, which would motion on neighboring documentation, including eliminate the need to rush out faults, for example.) detailed mapping and slip to the field after the event. measurements, can begin. • Campaign deployments SCIGN has not built this capa- • Slip measurements. There is bility into its program. • Instrumenting buildings a need to establish a Geodesists need GPS arrays • Long-period, long-wave- common standard of quality across the fault to measure length deformations to be followed by all displacement. • Various models to explain

Geodesists would rely on SCEC/USGS to coordinate efforts. A possible structure: • SCEC: Crustal Deformation Mines and Geology (CDMG) and leading organizations were joined March 1996 to plan for the needs Working Group (Agnew: the USGS worked with OES and by the California Seismic Safety of all the involved organizations. the Earthquake Engineering Re- Commission (CSSC). They reached logistics) search Institute (EERI) to run the an informal agreement to establish In summary, the plan calls for the • SCIGN: (Hudnut: chair modest operations out of local and operate a large clearinghouse clearinghouse to: 1) be the check- scientific integration, source school gymnasiums, firehouses, after the next major earthquake. in and check-out point for all community colleges, and even That agreement came just in time. investigators and officials who ar- modeling, feedback to motels. rive at the scene; 2) collect and Agnew’s group) Hundreds of investigators passed verify perishable reconnaissance The value of sharing information through the doors of the Northridge information; 3) convey that infor- • USGS Menlo Park: Crustal after these events was obvious, but clearinghouse during its two weeks mation to the planning/intelligence deformation mega project they also realized that the clearing- of operation. Although it as an un- function of the OES Regional Emer- (Thatcher) house was an efficient way to qualified success, it also showed gency Operations Center; 4) continued on next page involve and track the large num- the need for formal plans and the provide updated damage informa- ber of investigators who came to involvement of more organiza- tion through daily briefings and the damage scene. tions. reports; 5) track investigators in the field; and 6) perhaps even direct A few months before the The Plan their movements for maximum Northridge earthquake, the four Clearinghouse collaborators have been meeting quarterly since continued on next page

Vol. 5, No. 1, 1999 Southern California Earthquake Center Quarterly Newsletter 27 CLEARINGHOUSE continued from previous page

Seismology Group Summary • Geology + correlation to • Rupture stopping? • The need for ID cards, letters (Ralph Archuleta) site response • Subsurface structure of permission to enter The group discussed what affected areas • Non-linearity (time • Fault zone trapped waves experiments could be deployed urgency) (fault complexity) • The need to interface with to answer the scientific ques- • Coherency of near-field, California’s OES and its tions. Timing, priority, • Where is the fault? scattering array around technical clearinghouse organization, and personnel • Stress triggering borehole stations were taken into account. (modeling) • The need to invite SCEC • Ground motion and Archuleta constructed an orga- • Crustal structure? Refraction researchers to future precarious rocks nizational chart that indicated technical clearinghouse Other issues discussed by the coordination of data analysis • Deep structure meetings entire group: and modeling, communication, • Source effects—earthquake • The need for cell phones • The need to recruit volun- and field investigations, as well physics (time urgency) as considering real-time inven- and whether they are teers to continue the science tory of instruments. • Near field (source) dependable in a post- plan effort recordings [time urgent] earthquake setting Scientific questions considered • The need to conduct • Source properties included: • Walkie-talkies exercises based on scenario (temporal changes) • Site effects earthquakes • Rupture dynamics • The need to construct a Web page that could be used as a • The need to identify funds • Basin effects, basin edge, • Rupture nucleation? communications vehicle and for a post-earthquake 3D structure (good rock sites) that is password protected. scenario

COLLABORATING continued from previous page coverage with minimal disruption the emergency planning and re- Southern California Earthquake always be activated when there is to residents. sponse activities in the state. Center a federal disaster declaration.

In the few years since Northridge, Besides the members of the man- Structural Engineers Associa- In the first 24 hours after a serious the technology for capturing data agement group, ten other tion of California quake, the OES region in which the has been vastly improved, and organizations have signed on as earthquake strikes will provide, or what was a comparatively primi- participants in the clearinghouse Technical Council on Lifeline work with other governmental tive system in 1994 is now a plan: Earthquake Engineering units to arrange for, the clearing- networked geographic information house space. system capable of tracking the in- Applied Technology Council UC Berkeley Seismological vestigators as well as their findings. Laboratory The duration of the clearinghouse California Institute of operation depends on the extent of Within the clearinghouse manage- Technology Triggering a Clearinghouse the damage and the length of the ment group, CDMG and USGS are An earthquake in an urban area response period. While there is still responsible for conducting California Universities for will trigger establishing a clearing- a need for information to support seismologic and geologic assess- Research in Earthquake Engi- house when the quake is damaging response activities, or perishable ments of earthquakes. EERI has a neering and has a magnitude of 6.0 or data to be gathered, the field in- charter from the National Science above. A clearinghouse may be vestigators will survey the damaged Foundation to investigate the struc- Federal Emergency Manage- established under other conditions area. tural and social effects of all major ment Agency, Region IX if recommended by CDMG staff earthquakes in the U.S. and during initial field surveys follow- abroad. The CSSC is the main seis- National Aeronautics and ing an earthquake. mic policy body in the state, Space Administration Adapted from an article recommending new legislation and A federal disaster declaration is not published in California regulations to minimize earth- Pacific Earthquake Engineering necessary to activate the clearing- Geology, March/April 1999, by Sarah K. Nathe. quake losses. OES coordinates all Research Center house, but the clearinghouse will

28 Southern California Earthquake Center Quarterly Newsletter Vol. 5, No. 1, 1999 Uniting Science and Education

Teachers Sacrifice Yet Another Weekend By Jill Andrews

I used to think I wanted to be a authors as they develop SCEC K-12 teacher. I thought it would and SCIGN online educational be an easy career—teaching modules. straight out of texts to well- behaved students who are As I sat down to write a report motivated and eager to learn, on our second SCEC Outreach/ with lots of time to rest, read, DESC-Online Advisory Team and travel during the summer. I Workshop, held in June, I held that idyllic but erroneous started thinking about what it view for years until I began means to give up a weekend. DESC-Online workshop participants take a break from the long hours of spending a weekend each Much of a teacher’s evenings curriculum development: (l to r) Phil LaFontaine, Meridith Osterfeld, Jill Andrews, Katrin Hafner, Cindy Anderson. quarter with a group of ridicu- and weekends are already filled lously busy, hard-working with planning, grading, train- teachers and teacher trainers ing, or researching. Why give up four more weekends to help quake Studies” (SCIGN.JPL.NASA.GOV/ who are advising our Web with someone else’s project? LEARN). Here’s how we did it.

Their answer: it’s for a good Midnight, Friday, June 4: All the cause. Teachers are greatly in preparations for the workshop need of well-constructed, user- were complete. SCEC staff DESC-Online Background friendly earth-science curricula members and Web authors all aligned with the national stan- arrived hours earlier at the dards. Our DESC-Online motel near UC Santa Barbara, In early 1998 SCEC launched a formal review and testing of its educational materials under development, with a commit- project offers an opportunity for but so far none of the teachers ment to bringing the Web-based products online as quickly as teachers to collaborate with were there, and I was worried. possible. The scientific review, now complete, focused on sci- scientists to produce a first-rate Did they have the right date? entific accuracy and pedagogical effectiveness. At the same Web-based teaching and learn- Since it was so late, there was time, we assembled a group of educators to work with our ing tool for middle school and nothing to do but go to bed and Web authors to test the existing modules and help us create a new module for middle and high school students. The group, high school students. hope they arrived by morning. called the Development of Earth Science Curricula (DESC) Online Advisory Group, has met four times to date (with an- Over the course of those two Had I known these people other three weekends scheduled through the remainder of days in June, we immersed better, I wouldn’t have worried. SCEC’s fiscal year) and has completed a design and storyline ourselves in learning what it Having spent all day in a train- for the new module. Between workshops, group members work and communicate via the Internet to further develop portions of takes to create and flesh out a ing workshop in Orange the modules to present at subsequent workshops. The Web au- storyline for a middle school County, they started out about thors use input from the advisors and add graphics, illustrations, version of our two existing 10 p.m. and drove from Irvine animated text, etc. to make the material dynamic and interest- modules—“Investigating Earth- to Santa Barbara. Although ing for both teachers and students. quakes through Regional Seis- Meridith Osterfeld, Phil micity” (WWW.SCECDC.SCEC.ORG/ LaFontaine, Cindy Anderson, MODULE) and “Exploring the Use and Don Whisman got only a of Space Technology in Earth- few hours’ sleep, they were up

Vol. 5, No. 1, 1999 Southern California Earthquake Center Quarterly Newsletter 29 students should know, called related to the topic. A teacher’s The fourth “A” is “Assessment,” Meridith Osterfeld— “prethinking” the learning goal is to construct a storyline which is conducted before, Regional Director, K-12 process. Using earthquakes as that students can learn from, during, and after lessons. A Alliance an example, we came up with that is rigorous, and that meets lesson that covers waves, for the following ideas: the requirements of the stan- example, should include teach- Phil LaFontaine— dards. ers’ background information on Earthquakes happen in differ- the topic—called “front load- Regional Director, K-12 ent areas for different reasons. The third “A” stands for “Acces- ing” the concepts—so teachers Alliance sibility.” All students in can anticipate students’ ques- Earthquakes have conse- California, for example, should tions. Assessment during and Cindy Anderson— quences, but with mitigation, have access to knowledge. This after is equally important to Regional Director, K-12 we can change these. requirement gives rise to “Deci- ensure that students are under- Alliance & 6th grade sion Point Assessment”—i.e., if standing and retaining the teacher at Vista Unified Earthquakes reshape the earth. some students don’t “get it,” the knowledge. School District teacher has to figure out what Earthquakes are the result of needs to be done to help those what the earth is doing— students learn. Don Whisman— constantly changing. (This Staff Developer, K-12 concept is known as a “Big Alliance & 8th grade Idea.”) teacher at Tierra Del Sol Middle School Earthquakes are measurable. A Portion of the Ursula Sexton— This exercise leads to state- ments of what we think Middle School Module the first elementary students should know. teacher to win the Presi- Unifying Concept: Earth processes create changes that are dential Award The second “A”—“Augmenta- observable and measurable over time. tion”: This step asks the Module Concept: The Earth changes through a process called teacher to decide what makes “plate tectonics.” early and ready for work on sense to students. What tools Subconcept #1: Observations provide evidence of changes Saturday. Ursula Sexton, the do students need, what in the Earth. other member of the group, “hooks” should exist in a • Observations are made using a variety of tools. arrived later that morning. package that will make them • Observations of local land forms and/or local structures/ remember what they learn. features and formation of a hypothesis of how it came to be. The ABCs of the 4As Research shows that most • A compilation of detailed, local observations leads to a 9 a.m., Saturday, June 5: After students retain information if larger/regional/global picture. introductions, Phil gave the it is conveyed in the format of • The present is a key to the past. Patterns of observations have helped to build a unifying theory called “plate tecton- group a clear explanation of the a story—especially if it’s a ics.” all-important storyline, the story that is relevant to the basis for constructing a usable student’s life. Subconcept #2: Plate tectonics explains important features curriculum. The standards, he of the Earth’s surface and major geologic events. explained, include what should During the process of aug- • The Earth is layered (clues on the surface provide clues to be taught but not how to teach mentation, a teacher develops what’s below). it. Their “4A” model was devel- a storyline, starting with the • Lithospheric plates move at the rate of centimeters per year oped, he explained, to aid “Big Idea” and moving in response to movement in the mantle. • Major geologic events result from these plate interactions and teachers in constructing a through general concepts, motions. storyline that addresses the appropriate levels of subcon- “how” and the “what.” cepts. Each component leads Subconcept #3: Major geologic events impact society. the student to the next. If the In the 4-A model, the first “A” story makes sense and is a stands for “Alignment”—identi- memorable one, it is easily fying what teachers think recalled, along with the facts

30 Southern California Earthquake Center Quarterly Newsletter Vol. 5, No. 1, 1999 Getting Down to Sixth-Grade on the level of a sixth grader— Level a most effective way to create Noon: Following the 4A over- a science-based storyline. view, Meridith and Cindy led CalendarAugust 1999 October 1999 the group through a “Star Lab” Putting the Pieces Together 5-8 SCEC Intern Colloquium 1-Nov 15 Los Angeles—LARSE II Experiment. Interested parties and activity to demonstrate how 2:00 p.m.: Facilitated by 9-12 Ninth International volunteers needed. Contact Mark some middle school students Meridith, the group began the Conference on Soil Dynamics and Benthien, SCEC Outreach. Earthquake Engineering (SDEE ’99). learn about tectonics and the time-consuming but rewarding Sponsors: Institute of Solid Earth 3-5 Snowbird, Utah—Plate Earth’s interior. This meant that process of creating an earth Physics, University of Bergen, Boundary Observatory (PBO) we first had to imagine our- science storyline, Big Idea, Norwegian Society for Earthquake Workshop: to apply, see HTTP:// Engineering. Bergen, Norway. WWW.SCEC.ORG/NEWS/99NEWS/ selves as sixth graders (not hard concepts, and subconcepts for Contact: K. Atakan, email: PBO.HTML. for some of us), crawl inside the a new middle school module. [email protected]; WWW.IFJF.UIB.NO/ giant air-filled sphere they had The product will be an 8- to- SEISMO/SDEE99.HTML. 13 California Post-Earthquake Information Clearinghouse Meeting, brought with them, and view a 12-week segment of 32 15-30 Field trip to western Turkey: Oakland, CA. For more informa- depiction of the Earth’s tectonic 50-minute lessons. Extensional tectonics, modern and tion, contact T. Toppozada, CDMG historical earthquake surface breaks Sacramento. plates with the aid of a laser and archaeoseismology. 90 (212) disc that projected an image on Finishing the Job 285 6299; 90 (212) 285 6210, 27-28 Sixth Annual Congress on the inner skin of the sphere. Sunday, June 6: After dinner fax; [email protected] OR Natural Hazard Loss Prevention. [email protected] Sponsor: Institute for Business and and a late-evening Saturday Home Safety. Memphis, TN. After viewing the plates in filled with talk about our work, 31–Sept 2 Autonomous Data- Contact: (617) 292-2003; fax: Gathering Systems in Extreme (617) 292-2022; email: motion, we moved to a labora- homes and hobbies, we were Environments, Jet Propulsion [email protected]; WWW.IBHS.ORG. tory where we performed an tired when Sunday morning Laboratory, Pasadena, CA. Abstract experiment that illustrated the rolled around, but were ready and reg. deadline: July 15. Contact: 27-29 Second Meeting on Andrea Donnellan, JPL, 818-354- Seismology and Seismic Engineer- processes at work in the Earth’s to finish what we’d begun. Our 4737, [email protected]; ing of Mediterranean interior. As “students,” we were goal was to provide the Web HTTP://GEODYNAMICS.JPL.NASA.GOV/ Countries—Sismica99. Faro, ANTARCTICA. Portugal. Tel/fax: +351 (0)89 asked to explain what we authors with enough informa- 803561 (ext. 6545); fax: +351 thought was occurring in our tion to start the process of September 1999 (0)89 823539; email: liquid-filled beakers as we reworking our community- 6-9 Western States Seismic [email protected]; WWW.UALG.PT/ Policy Council 21st Annual EST/ADEC/SISMICA99/SISMICA99GB/ dropped dye into the liquid and college level modules into a Conference. Santa Fe, New INDEX.HTM. moved a burner underneath to product appropriate for middle Mexico. Contact: WSSPC, (415) November 1999 heat the liquid. Most of us school. Jim Russell, vice presi- 974-6435; fax: (415) 974-1747; email: [email protected]. 18 USC—Science Seminar. figured out that we were learn- dent for education and Topic: To be announced ing about the process involved outreach for the Institute of 7-9 Stress Triggering and Deformation Software Training December 1999 with the Earth’s core heating Business and Home Safety was Workshop. For information, see 13-17 Fall American Geophysical the magma, causing convection a welcome observer who gave WWW.SCEC.ORG/NEWS/99NEWS/ Union meeting, San Francisco, CA. and thus tectonic activity. We us the societal impact point of STRESS.HTML. See HTTP://EARTH.AGU.ORG/ MEETINGS/SM99TOP.HTML. were told that when students view. The group continued to 20 USC—Davidson Confer- are in a lab setting, learning the flesh out the outline and fin- ence Center: Science Seminar: 16 USC—Science Seminar. HAZUS Demonstration and Topic: To be announced “hands-on” way as we were ished in time for lunch together Discussion; Active faulting and doing, they become completely before parting company. earthquake hazards in the Los January 2000 engrossed in the process and Angeles metropolitan area. 20 USC—Science Seminar. Topic: To be announced behavior problems are nearly Driving home late that after- 27-29 SCEC Annual Meeting, nonexistent. noon, I was pleased with what Palm Springs, CA. Contact SCEC, 213/740-5843 or see 30-Feb 4 12th World Conference on we had accomplished and WWW.SCEC.ORG. Earthquake Engineering. Auckland, After our experiment, we grateful to those already over- New Zealand, P.O. Box 2009, viewed a video that used ani- committed teachers for 26-30 California Emergency Auckland, New Zealand; Services Association Annual tel: 64-9-529 4414; mated graphics and film spending yet another weekend Conference and Training: “Defining fax: 64-9-520 0718; footage to help the teachers improving the nation’s science 21st Century Emergency Manage- email: [email protected]; explain what we had just seen, education curricula. All of us— ment, Managing Reality vs. WWW.CMSL.CO.NZ/12WCEE; Perceptions in a Media World.” also see WWW.EERI.ORG/MEETINGS/ touched, and learned. By the scientists, parents, and students Palm Springs, CA. Contact: Wendy 12WCEE.HTML. time we were finished (the alike—can be thankful for that Milligan, (805) 644-0899; fax: (850) 642-2883; email: Phone 213/740-1560 for SCEC Outreach whole process took about two kind of dedication. [email protected]. Phone 213/740-5843 for General Information hours), we were ready to think Fax 213/740-0011 Email: [email protected]

Vol. 5, No. 1, 1999 Southern California Earthquake Center Quarterly Newsletter 31 PublicationsThe following is a list of recent publications based on SCEC-funded research. 412. Ward, S. N., On the Consistency of Earthquake Moment Rates, SCEC authors must obtain SCEC contribution numbers for all papers to acknowl- Geological Fault Data, and Space Geodetic Strain: The United States, edge SCEC funding. In return, their papers are added to the SCEC Publication Geophysical Journal International, 134, pp. 172-186, 1998. Database. This database is reported to the NSF during each SCEC evaluation. To receive a SCEC contribution number, complete the online form at WWW.SCEC.ORG/ New and dense space geodetic data can now map strain rates over RESEARCH/SCECNUMBER.HTML, which requires authors, title, publication name, abstract continental-wide areas with a useful degree of precision. Stable strain (very important), and any other bibliographic information available. The SCEC indicators open the door for space geodesy to join with geology and number will be returned via email along with the proper NSF/USGS/SCEC seismology in formulating improved estimates of global earthquake acknowledgement statement. recurrence. In this paper, 174 GPS/VLBI velocities map United States’ strain rates of <0.03 to >30.0 x10-8/y with regional uncertainties of 5 to 50%. The SCEC Quarterly Newsletter now publishes the references only for published Kostrov’s formula translates these strain values into regional geodetic articles, no longer listing ones that are submitted, in review, in press, etc. The moment rates. Two other moment rates, M_seismic and M_geologic complete list (both searchable and sortable) is available at WWW.SCEC.ORG/RESEARCH extracted from historical earthquake and geological fault catalogs, contrast PAPERS.HTML and will no longer be printed in the newsletter in its entirety each year. the geodetic rate. Because M_geologic, M_seismic and M_geodetic derive A hardcopy version of the list can be obtained by calling 213-740-5843 or from different views of the earthquake engine, each illuminates different emailing [email protected]. features. In California, ratios of M_geodetic to M_geologic is 1.20. The near consistency points to the completeness of the region’s geological fault data and to the reliability of geodetic measurements there. In the Basin and 277. McGill, S. F. and C. M. Rubin, Surficial Slip Distribution on the Central Range, Northwest and Central United States, both geodetic and seismic Emerson Fault During the 28 June 1992 Landers Earthquake, Journal of greatly exceed geologic. Of possible causes, high incidences of understated Geophysical Research, 104, no. B3, pp. 4811-4833, 1998. and unrecognized faults most likely drive the inconsistency. The ratio of M_seismic to M_geodetic is everywhere less than one. The ratio runs 384. Madariaga, R., K. Olsen, and R. Archuleta, Modeling dynamic rupture systematically from 70-80% in the fastest straining regions to 2% in the in a 3D earthquake fault model, Bulletin of the Seismological Society of slowest. Although aseismic deformation may contribute to this shortfall, I America, 88, pp. 1182-1197, 1998. argue that the existing seismic catalogs fail to reflect the long-term situation. Impelled by the systematic variation of seismic to geodetic moment rates 391. Day, S. M., Efficient Simulation of Constant Q using Coarse-Grained and by the uniform strain drop observed in all earthquakes regardless of Memory Variables, Bulletin of the Seismological Society of America, magnitude, I propose that the completeness of any seismic catalog hinges 88,1051-1062,1997. on the product of observation duration and regional strain rate. Slowly straining regions require a proportionally longer period of observation. 396. Jackson, D. D. and Y. Y. Kagan, VAN method lacks validity, EOS, Characterized by this product, gamma distributions model statistical Transactions of the American Geophysical Union, 79, no. 47, pp. 573 and properties of catalog completeness as proxied by the ratio of observed 579, 1998. seismic moment to geodetic moment. I find that adequate levels of completeness should exist in median catalogs of 200 to 300 year duration Varotsos and colleagues (the VAN group) claim to have successfully in regions training 10-7/y (comparable to southern California). Similar predicted many earthquakes in Greece. Several authors have refuted these levels of completeness will take more than 20,000 years of earthquake data claims, as reported in the May 27, 1996, special issue of Geophysical in regions straining 10-9/y (comparable to southeastern United States). Research Letters and a recent book, A Critical Review of VAN [edited by Predictions from this completeness statistic closely mimic the observed Lighthill, 1996]. Nevertheless, the myth persists. In the letter we summarize M_seismic to M_geodetic ratios and allow quantitative responses to why the VAN group’s claims lack validity. previously unanswerable questions such as: “What is the likelihood that the seismic moment extracted from a earthquake catalog of X years falls within 407. Bazzurro, P., and C. A. Cornell, Disaggregation of Seismic Hazard, Y% of the true long term rate?” The combination of historical seismicity, Bulletin of the Seismological Society of America, 89, no. 2, pp. 501-520, fault geology and space geodesy offers a powerful tripartite attack on 1999. earthquake hazard. Few obstacles block similar analyses in any region of the world. 408. Hearn, E. H., and E. D. Humphreys, Kinematics of the Southern Walker Lane Belt and Motion of the Sierra Nevada, California, Journal of Geo- 413. Trecker, M. A., L. D. Gurrola and E. A. Keller, Oxygen Isotope physical Research, 103, pp. 27033-27049, 1998. Correlation of Marine Terraces and Uplift of the Mesa Hills, Santa Barbara, California, U.S.A., Late Quaternary Coastal Tectonics (probably) Spec. Publ. Deformation in the southern Walker Lane Belt region of the southwestern Geol. Soc. London, 146, pp. 57-59, 1998. Great Basin accommodates significant portions of both Pacific-North America transform motion and Basin and Range extension. However, Resolving marine terrace chronologies is critical for determining uplift rates apparent kinematic inconsistencies between geodetic and fault slip data in along tectonically active coastlines. Unfortunately, lack of suitable dating this region make it difficult to understand the nature of the interaction materials often makes it difficult to establish the chronology. We present between these processes. Kinematic modeling of the region in applied to here oxygen isotopic data from 21 shells of Olivella biplicata from four this region in a manner that enforces kinematic consistency and simulta- marine terraces in the Santa Barbara and Ventura area located in southern neously includes fault geometry and slip rate data, GPS survey data, and California, U.S.A. Uranium series analysis of two fossil corals Balanophyllia VLBI/VLBA site velocity data. A model is found that is consistent with the elegans from two Santa Barbara area marine terraces yielded ages of 47 ka set of available data, and this model differs significantly from prior models +/- 500 yrs and 70 +/- 2 ka (oxygen isotope stage 3a and 5a, respectively) for the region. Our model has the Sierra Nevada block, which bounds the Gurrola et al. 1996 and 1997). Olivella shells from these dated calibration Great Basin to the west, moving N49W +-1 at a rate of 12.7 +-0.5 mm/yr, points yield average values of 1.117" and 0.627" respectively. Mollusks with only minor amounts of counterclockwise rotation. Garlock fault slip is from undated terraces hypothesized to be of the same age yielded average a consequence of the relatively great westerly motion of the Sierra Nevada, values of 1.010" and 0.751" respectively. The data indicate that stable which lies immediately north of the Garlock Fault. We also find that the oxygen isotopic signatures preserved in marine terrace mollusks can southern Great Basin adjacent to our study area moves westward at a rate provide a useful tool for correlating undated terraces to those of known of about 2.5 mm/yr, which is slower than the velocity in the central Great age, as well as for correlating terraces across faults and folds. Using isotopic Basin. data coupled with a U-series dated wave-cut platform we calculate a rate

32 Southern California Earthquake Center Quarterly Newsletter Vol. 5, No. 1, 1999 of uplift ranging from 0.62 +/- 0.03 mm/yr (where the elevation of the first One of these represents cubic anharmonicity, and we set in to agree with emergent terrace is 41 m) to 0.54 +/- 0.05 mm/yr (where the first emergent laboratory observations of harmonic distortion. The other parameter terrace is at 36 m) for marine terrace flights preserved on the Mesa hills controls the amount of hysteresis, and it is set to approximate stress-strain anticline located in the city of Santa Barbara, California. curves measured in laboratory uniaxial stress experiments on Berea sandstone by Boitnott and Haupt. The constitutive equations, though 414. Vidale, J. E., D. C. Agnew, M. J. S. Johnston and D. H. Oppenheimer, fundamentally nonlinear and rate-independent, have a superficial, formal Absence of earthquake correlation with Earth tides; an indication of high resemblance to viscoelasticity, which we exploit to produce an efficient, preseismic fault stress rate, Journal of Geophysical Research, 103, pp. stable numerical algorithm. We solve 1D wave propagation problems for 24567-24572, 1998. this constitutive model using both finite difference and pseudospectral methods. These methods are shown to reproduce, to high precision, 417. Bowman, D. D., G. Ouillon, C. G. Sammis, A. Sornette and D. analytical results for quasi-harmonic wave propagation in a nonlinearly Sornette, An Observational Test of the Critical Earthquake Concept, Journal elastic medium. of Geophysical Research, 103, no. 24, pp. 359-372, 1998. Application of the Berea sandstone model to quasi-harmonic wave We test the concept that seismicity prior to a large earthquake can be propagation shows several departures from results obtained with nonlinear understood in terms of the statistical physics of a critical phase transition. In elasticity. The Berea model shows more rapid decay with distance of the this model, the cumulative seismic strain release increases as a power-law fundamental frequency component, due to nonlinear, amplitude- time-to-failure before the final event. Furthermore, the region of correlated dependent attenuation, than does nonlinear elasticity. The Berea model seismicity predicted by this model is much greater than would be predicted also shows enhanced excitation of the order 3 harmonic, in agreement from simple elasto-dynamic interactions. We present a systematic with laboratory observations. In addition, the growth with propagation procedure to test for the accelerating seismicity predicted by the critical distance of the harmonics of the source excitation shows a saturation, point model and to identify the region approaching criticality, based on a relative to the nonlinear elasticity results. This behavior reflects the comparison between the observed cumulative energy (Benioff strain) competing effects of amplitude growth via energy transfer from the source release and the power-law behavior predicted by theory. This method is frequency, and energy dissipation due to hysteresis, the dissipation used to find the critical region before all earthquakes along the San Andreas increasing as the harmonic amplitude grows. In additional numerical system since 1950 with M 6.5. The statistical significance of our results is experiments, we find that a two-frequency source function generates assessed by performing the same procedure on a large number of randomly harmonics with frequencies which can be expressed as linear combina- generated synthetic catalogs. The null hypothesis, that the observed tions of integer multiples of the two source frequencies, in agreement with acceleration in all these earthquakes could result from spurious patterns published laboratory results for other solids. generated by our procedure in purely random catalogs, is rejected with 99.5% confidence. An empirical relation between the logarithm of the 434. Sato, T. and H. Kanamori, Beginning of earthquakes modeled with the critical region radius (R) and the magnitude of the final event (M) is found, Griffith’s fracture criterion, Bulletin of the Seismological Society of such that log R µ 0.5 M, suggesting that the largest probable event in a America, 89, no. 1, pp. 80-93, 1998. given region scales with the size of the regional fault network. We present a source model for the beginning of earthquakes based on the 419. Harris, R. A. and R. W. Simpson, Suppression of Large Earthquakes by Griffith’s fracture criterion. The initial state we choose for this model is a Stress Shadows—A Comparison of Coulomb and Rate-and-State Failure, critical state of pre-existing circular fault, which is on the verge of Journal of Geophysical Research, 103, pp. 24439-24451, 1997. instability. After the onset of instability, the fault grows with a progressively increasing rupture speed, satisfying the condition of fracture energy 420. Harris, R. A., Stress Triggers, Stress Shadows, and Implications for balance at the crack tip. We investigate the difference in rupture growth Seismic Hazard, Journal of Geophysical Research, 103, pp. 24347-24358, patterns in two classes of models, which are considered to represent end- 1997. member cases. In the first model (Spontaneous Model), we assume that the surface energy varies smoothly as a function of position in the crust. In this 429. Ward, S. N., On the Consistency of Earthquake Moment Release and model, faults with small initial dimensions grow in the medium with small Space Geodetic Strain Rates: Europe, Geophysical Journal International, surface energy, and those with large initial dimensions, in large surface 135, pp. 1011-1018, 1998. energy. The rupture velocity increases progressively until it reaches its limiting velocity. The synthetic velocity seismogram at far-field shows a In this article, 141 VLBI/SLR/GPS velocities map European strain rates from weak initial phase during the transitional stage. The time taken to reach the <0.09x10^-8/y to >7.0x10^-8/y with regional uncertainties of 20 to 50%. limiting velocity is proportional to the initial length of pre-existing fault. Kostrov’s formula translates these strain values into regional geodetic Therefore the duration of the weak initial phase scales with the initial moment rates M_geodetic. Two other moment rates, M_seismic extracted length of fault. In the second model (Trigger Model), we envisage that there from a 100-year historical catalog, and M_plate taken from plate-tectonic are many pre-existing faults in the crust with various length. These faults models, contrast the geodetic rates. In Mediterranean Europe, the ratios of are stable because they encounter some obstacle at their ends (e.g. fault M_seismic to M_geodetic stand between 0.56 and 0.68. In Turkey the ratio segmentation, strong asperity etc). This situation is modeled with a local falls to 0.18. Although aseismic deformation may contribute to this deficit, increase in the surface energy near the ends of fault. An earthquake is the magnitudes of the shortfall coincide with the variations expected in triggered when the obstacle is suddenly removed (i.e., sudden weakening) 100-year catalogs. or the stress is suddenly increased locally to overcome the obstacle. Once an earthquake is triggered then the fault growth is governed by the ambient 431. Xu, H. S. M. Day, and J. B. Minster, Model for Nonlinear Wave surface energy. In this model, the rupture speed attains its limiting velocity Propagation Derived from Rock Hysteresis Measurements, Journal of almost instantly. The synthetic velocity seismogram at far-field shows an Geophysical Research, 103, pp. 29915-29929, 1998. abrupt, linear increase in amplitude without the weak initial phase that appears in the Spontaneous Model. The Spontaneous Model is character- We develop a method for modeling nonlinear wave propagation in rock at ized by a small trigger factor and the Trigger Model by a large trigger factor, intermediate strain levels, i.e., strain levels great enough that nonlinearity where the trigger factor is defined as a fractional perturbation of the surface cannot be neglected, but low enough that the rock does not incur energy at the ends of fault relative to the ambient surface energy. Thus, the macroscopic damage. The constitutive model is formulated using a seismic initiation phase with and without the slow initial phase can both singular-kernel endochronic formalism, and this formulation is shown to occur depending on the trigger factor. The variability in the observed satisfy a number of general observational constraints, including producing seismic initiation phase may represent a variation of surface energy a power law dependence of attenuation (Q-1) on strain amplitude. Once (strength) distribution surrounding the pre-existing cracks. No simple the elastic modulus is determined, and a second parameter fixed to give Q- model can explain the scaling relation between the nucleation moment 1 linear in the strain amplitude, the model has 2 remaining free parameters. and the eventual size of earthquake.

Vol. 5, No. 1, 1999 Southern California Earthquake Center Quarterly Newsletter 33 Southern California Earthquake Center Field Trip Guides University of Southern California S C E C Los Angeles, CA 90089-0742 Palos Verdes Peninsula—Written for teachers and students as well as the Phone: 213-740-1560 Fax: 213-740-0011 general public, this guide offers a lively narrative on a number of sites at Products and Publications Order Form which to observe fossils, rock structures, and faults. Two foldout maps are included. Name: ______

Organization: ______Address: ______Palos Verdes Fault—This field trip guide is designed for engineers, ______geotechnical professionals, and earth scientists. Unlike the broad infor- Telephone: ______Fax: ______E-mail: ______mation provided in the Palos Verdes Peninsula field trip guide, this guide focuses on the Palos Verdes fault. Included is a discussion of the fault as ITEM PRICE QUANTITY TOTAL Putting Down Roots in Earthquake Country (10 minimum) $1.00* a whole as well as information pertaining to the many sites along the Non-profit organization reduced rate (10 minimum) $0.50* Shipping: $3.00 + $0.05 for each copy over 10 copies <------route. Future Seismic Hazards... (Phase I) $15.00 Seismic Hazards... 1994 to 2024 (Phase II) $5.00 SCEC Quarterly Newsletter: One year (4 issues) $25.00 Newport-Inglewood and Whittier-Elsinore Fault Zones—Rather than Two years (8 issues) $40.00 offering a route to follow for a field trip, this guide discusses the two fault Field Trip Guides Palos Verdes Peninsula $5.00 zones, allowing the reader to design his or her own trip. Emphasis is on Newport-Inglewood and Whittier-Elsinore $5.00 the methods scientists use to learn about faults, such as trenching. Palos Verdes Fault Field Trip $5.00 C-Cubed Task Reports: Complete Set $250.00 Individual reports: Indicate quantity after each item Caltrans/City of Los Angeles/County of Los Angeles Task Reports H-1 $100.00__ H-2 $25.00__ H-3 $10.00__ H-4 $25.00__ H-5 $100.00__ H-6 $20.00__ The Task H-1 report describes improved empirical models for scaling the H-7 $40.00__ H-8 $50.00__ H-9 $25.00__ Printed Workshop Proceedings: amplitudes of earthquake response spectra for the southern California Earthquakes and Insurance I $15.00 region. (3 volumes) Recommended Procedures for Implementation of DMG SP 117 (Analyzing and Mitigating Liquefaction in Calif.) $10.00 TOTAL: The Task H-2 report focuses on potential destructive earthquakes along the Hollywood and Santa Monica faults. Please make checks payable to USC : Your check number: ______Mail this form to the address above. The Task H-3 report examines the use of weak motion amplification Credit card: VISA MC DISC Number:______, Exp. date: ______Fax this form to 213-740-0011. Signature:______factors for microzonation, and the relationship between weak and strong Your card will be billed by USC motion amplification.

Tax included in all prices. Shipping & handling included except for Roots The Task H-4 report describes the development of empirical models for Our Tax I.D. # is 95-1642394. scaling duration of strong ground motion by utilizing regression analyses * Price is reduced for quantities of 1000 or more. Call 213-740-0323 for details. of recorded data.

The Task H-5 report describes the compilation of a GIS based geotechnical database of the Los Angeles Basin for use in strong ground Publication Descriptions motion site characterization. (3 Volumes) The Task H-6 report documents the earthquake performance and lique- faction-related damage to bridges in the magnitude 7.8 Luzon, Putting Down Roots in Earthquake Country—The U.S. Geological Philippine earthquake (July 1990), and the magnitude 7.5 Costa Rican Survey and SCEC produced two million copies of this illustrated 32-page earthquakes (April 1991). color publication. Its message is that earthquakes are inevitable but understandable and that damage and serious injury are preventable. The Task H-7 report demonstrates seismic hazard analysis methodology with respect to selected sites in the Los Angeles basin, and illustrates Future Seismic Hazards in Southern California, Phase I: Implications of several methods for generating acceleration time histories. the 1992 Landers Earthquake Sequence—Primarily a study of the impli- cations of the Landers earthquake, this report discusses the recent The Task H-8 report describes the use of geotechnical data to reassess increase in the frequency of earthquakes in southern California. and improve the Los Angeles geological database used to develop liquefaction potential maps. This report complements Task H-5. Seismic Hazards in Southern California: Probable Earthquakes, 1994 to 2024 (Phase II)—This report represents a major advance in our knowl- The Task H-9 report focuses on the cataloging of available strong motion edge of how often shaking from earthquakes in specific areas of southern records for vertical ground acceleration time histories, together with the California will be strong enough to cause moderate damage. computed acceleration response spectra.

SCEC Quarterly Newsletter—Features include contributions by SCEC Recommended Procedures for Implementation of DMG Special Publi- scientists and working group participants; a compilation of currently cation 117: Guidelines for Analyzing and Mitigating Liquefaction available resources, published materials, and databases; a “Fault of the Hazards in California is intended to help engineers, geologists, and Quarter,” showcasing a southern California fault; and an interview with building officials evaluate and take protective measures against the a prominent SCEC scientist in each issue. potential liquefaction hazard in many areas of southern California.

34 Southern California Earthquake Center Quarterly Newsletter Vol. 5, No. 1, 1999 Southern California To Subscribe: One year’s subscription costs Earthquake Center $25.00. Please make payment by check, money order, or purchase order payable to “University of Southern California/SCEC.” Do not send currency. Price includes postage A National Science Foundation National Science and Technology Center in partnership with the within the U.S. Overseas airmail costs or spe- United States Geological Survey cial courier services will be billed. SCEC scientists, students, and affiliated agencies receive this newsletter free. Administration Mail your name, mailing address, phone number, email, and check for $25 to: Thomas Henyey Southern California Earthquake Center Center Director University of Southern California Los Angeles, CA 90089-0742 Bernard Minster Acting Science Director Subscribers: Check your mailing label for the last issue of your current subscription. If “free” John McRaney is listed, you will continue to receive the news- Director of Administration letter indefinitely. If any changes need to be made to your address, please call 213-740- Jill Andrews Outreach Director 5843 or email [email protected] Newsletter on the Web: WWW.SCEC.ORG/NEWS Board of Directors

Bernard Minster, Chairman Scripps Institution of Oceanography University of California, San Diego

John Anderson University of Nevada, Reno

Have questions? Call, fax, or email: Ralph Archuleta Tel: 213/740-1560 University of California, Santa Barbara Fax: 213/740-0011 Email: [email protected] Subscription Info Robert Clayton California Institute of Technology

James Dolan SCEC Quarterly Newsletter University of Southern California Ken Hudnut A component of the Center’s Outreach Program United States Geological Survey For more information on the SCEC Outreach Program, David Jackson see the Outreach Web page at University of California, Los Angeles WWW.SCEC.ORG OR contact: Thomas Rockwell San Diego State University Jill Andrews, Outreach Director 213/740-3459 or [email protected] Nano Seeber Mark Benthien, Outreach Specialist Lamont-Doherty Earth Observatory of Columbia University 213/740-0323 or [email protected] Ed Hensley, Newsletter Editor [email protected]

Vol. 5, No. 1, 1999 Southern California Earthquake Center Quarterly Newsletter 35 Inside SCEC Newsletter This Issue Contributors

Featured SCEC Quarterly Newsletter is published quarterly by the Southern Interview: John Anderson ...... 3 California Earthquake Center, University of Southern California, Los Angeles, CA 90089-0742, USA, telephone 213/740-1560 or 213/ Rose Canyon Fault ...... 10 740-5843, fax 213/740-0011, email: [email protected]. Report: Evaluating Liquefaction Hazard ...... 16 SCEC’s Summer Interns ...... 18 Editor Ed Hensley Planning SCEC’s Role in Post Earthquake Clearinghouse ...... 26 Feature Writer SCEC and Teachers Design Instructional Modules ...... 29 Michael Forrest

Departments Writing: Photography: From the Directors: EarthScope ...... 2 Jill Andrews Mark Benthien Tales from the Front by Susan Hough ...... 9 Mark Benthien Michael Forrest News Briefs ...... 21 Thomas Henyey Sara Tekula Beneath the Science by Mark Benthien ...... 24 Susan Hough Off-Scale ...... 25 Scott Lindvall Assistant Editors: Calendar ...... 31 Thomas Rockwell Barbara Anderson Publications ...... 32 Sara Tekula Linda Townsdin SCEC Publication Order Form ...... 34 Subscription Info ...... 35 Column and Incidental Illustrations: Jim Hensley Cover: Computer enhanced trench log of Rose Canyon fault (see page 10)

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