next up previous contents
Next: Operations Up: Introduction Previous: Director's Report   Contents
Home: Berkeley Seismological Laboratory


In Memoriam - Thomas V. McEvilly

Subsections

Figure 2.1: Tom McEvilly (1934-2002). Photograph courtesy of Lawrence Berkeley National Laboratory.
\begin{figure*}\begin{center}
\epsfig{file=tom.eps,width=11cm}\end{center}\end{figure*}

Introduction

Thomas Vincent McEvilly died on February 22, 2002. Tom was a valuable member of the Berkeley Seismological Laboratory and the Department of Earth and Planetary Science.

Tom contributed to the BSL in many ways - through important seismological research, through the development of several seismological networks and observational practices, and through service as Assistant Director from 1968 to 1989 and several stints as Acting Director (most recently from February 1 to May 31, 2001). His leadership in the development of the Parkfield High Resolution Seismic Network, the Hayward Fault Network, and Mini-Plate Boundary Observatory was critical to the success of these projects and his influence continues in these efforts today.

Tom's many achievements have been remembered in obituaries written by Lane Johnson for the Seismological Society of America (Johnson, 2002) and Bruce Bolt for the American Geophysical Union (Bolt, 2002).

A Web site has been established where photographs, press releases, and testimonials are available at http://seismo.berkeley.edu/news/tom_mcevilly.html.

McEvilly Graduate Student Fellowship in Seismology

To preserve his memory, Tom's family has requested that the Department of Earth and Planetary Science establish the McEvilly Graduate Student Fellowship in Seismology. Contributions toward the McEvilly Graduate Student Fellowship should be made out to "The Regents of the University of California" and addressed to Susan Torrano, Department of Earth and Planetary Science, 307 McCone Hall, University of California, Berkeley, CA, 94720-4767.

A Celebration Of Tom McEvilly's Life

Tom's contributions to the BSL, the Department, to seismology, and to his friends and family were celebrated in a memorial service at UC Berkeley on April 22 in the Faculty Club. Ian Carmichael, Barbara Romanowicz, Ernie Majer, Jim Hannon, and Steve McEvilly offered remembrances during the ceremony. Many members of the community shared stories and memories.

The following is a transcript of the address given by Barbara Romanowicz during the service.

Tom McEvilly's career as a seismologist

It is rather hard to summarize in a few minutes Tom's lifetime contributions to Seismology, especially as I was only entering high school and had no clue that there was such a field as Seismology, when Tom was joining the ranks of Ph.D.'s at St Louis University.

So, I decided to give it a personal perspective, and I would like his numerous students and collaborators who are here today to excuse me if I omit some important aspect of Tom's work.

I first became aware of Tom's scientific existence around 1981-82, when, as a post-doc, I was studying surface wave dispersion across Tibet, to remotely unravel the crust and lithospheric structure of that unique area of the world. Tom's early work, indeed his Ph.D. topic, was on the study of crustal structure through the inversion of Love and Rayleigh wave phase velocities under the central US. In this work, which he published in BSSA at the end of 1964, he found that, in this region, he couldn't fit Love and Rayleigh waves with a unique model, implying the existence of anisotropy in the upper mantle under the continent. Well, these were the pioneering days of such studies, but they remain quite current even as I speak. For me this was particularly striking at the time (that is in the early 1980's), as, for whatever it is worth now, I was able to find a single model to fit Love and Rayleigh wave dispersion data across Tibet.

After he came to Berkeley, Tom's work naturally turned to the regional earthquake problem, progressively adding and I will say lots more about that, but since I mentioned my work on Tibet, published in 1982 - it turns out Tom also got interested in Tibet structure as seen by surface waves at about the same time as I did, and with student Kin-Yip Chun proposed, in addition to the very unusual 70 km thick crust, the existence of a mid-crustal low velocity zone in Tibet, an intriguing result from the point of view of rheology and dynamics. Because this work was done in parallel with mine, and I was in France at that time, somehow I only became aware of it much later on, when I came to work at Berkeley.

I first met Tom in person when he became the first president of the IRIS Consortium in 1984. I may have met him earlier, but that's the time I really first paid attention. I still remember having been struck by his cheerful style presiding the IRIS meeting at the Fall San Francisco AGU that year.

So, anyway, back to Tom's career at UC Berkeley since the mid-60's. Several main themes prevail: an interest in seismic instrumentation, which dates back to his involvement with the seismic instrument manufacturer Spregnether, amplified by his participation in regional network issues at the Berkeley Seismographic Station. Tom turned into one of the best experts in seismic instrumentation in the country - in 1982, as a member of the NAS Committee on Seismology, he chaired an NRC panel and report on seismic networks which resulted in his involvement in the IRIS program from its very beginning. I emphasize this here, because circumstances have it that almost 20 years later, we are holding today and tomorrow, a session of the Executive Committee of IRIS here at Berkeley, and I have asked Dave Simpson, the IRIS president, to later comment specifically on Tom's contribution through IRIS to the seismological community.

For those of you who are not familiar with this program, IRIS stands for Incorporated Research Institutions for Seismology, and is an NSF funded consortium devoted to the development of infrastructure for seismology. Its main 3 components are the Global Seismic Network, a network of 120 seismic stations distributed globally contributing data for the study of the deep structure of the Earth at the global scale, the PASSCAL program, a pool of portable seismic instruments for regional deployments, and a Data Management System to collect, archive and distribute the IRIS data.

The second theme of Tom's research career, has to do with various aspects of applied seismology: involvement in CTBT related research, monitoring of the Geysers geothermal area, and various other studies which he conducted in collaboration with colleagues at Lawrence Berkeley National Laboratory. I will let Ernie Majer comment on those contributions.

The third theme, and one on which I would like to now expand on, is the study of earthquake processes based on observations on the San Andreas system in California. It doesn't take much to figure out that this main direction of Tom's research was profoundly influenced by the 1966 Parkfield earthquake, which occurred shortly after Tom first came to Berkeley. Parkfield is a very small town (population about 20-some the last time I checked) about half way between San Francisco and Los Angeles, on the San Andreas Fault, which has become the focus of intense seismological interest after this 1966 earthquake, because it appeared to be the site of periodically recurring earthquakes of about magnitude 6, every 22 years on average, the 1966 being the last one of a series of 5 documented events. Parkfield also lies right at the boundary between a "locked zone" on the SAF, to the south, which last broke in the 1857 great Los Angeles (Fort Tejon) earthquake, and a "creeping zone" to the north, which slips steadily and may not have ever experienced a large earthquake.

Shortly after 1968, with students Bill Bakun and John Filson, Tom studied the 1966 Parkfield sequence, using surface wave data, which he was an expert on and later went on to study earthquake source processes with a variety of techniques, in particular near field recordings in the 1980's with Keith McLaughlin and Lane Johnson.

Perhaps more significantly, Tom was involved from the very beginning in the Parkfield earthquake prediction experiment which got off the ground in the early 1970's. Notable early contributions are a paper with Lane Johnson in Science in 1973 on the "dilatancy" issue (the change in the ratio of shear to compressional velocities before earthquakes), and his work using the synthetic VIBROSEIS source of shear wave vibrations, with which he produced a large dataset of consistent waveforms to study temporal changes in crustal properties in the vicinity of the San Andreas Fault, as they might relate to earthquakes - a topic which is still generating publications, most recently with Valeri Korneev at LBL and Eleni Karageorgi, now back in Greece. Tom also was an important mover in several other data acquisition programs using artificial sources to study crustal structure, such as CALCRUST in the 1980's, and more recently the BASIX experiment (1993) in the San Francisco Bay Area.

The real highlight of his career, however, emerged from his investment in the deployment of a then highly unique 10 station borehole seismic network at Parkfield, which started producing data in 1987. The idea was to install seismometers several hundred meters under the Earth's surface, to get away from the noise-generating near-surface weathered layers of rocks, and pick-up clear signals from tiny microearthquakes (down to magnitude M -1) that illuminate the fault zone and might reveal something on how the fault works at the microscopic scale. This proved worthwhile. The strong heterogeneity of structure in and around the fault zone turned out to be an issue: it blurred the view and preventing the earthquakes from being accurately located. With students Alberto Michelini and Bill Foxall, Tom first concentrated on resolving this complex structure through joint hypocentral and velocity inversions, unravelling strikingly organized heterogenity in the fault zone. The discovery of repeating earthquakes, clusters of tightly localized tiny earthquakes producing identical seismic waveforms and their systematic exploitation, through the development of an appropriate data mining methodology, with Bill Foxall and then graduate student Bob Nadeau, led to a series of papers of fundamental significance for earthquake physics. Based on 10 years of data from the borehole Parkfield network, Nadeau and McEvilly documented the quasi-periodic occurrence of micro-earthquakes within well identified clusters, and more recently showed the passage of a stress wave across the Parkfield area in the time period 1988-1995. As shown by Nadeau and Johnson (1998), the characteristics of the micro earthquake clusters has consequences on the distribution of strength and stress, as well as heat generation on the fault. Tom's illness caught him in the middle of finalizing most recent work, in which Nadeau and he documented intriguing pulses in slip rate on the San Andreas fault over distances of tens of kilometers.

To the very end, Tom kept a hands-on approach and wanted to have a chance to "look" at data and process them himself. Bob Nadeau specially travelled to Saint Louis to bring him his Sun workstation so he could work whenever he felt better. It is really too bad that Tom won't be around to glean all the fruits of his hard work at Parkfield, which are only starting to ripen.

Let me finally mention that the Parkfield borehole network has played and is still playing a critical role in the definition of the SAFOD experiment, the San Andreas Fault Observatory at Depth, which is part of the NSF Earthscope Major Research Equipment initiatives hopefully soon to be funded. Tom played a very active role in SAFOD and his absence will be felt.

Closer to home, I would like to finish on a more personal note: Tom's visits (he travelled a lot in recent years) were always like a ray of sunshine at the Berkeley Seismological Laboratory. He was very supportive of our efforts, and I particularly appreciated his advice on delicate diplomatic issues - with him, there was always an easy way out, he had the charm to always turn a confrontational issue into an easy solution - even though he would drive Eleanor, our MSO, crazy with his imaginative solutions to bureaucratic problems - I have lost one of a handful of friends that I could always rely on in my professional life.

References

Johnson, L., Thomas V. McEvilly, Seism. Res. Lett., 73. 455-456, 2002.

Bolt, B., Thomas Vincent McEvilly, EOS, Trans. AGU, 83. 311, 2002.



next up previous contents
Berkeley Seismological Laboratory
215 McCone Hall, UC Berkeley, Berkeley, CA 94 720-4760
Questions or comments? Send e-mail: www@seismo.berkeley.edu
© 2002, The Regents of the University of California.