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The following is based on my “parting comments” made at the annual meeting of the Council of the National Seismic System (CNSS) in May of this year. These comments originate from my experiences over the last two years as Chairman of the CNSS and reflect some of the frustrations I experienced as well as recognition of progress made and my hopes for the future. While they are mostly for the benefit of seismic network operators and staff, they may be of interest to anyone concerned about the future of long-term seismic monitoring in the U.S.

First, as Vice-chairman and then Chairman of the CNSS, I learned a lot about the complex aspects of cooperation between networks and the coordination needed to serve our many clients effectively. I gained a new appreciation of many individuals who take responsibility for making things work on a scale larger than a single network. Unfortunately,...

Seismological Research Letters September 01, 1999, Vol.70, 475-477. doi:


Large intermediate-depth, normal-faulting earthquakes in the subducted Cocos plate result in significant damage to the cities and the villages of the Mexican altiplano. Some examples are the earthquake of January 15, 1931 (M 7.8), which caused heavy damage to the city of Oaxaca (Barrera, 1931; Singh et al., 1985); and the earthquakes of August 28, 1973 (Mw 7.0) and October 24, 1980 (Mw 7.0), which resulted in deaths and damages in the states of Veracruz, Puebla, and Oaxaca (Singh and Wyss, 1976; Yamamoto et al., 1984). It has been suggested that the great earthquake of June 19, 1858, which caused severe damage to inland towns in the state of Michoacáin, including its capital city of Morelia, and to México City may also have been an intermediate-depth, normal-faulting event (Singh et al., 1996). Such earthquakes (M## 6.5), which have occurred in the states of Oaxaca, Veracruz, and Puebla, are shown...

Seismological Research Letters September 01, 1999, Vol.70, 489-504. doi:


Lahars from Mt. Ruapehu's Crater Lake pose the greatest volcanic risk to mountain users. Recent large eruptions occurred in 1945, 1969, 1975, 1981, 1988, and 1995-96, and all generated lahars (Gregg, 1960; Houghton et al., 1987). There are three ski fields on the upper slopes of Mt. Ruapehu (Figure 1), and lahars originating from the summit crater lake, which travel at speeds of up to 20 m/s, can reach the upper ski fields within 90 seconds (Ruapehu Surveillance Group, 1996). In addition, the summit area is a popular destination for hikers and climbers. Anyone caught in the path of a lahar is likely to be injured or killed. Consequently, it is of utmost importance to detect eruptions that are likely to generate lahars and to trigger warning systems on the mountain in near real-time. In contrast, the risk of injury from the eruption of large rocks is confined to...

Seismological Research Letters September 01, 1999, Vol.70, 505-511. doi:


On the morning of 7 August 1998 terrorists detonated truck bombs nearly simultaneously at American embassies in Nairobi, Kenya and Dar es Salaam, Tanzania. In both cases the terrorists were unable to penetrate embassy security measures completely; however, the blasts were large enough that irreparable damage was done to the two chanceries, and several nearby vehicles and structures were completely destroyed. Though the U.S. embassy in Nairobi was left standing (Figure 1), the nearby Ufundi building was totally demolished, resulting in significant loss of life. Others were maimed and killed by glass fragments ejected from embassy windows and the windows of the neighboring Cooperative Bank House. More than 4,000 persons were wounded in the attacks, and at least 220 were killed (Crowe et al., 1998).

The Nairobi attack was recorded by a three-component, broadband seismometer (NAI) operated by the Geology Department of the University of Nairobi (Hollnack and Schliiter,...

Seismological Research Letters September 01, 1999, Vol.70, 512-521. doi:


More than 3,000 digital seismic stations are operated around the world, many of them with communication capability. Currently only a few subsets of these stations can operate automatically as networks performing event detection and data retrieval, since no standard has been defined for linking them together. Clearly, if this was generally possible, new options for seismic networks would become available. The purpose of this paper is to define a virtual seismic network, which links together seismic stations with communication capabilities, to set up the design concept for the network software, and to describe the initial implementation of such a system.

There are two ways of recording data from seismic sensors: (A) the data stream is transferred continuously and recorded at a central acquisition system, and (B) the data are recorded on a local data acquisition system in the field and have to be transferred to the central site at...

Seismological Research Letters September 01, 1999, Vol.70, 522-528. doi:

I believe that all of us are acutely aware of the information overload that swamps our professional lives. Each of us will return to our home institutions and find 50-100 e-mail messages (maybe more) and a mail box stuffed with all kinds of announcements, letters, junk mail, and our own scientific journals (at least electrons are an inexhaustible supply, while trees are not). The overall issue of information overload is too large a subject for me to tackle. (God knows you would all be fleeing for the exits if I were to try.) I want to confine my thoughts to an issue that affects us all as scientific scholars: How do we communicate our own ideas while giving proper credit to our colleagues?

I won't speak for anyone but myself, though I suspect many have had similar experiences. Now and then I find an hour or so where I can...

Seismological Research Letters September 01, 1999, Vol.70, 530-531. doi:

In seismology, a wealth of data-processing programs are available, and a seismic observatory typically makes use of several. A common problem is the lack of a proper database structure which prevents effective use of the data, particularly with data from different sources. A primary goal of SeisAn is to organize data from all kinds of seismic stations into a simple database and to provide most of the tools needed for routine processing. The SeisAn database is a way of organizing data by using the directory and file structure, and is not a relational data system with general access techniques such as SQL, which usually is meant by the term “database.” In addition, the intention is to facilitate research tasks by integrating additional programs to work directly on the database.

A second goal is that SeisAn must work in an identical manner under Sun (Solaris-1 and -2), Linux, and MS-Windows, and...

Seismological Research Letters September 01, 1999, Vol.70, 532-534. doi:

It's summer. You are sitting outside, enjoying the sights, sounds, and hot sun. You begin to wonder why the sun's rays seem to be focused on you. As you sit up straight and look around, the bright reflection off a nearby metal sculpture blinds you, the adjacent greenhouse glares at you, and you catch a flash from a high-flying jet. Now you're bothered enough to shift to a different location, but oddly enough you still seem to be at a focal point. Now you realize that you are really sweating, so you decide to go inside where you can more safely contemplate the dazzling effects of focusing. While cooling down, why not write some fun educational software or problem sets and send it to us at EduQuakes!

One of my favorite seismological programs is Seismic Waves, written by Alan Jones at SUNY Binghamton and made available for download through his...

Seismological Research Letters September 01, 1999, Vol.70, 535-536. doi:
Seismological Research Letters September 01, 1999, Vol.70, 554-576. doi:
Seismological Research Letters September 01, 1999, Vol.70, 577-595. doi:

This report includes hypocenters for seismic events that occurred in March and April 1998 as published in the Preliminary Determination of Epicenters (PDE) Monthly Listing, U.S. Geological Survey, National Earthquake Information Center. It is limited to three types of events: (1) earthquakes with magnitudes of 6.0 or greater, (2) earthquakes causing substantial damage, and (3) events of special interest.

Time is given in Coordinated Universal Time (UTC) unless otherwise specified. Latitude and longitude are given to hundredths of a degree for all locations except for events at the Nevada Test Site, which are given to hundredths of a second of arc. Depths constrained to “normal” (33 km) or other assigned depths are indicated by “constrained.” Depths determined from depth phases are marked “depth phases.” Reports followed by (GS) are taken from the POE Monthly Listing. All reported intensities correspond to the Modified Mercalli Intensity Scale or other closely related 12-point...

Seismological Research Letters September 01, 1999, Vol.70, 597-602. doi:


In the March/April 1999 SRL we were very interested to read the ES column on Network Recording Systems. We have a bone to pick. The column completely neglected systems from outside the U.S. It states that the “ANZA network in the 1980's was the first regional network to be totally digital.” This isn't true. The Gräfenberg Array (GRF) in Germany was/is the first totally digital network with local digitizers and digital communications links. It has been operating and collecting data continuously since 1975. Back then, as now, the network ran using acquisition and telemetry software specially developed for it, along with analysis software that was designed specifically to use the array capabilities. In the nearly twenty-five years since it went on-line, GRF has regularly upgraded the recording medium, the digitizer circuits, and the analysis software. The only thing remaining the same are the STS-1 seismometers, which have been in use...

Seismological Research Letters September 01, 1999, Vol.70, 478. doi:

News & Notes


In an effort to inform the seismological community about the comings and goings of SSA members, SRL is soliciting news items about personnel changes and promotions in universities, research centers, government agencies, and private industry. The kinds of items we would like to receive include announcements of promotions, such as new directors of research institutes, branch chiefs or office chiefs, department chairmen, tenured faculty, etc.; hiring of new institute, laboratory, or research directors; hiring of new faculty members and research scientists; retirements; job changes of individuals; government or company reorganizations; and awards and honors. These items will be included as part of a new section of SRL called “Transitions” (see page 487). Please mail, e-mail, or telephone your items to John E. Ebel, Weston Observatory, Boston College, 381 Concord Road, Weston, MA 02493, USA; telephone (617) 552-8300; e-mail



Seismological Research Letters September 01, 1999, Vol.70, 479-486. doi:



SSA member Kerry E. Sieh has been chosen for membership in the National Academy of Sciences. NAS recognized his achievements in original research. Sieh is currently Professor of Geological Sciences, California Institute of Technology, Pasadena, California.


SSA member J. Freeman Gilbert (Institute of Geophysics and Planetary Physics, University of California at San Diego) was awarded the William Bowie Medal at the American Geophysical Union Spring Meeting Honors Ceremony held on June 2, 1999 in Boston, Massachusetts. The medal recognizes outstanding contributions to fundamental geophysics and unselfish cooperation in research. The citation included references to his pioneering work at MIT, where he used the Whirlwind computer to apply computational methods to seismic problems; his work on the computation of synthetic seismograms in simple media; the moment tensor description of the seismic source that revolutionized the way earthquakes are analyzed; and development...

Seismological Research Letters September 01, 1999, Vol.70, 487. doi:


SSA Press Releases

The Society has actively sought press coverage of the annual meetings for several years. Late in 1998, we decided to start bringing newsworthy articles in the Bulletin and SRLto the attention of the press. Our goal is to increase the visibility of these publications both among the research community and the general public. We hope that the increased visibility will lead to more groundbreaking research being published in the Bulletin.

We want to take this opportunity to explain some of the criteria that go into deciding when to issue a press release. Papers are initially identified by our press relations consultant, Nancy Sauer. She explains, “A major finding with implications for public safety is always a good bet, at least in the affected region. Basic science and structural studies can be of interest if they are somewhat revolutionary or challenge the conventional wisdom. Unfortunately, I have to...

Seismological Research Letters September 01, 1999, Vol.70, 488. doi:


Figure 7 (page 318) has several incorrectly included or omitted estimates of mb completeness thresholds for the 1995 ISC Bulletin. Since fewer than 100 mb values were available for shallow earthquakes, no threshold should have been given for Regions 13, 25, and 46. Since more than 100 mb values were available for shallow earthquakes, the thresholds in Table 1 should have been given for Regions 32, 41, and 43.

Figure 8 (page 318) has inaccurately shown threshold estimates for Regions 14 and 24, which should have been shown as 4.5 for each. In addition, Region 48 should have been excluded from Figure 8, since fewer than 100 mb values were available in this region for 1994.

In all cases, Table 1 shows an accurate estimate of mb threshold if and only if at least 100 mb values were available for shallow earthquakes during a calendar year. The frequency/magnitude plots used...

Seismological Research Letters September 01, 1999, Vol.70, 529. doi:

Book review

Most texts on seismology appear to regard the free oscillations of the Earth as a Byzantine backwater which is best avoided if at all possible or otherwise relegated to a single chapter near the back of the book. In my completely unbiased view, this is a mistake. Much of the modern theoretical basis for interpreting waveforms in global seismology is built upon mode theory, and for good reason-any attempts to generalize ray-based approximations rapidly become very tangled.

In this respect, Dahlen and Tromp are like a breath of fresh air. The authors take an unabashedly modal view of theoretical seismology. Furthermore, they start at the beginning of the subject-a careful discussion of the underlying continuum mechanics-and build from there. In fact, the first one third of the book (after an entertaining historical introduction) is devoted to “fundamentals.” The authors describe this part of the book as having the longest “shelf...

Seismological Research Letters September 01, 1999, Vol.70, 537. doi:


NEES 1998 Workshop: Final Report. In May 1998 a workshop for in-depth discussion of the technical and cultural issues related to the formation of the National Network for Earthquake Engineering Simulation (NEES) was held at the University of California, Davis (UCD). The workshop involved the geotechnical earthquake engineering research community as well as representatives from the structural, seismological, and coastal earthquake engineering disciplines. Among the topics discussed were efficient use of networked experimental facilities for earthquake engineering problem-solving, including the issues of intellectual property rights, data-sharing protocols, instrumentation technology, and outreach. The final report for this workshop is now available. The complete citation for the report is Geotechnical Earthquake Engineering Experimental Facilities: Developing a National Network with Structural, Seismological, and Coastal Earthquake Engineering Seismic Simulation Facilities (Report No. UCD/CGM-99/01), B. L. Kutter, R. Dobry, F. Raichlen, N. Sitar, K. H. Stoke, and L. T. Youd, steering committee. Final report on...

Seismological Research Letters September 01, 1999, Vol.70, 538-540. doi:


The following are statements from candidates seeking election to the SSA Board of Directors. Ballots and other election information will be sent to SSA members in the fall.

Clarence Allen

Seismological Laboratory, Caltech, Pasadena, California

Principal fields: Seismotectonics, geology of earthquakes, seismic-hazard assessment

Over its history, the SSA has had two major activities: scientific publications and scientific meetings. We have an outstanding record in these limited and focused activities, and I think we should continue to concentrate our efforts there and not try to become everything to everyone. New activities may well be justified, but we should scrutinize them carefully to make sure that they are within our mandate, our capabilities, and our budget. Both our publications and our meetings, of course, have had very significant improvements over the years, and hopefully forward-looking changes will continue. A particular challenge over the next few years will be dealing with the opportunities...

Seismological Research Letters September 01, 1999, Vol.70, 541-543. doi:


The 94th Annual Meeting of the Seismological Society of America was held on May 2-5, 1999, in the Northwest Rooms at the Seattle Center. The same rooms had also been used for SSA meetings in 1964 and 1980. Similar to the situation for these two previous meetings, which either caused or were associated with major geophysical events (1964 Alaska earthquake and 1980 eruption of Mount St. Helens), the 1999 SSA meeting occurred in association with relatively good weather for three days in May, a geophysical/meteorological event of some note in Seattle.

The meeting was hosted by the University of Washington Geophysics Program. Steve Malone chaired the meeting and Ruth Ludwin coordinated logistical arrangements. Approximately 300 posters and papers, divided into thirty technical sessions, were presented during the three-day meeting, which drew 388 participants. The annual meeting of the Council of the National Seismic System followed the SSA meeting on the...

Seismological Research Letters September 01, 1999, Vol.70, 544-549. doi:


Seismological Society of America 95th Annual Meeting

April 10-12, 2000 (Monday-Wednesday) Hanalei Hotel, San Diego, California, USA

Hosted by: Cecil H. and Ida M. Green Institute of Geophysics and Planetary Physics (IGPP) Scripps Institution of Oceanography (SIO) University of California at San Diego (UCSD)

Seismological Research Letters September 01, 1999, Vol.70, 550-553. doi:


71st Annual Meeting of the Eastern Section Seismological Society of America


Site: Adam's Mark Hotel, Memphis Tennessee

Dates: October 16-17, 1999: Field Trip, leaving early evening of October 16. October 18-20, 1999: Technical Sessions, ending noon of October 20.

Seismological Research Letters September 01, 1999, Vol.70, 596. doi:



September 22-24. Practical Seismic Design for New and Existing Structures, London, England, UK.

This short course will be presented by the Engineering Seismology and Earthquake Engineering (ESEE) Section of the Department of Civil and Environmental Engineering at Imperial College, in collaboration with the Society of Earthquake and Civil Engineering Dynamics (SECED) and under the auspices of the European Association for Earthquake Engineering (EAEE). Dr. Julian Bommer, Course Chairman, Department of Civil and Environmental Engineering, Imperial College, London SW7 2BU, UK; telephone 0171-594-5984; fax 0171-225-2716; e-mail To register contact Sally Varkaik, Imperial College, Centre for Continuing Education, Sherfield Building, Exhibition Road, London SW7 2AZ, UK; telephone 0171-594-6882; fax 0171-594-6883; e-mail

September 22-26. International Symposium in Earthquake Engineering (ISEE '99), Budva, Montenegro, Yugoslavia.

Supported by the International Association of Earthquake Engineering and by the United Nations Development Program. The objective of ISEE '99 is to promote scientific and technical...

Seismological Research Letters September 01, 1999, Vol.70, 603-606. doi:
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