Issues

In October 1997, the U.S. Congress charged the Director of the U.S. Geological Survey to “provide for an assessment of regional seismic monitoring networks in the United States” under Public Law 105-47. While a report is being duly prepared by the USGS, with broad input from the seismological community, some critics may ask, “Do regional seismic networks (RSN's) really have a future? Or are they just a dying branch on the evolutionary tree of observational seismology? Should they functionally be superseded, say, by a combination of widely spaced, super-quality broadband stations and temporary dense arrays? Or organizationally by a national information outlet?” (Few, if any, would seriously apply these questions to California, but bear with me as I attempt a national overview.)

I believe that RSN's are vital elements both for building a next-generation national seismic system and for directly serving the 75 million people, including 46 million outside of...

INTRODUCTION

The Hayward Fault produced its last major (M7) earthquake in 1868 (Figure 1). It is widely considered to be the most hazardous fault in the San Francisco Bay region. In large part, this is because it lies so close to a densely populated urban corridor that has an abundance of old structures highly vulnerable to seismic hazard. The probability of a major earthquake on this fault was estimated to be 45% in thirty years (Working Group on California Earthquake Probabilities, 1990). In 1991, Lienkaemper et al. (hereinafter referred to as L91) estimated the potential for seismic slip along the entire length and depth of the fault zone. Recent studies have provided new information relevant to the seismic potential of the fault, which results in markedly larger estimates of its present potential for producing major earthquakes. Here we define the seismic potential as the total seismic moment on all parts...

INTRODUCTION

Reports of unusually intense ground motions in the very near fields of faults that have ruptured during earthquakes are becoming more common, particularly with the markedly increased worldwide strong-motion instrumentation in recent years (e.g., Heaton and Wald, 1994). The reported ground motions are sufficiently strong to have significant potential engineering impact (Hall et al., 1995). In addition to fault proximity, two other factors that have contributed to unusually high strong motions are rupture directivity (e.g., Somerville et al., 1997) and locations on the hanging walls of thrust faults (e.g., Nason, 1973; Abrahamson and Somerville, 1996; Brune, 1996a; Brune, 1996b). Perhaps nowhere has the sharp distinction between damage on the hanging wall and footwall of a thrust fault been more dramatically documented than during the 1945 Mikawa earthquake, Japan (Iida, 1985). Earlier reports of anomalous strong near-field vertical acceleration, such as those of Oldham (1899) describing the great 1897 Assam...

INTRODUCTION

The Pasadena Office of the U.S. Geological Survey (USGS), together with the Caltech Seismology Laboratory, operates a network of more than 350 remote seismometers in southern California called the Southern California Seismic Network (SCSN). The SCSN is part of TriNet, a cooperative project between the USGS, Caltech, and the California Division of Mines and Geology (CDMG). TriNet will upgrade the existing network to digital recording, add new stations, and develop real-time and early-warning capabilities. Signals from the SCSN sites are telemetered to a central processing location at the Caltech Seismology Lab in Pasadena. These signals are continuously monitored by computers that detect and record thousands of earthquakes each year. Phase arrival times for these events are picked by analysts and archived along with digital seismograms. Data acquisition, processing, and archiving are achieved using the Caltech/USGS Seismic Processing (CUSP) system (Dollar, 1989). These data have been compiled into the SCSN...

HURRICANE SEASON

People are fascinated by both earthquakes and the weather, hence there is a natural tendency to seek correlations between these two dynamic expressions of the Earth. On a recent trip to California, a well informed friend asked me about “earthquake weather.” I had to confess that I was not very knowledgeable about this phenomenon, so my friend proceeded to tell me about it so that even I could forecast earthquakes. I tried to convince my friend that there is relatively little energy transferred from the fluid to the solid part of the Earth, but then a rather embarrassing question surfaced: How much energy do you need to trigger an earthquake? Needless to say, my friend still believes in earthquake weather.

There is one phenomenon where seismologists readily acknowledge the influence of the fluid Earth upon our seismograms: noise. Yes, the wind that shakes the trees and buildings makes...

INTRODUCTION

The National Earthquake Hazard Program of the Geological Survey of Canada (GSC) has made extensive use of the Internet to disseminate information regarding its programs. Our Web site has been the recipient of much positive feedback from public and government agencies alike, and enjoys a high profile within the internet community. Interested parties may access this site at http://www.seismo.nrcan.gc.ca.

It is a natural step, therefore, to use this visibility to collect information from the public regarding felt effects of a large earthquake. With this as a goal, we experimented in a very limited way with two small earthquakes. The first occurred on June 24, 1997 in Georgia Strait, offthe coast of British Columbia. With a magnitude of 4.6, the event was felt in the interior of the province to a distance of 150 km. In total we collected just over 100 replies and produced an isoseismal map for internal...

This report includes hypocenters for seismic events that occurred in January and February 1997 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 a magnitude 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 PDE Monthly Listing. All reported intensities correspond to the Modified Mercalli Intensity Scale or other closely related...

GRANT OPPORTUNITY FOR SCIENCE/ENGINEERING GRADUATE STUDENTS

“Summer Programs in Japan and Korea”, sponsored by the National Science Foundation (NSF), National Institutes of Health (NIH), and U.S. Department of Agriculture (USDA), aims to provide U.S. graduate students first-hand experience in a Japanese or Korean research environment, intensive Japanese/Korean language training, and an introduction to the science and science-policy infrastructure of Japan/Korea. Required fields of study are science or engineering, including biomedical and agricultural sciences. Applicants must be U.S. citizens or permanent residents, be enrolled at a U.S. institution in a relevant Ph.D., M.D., or M.S. program of which at least one year has been completed, and be pursuing studies in fields of science or engineering that are supported by NSF, NIH, or USDA. Program dates for Japan are late June to late August; for Korea, mid-June to early August. Awards are for travel costs to and from Japan/Korea, living costs while...

S-13J RELEASED BY TELEDYNE BROWN ENGINEERING

A new Geotech short-period seismometer has met all of its production and final acceptance testing and is now ready for delivery. The S-13J is a 1 Hz moving coil velocity transducer ideal for portable applications which require exceptional performance in a small size. Weighing only 3 kg, its height and diameter are 18.5 and 10.2 cm, respectively. It is available in a vertical or horizontal version and operates in a broad range of temperatures (–51°C to +60°C).

Featuring adjustable mass position and free period, mass lock and built-in calibration coil, the new seismometer inherited the design and the stability of its predecessor, the time-proven Model S-13. This design ensures that adjustments are seldom required and maintenance in the field is very simple.

When operated in an overdamped mode, a medium to broadband system is achieved, with a noise below the Low Noise Model for...

Seismotectonic Maps of the Wabash Valley Seismic Zone

A folio of new seismotectonic maps of the Wabash Valley seismic zone (WVSZ) in Illinois, Indiana, and Kentucky is available for purchase. The full color, 1:250,000-scale maps are all on the same base. They show a seismically active area northeast of the New Madrid Seismic Zone, which is itself shown in a previously published series of seismotectonic maps (SRL 66:3 [1995], p. 39 and 67:2 [1996], p. 13). The new maps of the WVSZ span latitudes 36.50°–39°N and longitudes 87°–89°W. The maps were produced by a collaboration between the U.S. Geological Survey and the Illinois Basin Consortium (IBC: Illinois State, Indiana, and Kentucky Geological Surveys). The first four maps in the folio are published as USGS Geologic Investigations Series Maps I-2583-A through -D, and the last two maps are published by the IBC as Illinois State Geological Survey (ISGS) open file maps...

SEISMOLOGICAL SOCIETY OF AMERICA 94th ANNUAL MEETING

May 3–5, 1998 (Monday–Wednesday)

Northwest Rooms, Seattle Center Seattle, Washington, USA

For Current Information:

Via WWW: http://www.geophys.washington.edu/SEIS/SSA99/ Email: [email protected]

Geology Conference Room, Benson Earth Sciences Building, University of Colorado, Boulder, Colorado

March 15, 1998

The 1997–98 Board of Directors of the Seismological Society of America met in the Geology Conference Room of the Benson Earth Sciences Building on the Campus of the University of Colorado on March 15, 1998. The meeting was called to order at 9:40 am by President Ralph J. Archuleta. Present at roll call were Directors Ammon, Atkinson, Coppersmith, Cormier, Harris, Malone, Schwartz, Spudich, and Wallace. Also present: Secretary Litehiser, Treasurer Followill, Bulletin Editor Fehler, Seismological Research Letters Editor Ebel, Director-Elect Hough, Director-Elect Somerville, Executive Director Newman, and Assistant Director Rowe. The Secretary declared that a quorum of the Board was present. Joining the meeting in progress were Anne Sheehan, cochairman of the 1998 Annual Meeting, Tom Reed, government affairs consultant, Chris Biemesderfer, electronic publishing consultant, and Kim Olsen, Web Page Editor.

The Minutes of the...

1998

November 25–27. 10th Japan Earthquake Engineering Symposium (JEES), Yokohama, Japan.

Sponsored by the Earthquake Engineering Research Liaison Committee, Science Council of Japan, and organized by the Architectural Institute of Japan, Association for Earthquake Disaster Prevention, Japan Geotechnical Society, Japan Society of Civil Engineers, and others, this symposium will present the most recent research on the 1995 Kyogo-ken Nambu (Kobe) earthquake, including its effects and resultant disaster mitigation initiatives. 10th JEES, c/o Architectural Institute of Japan, 26-20 Shiga, 5-chome, Minato-ku, Tokyo, 108 Japan; telephone 81-3-3456-2051; fax 81-3-3456-2058; URL http://www.aij.or.jp/jees/index.html.

November 30–December 3. 1998 Joint Conference of the Geological Society of New Zealand and the New Zealand Geophysical Society, University of Canterbury, Christchurch, New Zealand.

The main topic of the conference is a symposium on “The South Island Plate Boundary.” Conference circular and registration form are at http://www.gsnz.org.nz. For more information, e-mail [email protected].

December 1–3. ESG1998, Yokohama City, Japan.

The Second International Symposium...