Issues

One of the most battle-weary parameters in seismology today is stress drop. Seismologists argue over everything about this parameter, including its name, meaning, measurement, and scaling with magnitude.

The original concept of stress drop was introduced as a static measure of final fault slip, as a fraction of fault dimension (Δσ ∼ u/r), and was estimated from measurements or inferences of these geologically-based parameters (as, for example, by Kanamori and Anderson, BSSA, 1975, pp. 1,073–1,095). Stress drop became an important earthquake source parameter following Brune's classic paper (JGR, 1970, pp. 4,997–5,009), showing that the radiated far-field spectrum of shear waves could be interpreted in terms of a simple point-source model with just two source parameters—seismic moment (M₀) and stress drop (Δσ). This paved the way for measurments of stress drop from seismic signals. In Brune's model, the acceleration source spectrum has a simple `omega-squared' shape...

INTRODUCTION

Earthquakes are among the most deadly and expensive natural disasters affecting humankind. Exposure and vulnerability to the effects of earthquakes is increasing as urban centers grow, especially in tectonically active areas. Although all states within the US experience earthquakes, most seismicity occurs along the western margin plate boundary (including Alaska), the inter-mountain region (Basin and Range), the Mississippi embayment region, and the east coast. The economic and social effects of earthquakes can be reduced through a comprehensive assessment of seismic hazard and risk that leads to increased public awareness, seismically sensitive land-use planning, and the implementation of seismically sound building construction codes. Clear, well-documented assessments of seismic hazard are the first and fundamental step in the mitigation process.

With the recent and pending publications of the 1996 US National Seismic Hazard Maps (Frankel et al., 1996), the Southern California Earthquake Center Phase II (Working Group on California Earthquake Probabilities...

INTRODUCTION

This paper summarizes the nonparametric model for peak acceleration as a function of magnitude, distance, and site in Guerrero, Mexico that was prepared by Anderson and Lei (1994), hereafter referred to as AL94. The shallow part of this subduction zone dips at about 15 degrees, and in this way is similar to the Alaska and the Pacific Northwest (Cascadia) subduction zones in the United States. The largest earthquakes on the Mexican subduction thrust have had magnitudes of between 8.0 and 8.2. The data used in this study were obtained from the Guerrero accelerograph network (Anderson et al., 1994). The network was designed to record accelerograms from strong earthquakes on part of the Mexican subduction thrust. It is located in a mature seismic gap, and within the next few years it is likely to record one or more earthquakes with magnitude near 8. The sites in the Guerrero network were...

We present a new predictive relation for horizontal peak ground acceleration and 5% damped pseudo-velocity response spectrum appropriate for predicting earthquake ground motions in extensional tectonic regimes. This new empirical relation, which we denote “Sea96,” was originally derived by Spudich et al. (1996) as part of a project to estimate seismic hazard at the site of a proposed nuclear waste repository at Yucca Mountain, Nevada. Because of the length and relative inaccessibility of that report, we are briefly presenting the Sea96 relation and its derivation here.

We developed our relation based on data from extensional regime earthquakes having moment magnitude M > 5.0 recorded at distances less than 105 km. Extensional regions are regions in which the lithosphere is expanding areally. This areal expansion is the result of applied forces that yield a state of stress for which S_v > S_Hmax > S_Hmin, where S_v, S_Hmax, and S_Hmin represent principal...

Introduction

Since 1992, IRIS/IDA stations of the Global Seismographic Network have been configured as nodes on the Internet for the purpose of near realtime data access. The IDA Station Processor (ISP), a UNIX workstation connected to the IDA Data Acquisition System (IDAS), provides rapid data access to local and remote users. Additionally, it is used to monitor station state-of-health, and to unpack and copy data tapes for the station operators. The ISP may be installed at the same location as the IDAS or, should conditions require, at a different location connected via a dedicated telecommunication circuit. The software for real-time data collection and transfer, called the IDA Near Real Time System (NRTS), is designed to provide both continuous and occasional data telemetry from IRIS/IDA Stations to remote (from the station) users with the following goals in mind:

• To support real-time seismology

• To...

April 9–11, 1997 (Wednesday–Friday)
 Hawaiian Regent Hotel, Honolulu, Hawai'i, USA

For Current Information:

Via e-mail: [email protected]

Via WWW: http://www.soest.hawaii.edu/ssa97.html

Important Dates

Abstract Submission Deadline:January 7, 1997

Abstract Withdrawal Deadline:January 31, 1997

Program/Abstracts Available on WWW:February 14, 1997

Hotel Reservation Cutoff:March 7, 1997

Preregistration Deadline:March 14, 1997

Meeting Chairperson

Patricia A. Cooper
 Assoc. Prof. Geology & Geophysics/Asst. Dean, Graduate Division
 University of Hawai'i at Manoa
 2444 Dole St.
 Honolulu, HI 96822
 TEL: 808-956-6635
 FAX: 808-956-9797
 Email: [email protected]

EXHIBITS

Address inquiries to P. Cooper.

PROGRAM

Program Committee (Ed Berg, Gerard Fryer, and Neil Frazer) can be reached via email: [email protected]

Special Sessions

Wednesday, April 9, 1997, 8:30 AM–12:00 noon
 Earthquake Hazard and Risk Assessment
 Convener: Art Frankel
 e-mail: [email protected]

Wednesday, April 9, 1997, 8:30 AM–12:00 noon
 Comprehensive Test Ban Treaty Research
 Convener: Kevin Mayeda
 e-mail: [email protected]

Wednesday, April 9, 1997, 8:30 AM–12:00 noon
 Earthquake Seismology: Accomplishments and Challenges
 Convener: David Jackson
 e-mail: [email protected]

Wednesday, April...

The paper by Stump, Anderson and Pearson, “Physical constraints on mining explosions: Synergy of seismic and video data with three dimensional models” (SRL67(5):9–34) was an interesting and relevant article on the process of blasting, but though I (and later a colleague) searched, I could find no reference to the location of the mine (not in the text, nor on the figures; the paper does not contain any maps), the rock type, or the reason for the mining. The setting looks pretty bleak from the photos, so I presume it is not Florida—but where is it? I conclude that the omission of location is deliberate, given the care in specifying the “Sony, EVW-300 Hi-8” video camera.

While it may be that the authors consider the location of the mine irrelevant to the purpose of the paper (which is chiefly a “methods” paper), I've always been a great believer in the...

JAMES N. BRUNE TO RECEIVE SSA MEDAL

James N. Brune has been selected to receive the seventeenth Medal of the Seismological Society of America. The Medal will be awarded at the Society's Annual Luncheon, April 10, 1997, in Honolulu.

In support of the nomination of Brune for the Medal, John Anderson cited Brune's “uncanny ability to get to the basic physics of a problem, and advance our understanding of earthquakes...” His papers “touch on important problems in every area of seismology: surface waves, normal modes, source physics, rates of earthquake occurrences, seismic instrumentation, seismic site effects, and earthquake prediction.” His work provided a tool to link the observations on seismograms to the geological stresses driving the earthquake and encouraged the movement to digital recording. Other work formed the foundations for the use of “slip rates of faults...as an essential input to seismic hazard analysis.”

The Medal is awarded for outstanding...

New Post-Earthquake Investigation Guide

A newly revised field guide for post-earthquake investigations has been recently published by Earthquake Engineering Research Institute (EERI). This guide replaces the 1991 Earthquake Response Plan and Field Guide.

Over the years, the Field Guide has guided EERI reconnaissance team members in major earthquakes throughout the world. This latest version was revised to take into account research needs that have come to light in recent earthquakes in California and Japan. Although prepared primarily for EERI reconnaissance teams, the guide can be a useful tool for anyone involved in post-earthquake investigations. It emphasizes careful advance planning, outlines procedures for team coordination, describes responsibilities of project participants, and offers guidelines for specific data collection in the field. The guide covers a variety of subjects, from geosciences to engineering, emergency management, and social sciences. It contains various forms, international information sources, contact names, a pre-departure checklist, and recommendations for...

The 1995–96 Board of Directors of the Seismological Society of America met in the East Room of the Holiday Inn Convention Center, St. Louis on March 31, 1996. The meeting was called to order at 10:05 AM by President Steven G. Wesnousky. Present at roll call were Directors Archuleta, Campbell, Cormier, Schwartz, Wallace, and Wesnousky. Also present: Secretary Litehiser, Treasurer Followill, BSSA Editor Fehler, SRL Editor Ebel, Eastern Section Chair Christine PoweR, Directors-Elect Coppersmith, Malone, and Spudich, Executive Director Newman, and Assistant Director Rowe. The Secretary declared that a quorum of the Board was present. Joining the meeting in progress were Director Arabasz, Robert Herrmann, Chairman of the 1996 Annual Meeting and Patricia Cooper, Chairman of the 1997 Annual Meeting.

The Minutes of the Board of Directors meeting of March 21, 1995, were approved as printed in the November 1995 issue of Seismological Research Letters.

In the President's Report, Wesnousky...

During the Society fiscal year ending January 31, 1996, the SSA published Volume 85 of the Bulletin, comprising Numbers 1 through 6 and 1928 pages. During this fiscal year the Society also published Volume 66, Numbers 2 through 6 and Volume 67, Number 1, of Seismological Research Letters (SRL).

The Ninetieth Society Annual Meeting was held March 22–25, 1995, in E1 Paso, Texas. The Minutes of the meeting have been printed on page 99 of SRL, Volume 66, Number 6. The complete program of the meeting was published in SRL, Volume 66, Number 2.

Susan Newman, Society Director, Kathy Rowe, Assistant Director, and Linda Turnowski, Publications Production Editor and Marketing Assistant, continued to conduct the essential daily business of the Society from offices at 201 Plaza Professional Building, El Cerrito, California. They were assisted during seasonal peak periods by Dorothy Goldman, Membership Clerk.

The staff continued distribution of software developed...

Table of Contents

Accountants' Report on Financial Statements........ 243

Statement of Assets, Liabilities and Fund Balances..... 244

Statement of Revenues, Expenses and Changes in Fund Balances........................... 245

Statement of Cash Flows........................ 246

Notes to Financial Statements.................... 247

Supplementary Information

Schedule of Revenues....................... 249

Schedule of Expenses....................... 250

To the Board of Directors
 The Seismological Society of America

We have audited the accompanying statement of assets, liabilities and fund balances of The Seismological Society of America as of January 31, 1996 and 1995, and the related statements of revenues, expenses and changes in fund balances and cash flows for the years then ended. These financial statements are the responsibility of the Society's management. Our responsibility is to express an opinion on these financial statements based on our audits.

We conducted our audits in accordance with generally accepted auditing standards. Those standards require that we plan and perform the audit to obtain reasonable...

1997

January 30–February 1, Symposium in Honor of Vitelmo Bertero, Berkeley, CA.
 Sponsors: University of California, Berkeley, Earthquake Engineering Research Center; California Universities for Research in Earthquake Engineering. EERC-CUREe Bertero Symposium, EERC, 1301 S. 46th Street, Richmond CA 94804-4698; telephone 510-231-9554; fax 510-210-9471; e-mail [email protected].

February 3–5. Karlsruhe Workshop on Amplitude Preserving Seismic Reflection Imaging, Seeheim, Germany.
 E-mail [email protected]

February 23–27. ASEG-SEG 12th Annual Geophysical Conference and Exhibition, Sydney, Australia.
 Society of Exploration Geophysics.

April 9–11. Seismological Society of America's 92nd Annual Meeting, Honolulu, Hawaii, USA.
 Patricia Cooper, University of Hawaii at Manoa; phone 808-956-4254; fax 808-956-7346; e-mail [email protected]

April 13–16. NATO Advanced Research Workshop: Upper Mantle Heterogeneitics from Active and Passive Seismology, Moscow, Russia.
 Prof. K. Fuchs, Geophysical Institute, Hertzstr. 16, D-76187 Karlsruhe, Germany; fax +49 721 71173; e-mail [email protected]

April 17–19. EUROPROBE Conference on “Earth's Upper Mantle Structure Based on Integrated Geological and Geophysical Studies,”...