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Issues

The inaugural issue of the “New SRL” includes an interesting and thought-provoking montage of information that stirs several interesting thoughts. The issue begins with John Ebel's opinion: “As someone who interfaces regularly with the public on earthquake issues, I see the importance of this kind of journal for the good of seismology as a whole. The public wants information about earthquakes, and interesting earthquake information or research results can motivate elements of society to take measures to mitigate the effects of future earthquakes.”

Recent activity at NOAA's National Geophysical Data Center suggests a change in our interactions with the public. During 1992 we had roughly 23,600 data and information requests, all off-line. Our ftp server opened during December, 1992 and served 324 on-line requests. Our off-line requests for 1995 will be roughly 28,500, up 20% from 1992. Our on-line requests for 1995 are projected to number roughly 200,000, up 60,000%....

Seismological Research Letters September 01, 1995, Vol.66, 3. doi:https://doi.org/10.1785/gssrl.66.5.3

INTRODUCTION

In recent years, the rapid expansion of the Global Seismographic Network (GSN) has greatly enhanced our ability to monitor seismic events. Equipped with very broadband, three-component sensors, the GSN stations provide good coverage on most continents and contribute high quality data to basic scientific research and other monitoring purposes. At the same time, several GSN stations in a region of particular interest may be considered as a sparse regional network and become invaluable assets for earthquake source studies because source parameters of small to moderate-sized earthquakes provide important constraints on the local crustal structure, the stress field and the regional tectonics. Previously, the source parameters of small earthquakes (M ∼ 4.2 to 4.5) were successfully obtained from regional waveform data recorded at a single, very broadband seismic station (Fan and Wallace, 1991). Several research groups have reported near-real time source parameters retrieved from broadband waveforms in the western United...

Seismological Research Letters September 01, 1995, Vol.66, 13-18. doi:https://doi.org/10.1785/gssrl.66.5.13

INTRODUCTION

The high levels of seismicity and thus seismic hazard in Central America are evident from the regular occurrence of large earthquakes. The steadily increasing levels of seismic risk in the same region are demonstrated by increasing damage and losses from these earthquakes, connected in general to increasing urbanization and infrastructure complexity. As such Central America constitutes one of the most important regions to focus on under the International Decade for Natural Disaster Reduction (IDNDR), and there is now a substantial number of projects and programs in the region under IDNDR auspices.

In this note we will describe some of the activities within and results from one of these projects, namely “Reduction of Natural Disaster in Central America, Earthquake Preparedness and Hazard Mitigation.” Building on a parallel Swedish effort, this project was set up in 1991 between Norway and the Central American countries of Guatemala, El Salvador, Honduras, Nicaragua, Costa...

Seismological Research Letters September 01, 1995, Vol.66, 19-25. doi:https://doi.org/10.1785/gssrl.66.5.19

INTRODUCTION

Since the original version of HYPOCENTER was published (Lienert et al., 1986), it has been used primarily to locate earthquakes using data collected by small networks of seismometers (e.g., Ambos et al., 1985). In its original form it suffered from many of the same limitations as its predecessors (HYPO71, HYPOINVERSE, etc.). It could not use azimuth data, was unable to force the calculation of specific phases (Pn, Pg, etc.) and was limited to locating events at station distances of less than about 500 km, due to a “flat earth” velocity model and coordinate system.

The increasing use of portable three-component seismometers has made it possible to determine the azimuth of a given event in addition to the arrival times of both primary and secondary phases. In principle, this allows single-station locations to be obtained, provided that the location software can use azimuth data. Global location capability is useful in...

Seismological Research Letters September 01, 1995, Vol.66, 26-36. doi:https://doi.org/10.1785/gssrl.66.5.26

The Reelfoot scarp in northwestern Tennessee is the surface expression of an east-verging fault propagation fold that overlies a southwest-dipping reverse fault. This fault is responsible for much of the current New Madrid seismicity and was probably the origin of the February 7, 1812, M 8.0 earthquake. Tectonic scarps in the Kentucky bend of the Mississippi River and at New Madrid, Missouri, appear to be a northwestern continuation of the Reelfoot scarp. Cores collected across the scarp in Kentucky where the topographic relief is 2.2 m reveal that the structural relief on a distinct subsurface fluvial sand bed is 4 m. One kilometer to the north the topographic relief is 3 m and structural relief is 4 m. Similarly, the scarp at New Madrid, Missouri, has 2 m of topographic and structural relief. These core data are compatible with trench observations to the south where the fold structure is reflected...

Seismological Research Letters September 01, 1995, Vol.66, 57-62. doi:https://doi.org/10.1785/gssrl.66.5.57

This report includes hypocenters for seismic events that occurred in November and December 1994 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 or more, (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.” Those made to agree with 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...

Seismological Research Letters September 01, 1995, Vol.66, 70-73. doi:https://doi.org/10.1785/gssrl.66.5.70

Letters

In the paper on the geotechnical aspects of the 1994 Northridge Earthquake in the May/June issue of SRL, depth to ground water of >15 m was reported for a ground failure zone in Granada Hills. This information was obtained from the Technical Appendix of the Los Angeles County Safety Element (dated 1990) and is mainly controlled by borings that are located to the south of the failure zone. Recent subsurface exploration performed by the U.S. Geological Survey (Daniel Ponti, Thomas Holzer, Suzanne Hecker, and their co-workers), suggests that ground water may be notably shallower (approx. 7 to 9 m) within the deformation zone. Very loose cohesionless sediments appear to be saturated, but the extent of these materials and the shallow ground water are still being investigated. This information is significant with respect to our interpretation of the likely ground failure mechanisms in this area. Interested readers are referred to U.S....

Seismological Research Letters September 01, 1995, Vol.66, 4. doi:https://doi.org/10.1785/gssrl.66.5.4

News & Notes

CUREe SYMPOSIUM IN HONOR OF GEORGE HOUSNER

In the first of a series of symposia to showcase the lifelong accomplishments of individuals contributing to the understanding of earthquakes, California Universities for Research in Earthquake Engineering (CUREe) will honor the career of Professor George Housner. For half a century, Professor Housner has been one of the country's leaders in the field of earthquake engineering.

The symposium will be held during the weekend of October 27–28, in Pasadena, California, at the Doubletree Hotel. Co-sponsored by the California Institute of Technology, the symposium will bring together scientists and engineers from around the country and overseas who will discuss the progress made in various areas pioneered by Professor Housner including structural engineering, ground motion, public policy and education. As well as making connections with Professor Housner's seminal work in these areas, the symposium presentations will include thoughts on future developments. Friday evening will feature...

Seismological Research Letters September 01, 1995, Vol.66, 5. doi:https://doi.org/10.1785/gssrl.66.5.5

Articles

INTRODUCTION

Regional seismograph networks can sometimes be used to locate impulsive atmospheric disturbances as well as earthquakes. Atmospheric events are difficult to detect in this manner because they usually transfer little seismic energy into the ground. Also, many modern digitally recording seismograph networks may fail to record atmospheric events if stations are spaced many tens of kilometers apart, and the networks utilize an event detection algorithm tuned to record earthquakes that generate seismic waves with apparent surface velocities greater than 5 km/sec. Nevertheless, the Pacific Northwest Seismograph Network (PNSN) sometimes records more slowly propagating sonic booms caused by supersonic aircraft, particularly when the aircraft pass over regions like Mount St. Helens having closely spaced seismographs. We describe two incidents in which seismic records have been used to track a space shuttle and a meteoroid traveling at supersonic speeds in the atmosphere.

REENTRY OF SPACE SHUTTLE INTO THE ATMOSPHERE

The reentry...

Seismological Research Letters September 01, 1995, Vol.66, 6-12. doi:https://doi.org/10.1785/gssrl.66.5.6

ANNUAL MEETING

Although I have met many Californians who are terrified of earthquakes, there have actually been relatively few fatalities in the past 75 years. We have relatively strict building codes in the United States and this has undoubtedly saved numerous lives. However, what is the vision for our future? Will we have manageable earthquakes or will we have some true catastrophes?

One extremely optimistic view is from a book by Robert Hill entitled “Southern California Geology and Los Angeles Earthquakes” published by the Southern California Academy of Sciences in 1928. The following quote is from the book cover. “This book completely refutes the prediction of Professor Bailey Willis that Los Angeles is about to be destroyed by earthquakes. It proves that this area is not only free from the probability of severe seismic disturbances, but has the least to fear from Acts of God of any city under the American flag.”

Seismological Research Letters September 01, 1995, Vol.66, 37-40. doi:https://doi.org/10.1785/gssrl.66.5.37

SEISMOLOGICAL SOCIETY OF AMERICA

91st ANNUAL MEETING

April 1–April 3, 1995 (Monday–Wednesday)

America's Center, St. Louis, Missouri, USA

To Obtain Latest Information

Email: ssa96@eas.slu.edu, Subject: HELP WWW URL: http://www.eas.slu.edu/Meetings/SSA96.html

Important Dates

Abstract Submission Deadline: January 8, 1996

Abstract Withdrawal Deadline: January 31, 1996

Program Available on URL: February 15, 1996

Hotel Reservation Cutoff: February 29, 1996

Preregistration Deadline: March 15, 1996

SSA 1996 Meeting: April 1–3, 1996

POINT OF CONTACT

Robert B. Herrmann

Professor of Geophysics

Department of Earth and Atmospheric Sciences

Saint Louis University

3507 Laclede Avenue

St. Louis, MO 63103 USA

TEL: 314 977 3120

FAX: 314 977 3117

Email: rbh@eas.slu.edu

CALL FOR PAPERS

Abstract Deadline

Friday January 8, 1996

Send abstracts to:

1996 SSA Program Committee

c/o Seismological Society of America

201 Plaza Professional Building

El Cerrito, CA 94530

Special forms for submitting abstracts are no longer supplied. Carefully follow the Instructions for Submitting Annual Meeting Abstract.

Seismological Research Letters September 01, 1995, Vol.66, 54-56. doi:https://doi.org/10.1785/gssrl.66.5.54

EQUIPMENT NEWS

INTRODUCTION

By mid-1991, many scientific successes had been achieved by applying observatory very broad-band (VBB) instrumentation to regional problems (e.g. Terrascope). This led to a perception within the community of a need for a portable high-dynamic range instrument that could be used for regional and global studies. Fortunately, the technology for such an instrument was just becoming available in the form of a low-power, integrated-circuit A/D of the delta-sigma modulation type and associated DSP (digital signal processor) from Crystal Semiconductor. Tests were performed which showed that the Crystal chip set could be incorporated into a PASSCAL instrument with suitable performance (Passmore and Patraw, 1992, 1993). Having demonstrated this performance, the Models 72A-07 High Resolution Digitizer and 72A-08 High Resolution Seismograph were designed and produced utilizing second-generation parts from Crystal Semiconductor. These parts consisted of a CS5323 Modulator and CS5322 Digital Filter, and they were incorporated onto a three-channel circuit card...

Seismological Research Letters September 01, 1995, Vol.66, 41-45. doi:https://doi.org/10.1785/gssrl.66.5.41

NEWS OF CORPORATE MEMBERS

EDITOR'S NOTE

The purpose of this column, “News of Corporate Members,” is to give the corporate members of the SSA a chance to interact with the SSA membership. This column is a forum where the corporate members can tell us about themselves and their work, changes in their organizations, and information or products they have produced that are of interest to seismologists or those who want to know more about seismology and its applications. It is my goal to have this column as a regular feature in SRL. This inauguration of “News of Corporate Members” contains a contribution from Digital Technology Associates, Inc., and is an introduction to their organization and work. I welcome all of our corporate members to submit news or other items for this column.

DIGITAL TECHNOLOGY, DISTRIBUTOR FOR GURLAP SYSTEMS

Digital Technology Associates, Inc. (DTA) is the U.S. distributor and Western Hemisphere representative for the broadband...

Seismological Research Letters September 01, 1995, Vol.66, 46. doi:https://doi.org/10.1785/gssrl.66.5.46

ELECTRONIC SEISMOLOGIST

THE INTERNET–UNDERGOING RAPID CHANGE

What is going to become of the Internet now that NSF is no longer subsidizing the backbone, and what are the implications for seismology of the resulting Internet upheaval? These are questions many of us worry about. We have become used to, if not dependent on, the Internet in many ways. From routine communications with colleagues and access to basic data, to obtaining meeting schedules, and other general information, many of us consider the Internet a fundamental necessity for our work. With the commercialization of the Internet, what does the future for this system look like, both in the short and long term? In this article I will take a stab at summarizing some of the bits of wisdom I hear from the network gurus regarding how the transition from NSF support is going and what the long-term prognosis is for the continued availability of this...

Seismological Research Letters September 01, 1995, Vol.66, 47-48. doi:https://doi.org/10.1785/gssrl.66.5.47

Book review

I am probably typical of most seismologists in that I don't usually pay attention to social science research on earthquakes. I have been to conferences where social scientists have given presentations on earthquakes, and I have read a couple of articles about the effects of earthquakes on society. However, recently a book entitled Promoting Risk: Constructing the Earthquake Threat came across my desk, and I decided to take a look at it. After reading a few pages I became absorbed by the topic, and soon I had read through the entire book. By the time I was finished, the editor in me said that I should get someone to review this for SRL. Various discussions between my right brain and left brain followed, and in the end I convinced myself that I should write the review of this book.

Promoting Risk was written by Robert A. Stallings, an associate professor...

Seismological Research Letters September 01, 1995, Vol.66, 49-50. doi:https://doi.org/10.1785/gssrl.66.5.49

NEW BOOKS & MEDIA

Abstract Journal in Earthquake Engineering

The 1994 volume of the Abstract Journal in Earthquake Engineering (Volume 24) is now available from the Earthquake Engineering Research Center. This journal provided convenient and comprehensive access to 1994 world literature in earthquake engineering and earthquake hazards mitigation. It includes 2400 abstracts from technical journals, research reports, books and other publications in 24 countries. It also includes the Proceedings of the Fifth U.S. National Conference on Earthquake Engineering. There is an extensive subject index, personal and corporate author index, an alphabetical list of titles and abstracts alphabetized by author within subsection. The topics covered include: General topics and Conference Proceedings; selected topics in seismology; engineering seismology; strong-motion seismometry; dynamics of soils, rocks and foundations; dynamics of structures; earthquake-resistant design and construction; earthquake damage; earthquakes as natural disasters. The price for U.S., Canada and Mexico addresses is US $100.00. All other addresses—US $125.00. For more...

Seismological Research Letters September 01, 1995, Vol.66, 51-53. doi:https://doi.org/10.1785/gssrl.66.5.51

EASTERN SECTION

ES-SSA 1995

FINAL ANNOUNCEMENT EASTERN SECTION SEISMOLOGICAL SOCIETY OF AMERICA 67TH ANNUAL MEETING

Date: Thursday, October 12 - Friday, October 13, 1995

Seismological Research Letters September 01, 1995, Vol.66, 63-69. doi:https://doi.org/10.1785/gssrl.66.5.63

MEETING CALENDAR

SEPTEMBER, 1995

September 13–15 Deformation-enhanced Melt Segregation and Metamorphic Fluid Transport, Edinburgh Scotland

Sponsored by Mineralogical Society, Geological Society of London. (M. Holness, Dept. Geology and Geophysics, University of Edinburgh, West Mains Road, Edinburgh E119 3JW Scotland. Phone 031-650-8544, fax 031-668-3184. e-mail marian.holness@gig.ed.ac.uk)

OCTOBER, 1995

October 1–5 American Institute of Professional Geologists 1995 Annual Meeting—Prosperity and Professional Geology, Denver, CO

(Conference Associates, 1776 Lincoln Street, Suite 620, Denver, CO 80203. Phone 303-863-9506; Fax 303-863-9507.)

October 12–13 Seismological Society of America, Eastern Section Annual Meeting, Palisades, NY.

(Lamont-Doherty Earth Observatory of Columbia University. Contact Noel Barstow; Phone 914-365-8477 (8486), e-mail Barstow@lamont.ldgo.columbia.edu) Abstract Deadline September 8, 1995.

October 17–1 Fifth International Conference on Seismic Zonation, Nice, France

Organized by EERI and French Association for Earthquake Engineering (AFPS). (EERI, 499 14th St., Suite 320, Oakland, CA USA 94612-1902. Phone 510-451-0905, fax 510-451-5411.)

NOVEMBER, 1995

November 6–9 Geological Society of America Annual Meeting, New...

Seismological Research Letters September 01, 1995, Vol.66, 74-76. doi:https://doi.org/10.1785/gssrl.66.5.74
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