SSA 2002 Annual Meeting

Technical sessions:
17-19 April 2002 (Wednesday-Friday)

Some Special Session Topics:

Nisqually and Other Warm Slab Earthquakes
Convenors: K. Creager, R. Crosson (Department of Earth and Space Sciences, University of Washington, Geophysics AK-50, Seattle, WA 98195,,, and S. Kirby (USGS, Menlo Park, CA 94025,

This session will focus on seismological, geodetic, geological and geotechnical studies of the 28 February 2001 Nisqually earthquake and comparisons with the 24 March 2001 Geiyo earthquake in Japan, as well as other intraslab earthquakes in warm-slab environments. What is the relation of these large earthquakes to microearthquake patterns, 3D elastic structure, fluids, chemistry, and metamorphic petrology of this dynamic system? How do these studies help define the hazard associated with intraslab earthquakes?

Seismicity and Seismic Hazards of Stable Continents
Convenors: John Adams (National Earthquake Hazards Program, Geological Survey of Canada, 7 Observatory Cres., Ottawa, ON, K1A 0Y3 Canada, and Clark Fenton (Seismic Hazards Group, URS Corporation, 500 12th Street, Suite 200, Oakland, CA 94607-4014,

The low rate of earthquake activity of many "stable" continental areas makes assessing their seismic hazard difficult. Uncertainties in the seismotectonic character of any one area are large, as are uncertainties in how various continental areas compare to each other. Why was Australia so active in the 20th century and North America not? Are these differences temporal fluctuations or representative of long-term behavior? Many fields of study are relevant to answering these questions: paleoseismicity, historical and instrumental seismicity, considerations of the size of the largest earthquake (Bhuj-sized?), and the nature of the continental earthquake source. Furthermore, different assessments of the parameters can lead to very different assessments of the hazard, particularly for critical structures designed against low-probability hazard events. This session will provide a forum for recent advances in our understanding of continental tectonics and seismic hazard.

Urban Seismology and Site Response Studies
Convenors: John Cassidy (Canadian National Earthquake Hazards Program, Geological Survey of Canada, P.O. Box 6000, Sidney, BC, V8L 4B2 Canada,, Ned Field, and David Wald (USGS, 525 South Wilson Ave., Pasadena, CA 91106-3212,,

Urban seismograph networks deployed around the world are providing new insight into earthquake hazards. This session will focus on urban seismic networks and deployments of portable instruments in urban areas and their application to detailed site-response studies, soil nonlinearity, basin response, and the contribution of both shallow and deeper structure to the variation in earthquake ground shaking across urban areas. Papers on the use of urban networks for disaster preparedness and response are also encouraged.

Deformation, Transients, and Neotectonics
Convenor: Herb Dragert (Geological Survey of Canada, P.O. Box 6000, Sidney, BC, V8L 4B2 Canada,

Modern space-based geodetic techniques and state-of-the-art ground-based strain monitoring techniques are providing increasingly accurate observations of crustal motions over a wide range of spatial and temporal scales which are relevant to present-day tectonics and the study of earthquakes. This session invites contributions that discuss new insights into crustal mechanics derived from the observation and the modeling of surface deformation and strain. Of particular interest are short-lived (hours, to days, to months) transient processes which may play a significant role in the cycles of stress accumulation and stress redistribution both before and after large earthquakes.

Recent Advances in Event Location and Source Discrimination
Convenors: David McCormack (Geological Survey of Canada, 7 Observatory Cr., Ottawa, ON, K1A OY3 Canada, and Kin-Yip Chun (Department of Physics, University of Toronto, Toronto, ON, M5S 1A7 Canada,

This session will cover research advances in event location, calibration, and source discrimination of relevance to explosion monitoring and arms-control treaty verification. Presentations which relate to the development and use of the International Monitoring System or which deal with integration of seismic and acoustic data are particularly encouraged.

Cascadia Seismicity, Paleoseismology, and Seismic Hazard
Convenors: Garry Rogers (National Earthquake Hazards Program, Geological Survey of Canada, P.O. Box 6000, Sidney, BC, V8L 4B2 Canada, and Brian Atwater (USGS, University of Washington, Box 351310, Seattle, WA 98195,

Recent findings on crustal and plate boundary earthquakes in the Cascadia region.

Cascadia Marine Seismic Structure and Offshore Seismicity
Convenors: George Spence (School of Earth and Ocean Sciences, University of Victoria, Victoria, BC, V8W 3P6 Canada, and Michael Riedel (Geological Survey of Canada, P.O. Box 6000, Sidney, BC, V8L 4B2 Canada,

This session highlights recent analyses of marine seismic studies in Cascadia and offshore seismicity and tectonics west of the Cascadia Subduction Zone.

Seismological Studies of the Continental Lithosphere
Convenors: M. Bostock (Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC, V6T 1Z4 Canada, and G. Humphreys (Department of Geological Sciences, University of Oregon, Eugene, OR 97403-1272,

The continents comprise assemblages of crustal and mantle rocks that have experienced a complex history of magmatism and metamorphism. At active convergent margins, subduction processes drive the formation of thin, young lithosphere. In the ancient cratons, the mantle lithosphere appears to be exceptionally thick (> 200 km) and to have been preserved over long periods of time. New insights into the dynamic processes which create, preserve, and modify continental lithosphere are being obtained from seismological studies of subcontinental structure, especially from data sets collected by high-density, temporary deployments of broadband seismometers. The purpose of this session is to compare the results from seismological studies of the continental mantle and discuss their implications for dynamical and evolutionary models. The aspects of continental structure to be considered include high-resolution tomography, seismic anisotropy, the structure of upper-mantle discontinuities, scattering by small-scale heterogeneities, and petrological controls on density and seismic velocities.

New Perspectives on the Use of Historical Seismograms
Convenors: Phil Cummins (IFREE/JAMSTEC, 2-15 Natsushima-cho, Yokosuka 237-0061, Japan, and Diane Doser (University of Texas, El Paso, Texas,

Studies in the past decade which have applied modern analytical techniques to the analysis of historical seismograms show that such records continue to supply a wealth of information about earthquake cycles and source processes. At the same time, archiving facilities are under increasing pressure to dispose of these records in order to conserve space. For this session we invite contributions demonstrating the value of these records, particularly through the application of modern analytical methods to extract new information about historical earthquakes. We also hope to provide a venue for the exchange of information about the utilization of new technology for archiving and digitizing historical records.

Seismic Processes of Active Volcanoes: Observations and Modeling
Convenors: Rick Aster (New Mexico Institute of Mining and Technology, Socorro, NM, and Susan Schwartz (University of California, Santa Cruz, CA,

Interactions between brittle, elastic, and fluid-gas dynamic processes in active volcanoes produce a great variety of seismic signals, most of which are as yet poorly understood. Study of active volcanoes in recent years with broadband seismometry—increasingly coupled with acoustic, ground deformation, video, and other multidisciplinary observations—has resulted in many new data sets which illuminate long-recognized event types such as long-period earthquakes and short-period tremors at higher fidelity and with better geographic coverage. Broadband and associated observations have also frequently revealed new event types, such as very long-period (> 10 s) pulses/resonances and degasing transients and continuous signals. This session invites seismological, observational, theory, and modeling contributions from active volcanoes worldwide.

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Last Update: 22 January 2002