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Three AGU Special Session Announcements

Date: 08/28/2008

We'd like to draw your attention to three special sessions at this year's AGU Fall Meeting in San Francisco, December 15-19:

Session G02: "Plate Motion and Its Relation to Deforming Zones"

We seek geodetic and geologic studies on plate motion, microplate motion, and their relation to elements in the deforming zones between the plates-faults, slip, great earthquakes, and mountains and rifts generated by active deformation. Important questions relevant to this session include: What fraction of plate motion is being taken up by elastic strain that will be released in earthquakes? What fraction is being taken up by permanent strain that is becoming part of the geologic record? Are deforming belts better described by microplates or by a homogeneous medium? Do estimates of plate motion from magnetic anomalies, transform azimuths, and earthquake slip vectors differ significantly from those from geodetic techniques, such as GPS, VLBI, SLR, and DORIS? We are interested in presentations using all types of data to constrain plate motions and deforming zones, not only geodetic data.

Sponsor: Geodesy
Conveners: Donald F. Argus (Donald.F.Argus@jpl.nasa.gov) and Jeffrey T. Freymueller (jeff.freymueller@gi.alaska.edu)

Session T06: "Seismic Fault Zone Rocks"

Exhumed faults provide important opportunities for extracting information on earthquake and fault mechanics (e.g., rupture geometries, operating stress field, earthquake energy budgets, etc.) by means of field studies, complementary to drilling projects of active faults, rock deformation experiments and seismology. Not all exhumed faults were necessarily seismic during their activity, and at present only tectonic pseudotachylytes (solidified friction-induced melts produced during seismic slip) are unambiguously recognized as the signature of ancient earthquakes in exhumed faults. However, the occurrence of pseudotachylytes is not as widespread as seismic activity in the Earth crust is. It follows that the interpretation of most fault zone assemblages (cataclasites, fault gouges, pulverized rocks, etc.) remains enigmatic. Which fault zone rocks other than pseudotachylytes have been produced during earthquakes? We welcome field, theoretical and experimental contributions focused on two broad problems: (i) discriminating fault zone rocks produced during earthquakes. What are the microstructural, chemical, physical, and mineralogical features that can help discriminate rocks produced during seismic vs. aseismic slip? (ii) The problem of learning about earthquake mechanics from seismic fault zone rocks. For example, how do rocks record the stress and heat pulses typical of earthquakes?

Conveners: Giulio Di Toro, Yehuda Ben-Zion, Karen Mair, Chris Marone
Invited speakers: Stefan Nielsen, Tom Rockwell, Steve Hickman, Takehiro Hirose

Session S16: "Crust and Upper Mantle Structural Models beneath the Central and Eastern US"

The 1811-1812 New Madrid series of earthquakes occurred in a relatively unpopulated region of the central United States between Memphis and St. Louis and were felt over most of the central and eastern United States and some parts of Canada, a felt area nearly 20 times larger than the area impacted by the similarly sized 1906 San Francisco earthquake. A better understanding of the temporal and spatial distribution of shaking and damage from St. Louis to Memphis that accompanied the great 1811-1812 earthquakes and other historic events, will reduce uncertainty about potential damage from similar earthquakes as well as provide the public with a provocative view of the potential impact of a recurrence of these events. In order to perform realistic computer simulations of such earthquakes and assess seismic hazard, updated comprehensive and detailed structural models are needed for the region. This session seeks contributions that constrain the lithologic, tectonic, geophysical and geotechnical structure of the Central United States lithosphere. Contributions that address solutions to complications arising from attempts to image within and beneath thick sedimentary basins are particularly encouraged.

For more information, please contact one of the conveners:

Heather Deshon (hdeshon@memphis.edu), Oliver Boyd (olboyd@usgs.gov), Jer-Ming Chiu (chiu@ceri.memphis.edu), and Leonardo Ramirez-Guzman (lramirez@andrew.cmu.edu)