HR: 1340h
AN: S53A-0179    [Abstracts]
TI: The Relationships Between Earthquakes, Faults, and Recent Glacial Fluctuations in Southern Alaska
AU: * Wiest, K R
EM: wiest@geo.utep.edu
AF: Department of Geological Sciences, University of Texas at El Paso, El Paso, TX 79968 United States
AU: Sauber, J M
EM: jeanne@steller.gsfc.nasa.gov
AF: Laboratory for Terrestrial Physics, NASA's Goddard Space Flight Center, Greenbelt, MD 20771 United States
AU: Doser, D I
EM: doser@geo.utep.edu
AF: Department of Geological Sciences, University of Texas at El Paso, El Paso, TX 79968 United States
AU: Hurtado, J M
EM: hurtado@geo.utep.edu
AF: Department of Geological Sciences, University of Texas at El Paso, El Paso, TX 79968 United States
AU: Velasco, A A
EM: velasco@geo.utep.edu
AF: Department of Geological Sciences, University of Texas at El Paso, El Paso, TX 79968 United States
AB: In southern Alaska, northwestward-directed subduction of the Pacific plate is accompanied by accretion of the Yakutat terrane to continental Alaska. In the tectonically complex region between the transcurrent Fairweather fault and the Alaska-Aleutian subduction zone, active crustal shortening and strike-slip faulting occurs. Since a series of large earthquakes in 1899 (Mw = 8.1, Yakataga; Mw=8.1 Yakutat), there has been only one large event (1979 St. Elias Mw = 7.4) in the Yakutat region between the aftershock zones of the 1964 Prince William Sound (Mw = 9.2) and 1958 Fairweather (Mw = 8.2) earthquakes. In this region, the glaciers are extensive and many of them have undergone significant retreat in the last 100 years. This study investigates the relationships between small to moderate magnitude events, ongoing crustal deformation, active geological structures in the region, and recent glacial fluctuations. To map earthquake locations with respect to current glacier positions, we will incorporate Ice Cloud and land Elevation Satellite (ICESat) data into an updated Digital Elevation Model (DEM) of key glaciated regions that has been created using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images in conjunction with Shuttle Radar Topography Mission (SRTM) data. For the seismological investigation, we focused on relocating events that have occurred since the last large earthquake at St. Elias in 1979 using data obtained from the Alaska Earthquake Information Center (AEIC). P-wave polarity first motion focal mechanisms were generated for the relocated events and evaluated. Our preliminary relocations suggest a dipping slab in cross-section and also show a number of shallow event clusters around local glaciers. The focal mechanisms are quite variable but, in general, indicate strike-slip and oblique-slip focal mechanisms. Some of our highest quality focal mechanisms show dip-slip faulting and are from shallow events located near glacial boundaries. For mapping the correlation of earthquakes to geological structures, we will use 3D visualization software to plot relocated events and correlate them with shallow structures in the region.
DE: 7223 Seismic hazard assessment and prediction
DE: 7230 Seismicity and seismotectonics
DE: 8102 Continental contractional orogenic belts
DE: 1827 Glaciology (1863)
DE: 1243 Space geodetic surveys
SC: Seismology [S]
MN: 2004 AGU Fall Meeting