HR: 0830h
AN: G41A-0199
TI: Integrated Kinematic Analysis of GPS and Fault Slip Data in the Eastern California Shear Zone, Walker Lane and Sierra Nevada
AU: * Hammond, W C
EM: bhammond@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Rd. MS977, Menlo Park, CA 94025 United States
AU: Thatcher, W
EM: bhammond@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Rd. MS977, Menlo Park, CA 94025 United States
AB: The Sierra Nevada (SN) microplate moves roughly N50?W with respect to North America (NA), around an Euler pole that lies in the Pacific (PA) basin to the west and south. Its motion is indicative of processes governing the deformation of the Walker Lane and Eastern California Shear Zone, accommodating east to west expansion of the Basin and Range and approximately 25\% of PA/NA dextral shear. To date, estimates for the location of the SN/NA pole obtained by GPS, VLBI and geologic data differ by at least 30 degrees [e.g. Argus and Gordon, 1996; Hearn and Humphreys, 1998]. The difference between these poles may, in part, be attributable to the type of data used in the analyses. The GPS determined velocity field potentially contains artifacts of the earthquake cycle such as recoverable elastic deformation preceded by slip at depth, fault creep, and viscoelastic relaxation following earthquakes on block bounding faults. We use Global Positioning System (GPS), fault strike and slip rate data to constrain the kinematics of the eastern boundary of the Sierra Nevada (SN) microplate, and western Basin and Range province of western North America. Data include previously published GPS measurements [Bennet et al., 1998; Thatcher et al., 1999; Gan et al., 2000; Svarc et al., submitted manuscript 2001], recently collected GPS data, and recently compiled fault maps of Nevada and California that include fault strike, slip sense and slip rate estimates. GPS velocities are refined with the Quasi Observation Combination Analysis algorithm of Dong et al. From these data we constrain the spatial variation in the rate and style of deformation throughout the region, and identify components of the deformation that are relevant to interaction of the PA/NA transform margin and Basin and Range extension. Using two-dimensional viscoelastic finite elements we derive kinematic models representative of the instantaneous (GPS) time scale, in preparation for future modeling of the longer term (Quaternary and Holocene) time scale. We determine the continuous elastic deformation field that is most consistent with the GPS data, kinematic consistency within the modeled domain, and boundary conditions imposed by PA/NA motion.
DE: 1206 Crustal movements--interplate (8155)
DE: 1236 Rheology of the lithosphere and mantle (8160)
DE: 8110 Continental tectonics--general (0905)
DE: 8123 Dynamics, seismotectonics
DE: 8164 Stresses--crust and lithosphere
SC: G
MN: 2001 AGU Fall Meeting