HR: 09:30h
AN: G21A-05 INVITED     [Abstracts]
TI: Historical Deformation Models of the San Andreas Fault System: Integrating 1000 Years of Earthquake Activity With Modern Deformation Measurements
AU: * Smith, B R
EM: brsmith@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr. MC 0225, La Jolla, CA 92093-0225 United States
AU: Sandwell, D T
EM: dsandwell@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr. MC 0225, La Jolla, CA 92093-0225 United States
AB: Geologic, geodetic, and seismic data are integrated into a semi-analytic earthquake cycle model to simulate deformation and stress along the entire San Andreas Fault System over the past 1000 years. The 3-D time-dependent model consists of multiple interacting fault strands embedded in an elastic layer overlying a viscoelastic half-space. The model efficiently simulates interseismic stress accumulation on the upper locked portion of faults, major earthquakes on prescribed fault segments, and the viscoelastic response of the underlying half-space following major ruptures. We simulate 1000 years of the earthquake cycle along the San Andreas Fault System using estimates of both long-term (geologically determined) interseismic slip and coseismic slip estimated from paleoseismic and historical earthquake data. The model is further refined by present-day horizontal and vertical geodetic observations in order to provide bounds on elastic plate thickness (> 60 km) and half-space viscosity (> 2x10 ¹⁸ Pa s). Using these model parameters, we calculate a model time-series for both 3-D deformation and Coulomb stress spanning the past 200 years. Coulomb stress models show large amounts of accumulated stress prior to major events (ie., 1857, 1906), while the present-day model snapshot identifies significant regions of stress along the majority of the southern San Andreas, as expected from the absence of major earthquakes in the region for over the past 150-300 years. Finally, a time-series of the vertical deformation component of the model is compared with relative sea level changes recorded by coastal tide gauges since 1917. Using these data, we explore both our best geodetically-determined model and a suite of alternative models in order to place further constraints on acceptable model parameters.
UR: http://topex.ucsd.edu/body_force
DE: 1206 Crustal movements--interplate (8155)
DE: 1242 Seismic deformations (7205)
DE: 3210 Modeling
DE: 8164 Stresses--crust and lithosphere
DE: 8199 General or miscellaneous
SC: Geodesy [G]
MN: 2005 Joint Assembly