HR: 1340h
AN: G13A-0913    [Abstracts]
TI: Study of the postseismic deformation transient due to the Mw6 2004 Parkfield earthquake using a new 3-D semi-analytic model of stress-driven fault creep.
AU: * Barbot, S
EM: sbarbot@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr 0225, La Jolla, CA 92093, United States
AU: Fialko, Y
EM: yfialko@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr 0225, La Jolla, CA 92093, United States
AB: We developed a new semi-analytic model of time-dependent aseismic fault slip driven by coseismic stress changes. The model uses elastic Greens functions, expressed analytically in the Fourier domain, to solve for the displacement due to an arbitrary set of body forces in a 3-D computational grid representing a heterogeneous visco-elastic half-space. The numerical approach makes use of the convolution theorem and the fast Fourier transform, with number of operations scaling as N Log N (N being the grid size). Strike-slip as well as dip-slip faults of arbitrary orientation can be modeled using an equivalent body-force representation. Realistic fault geometries are easily included by taking advantage of the superposition theorem. Benchmark simulations show that our model compares favorably to known analytic solutions. We apply the model to investigate the postseismic transient following the Mw6 2004 Parkfield (California) earthquake. We use the slip model for the Parkfield event to calculate the coseismic stress changes that in turn are relaxed on the rest of the fault via aseismic creep. We use several rheologic relationships to study the evolution of postseismic afterslip. The model predictions are compared to data from continuous GPS stations in the near field of the rupture. We identify a range of dynamic (stress- driven) models that render a good agreement with both coseismic and postseismic deformation measurements.
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 1242 Seismic cycle related deformations (6924, 7209, 7223, 7230)
DE: 6924 Interferometry (1207, 1209, 1242)
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
SC: Geodesy [G]
MN: 2007 Fall Meeting