HR: 1340h
AN: S53A-1077    [Abstracts]
TI: Dynamics Of Parallel Strike-Slip Faults Over Multiple Earthquake Cycles: Heterogeneous Stress Near The Step-Over
AU: * Duan, B
EM: benchun.duan@email.ucr.edu
AF: Department of Earth Sciences, University of California, Riverside, CA 92521
AU: Oglesby, D D
EM: david.oglesby@ucr.edu
AF: Department of Earth Sciences, University of California, Riverside, CA 92521
AB: We combine a 2D elastodynamic model for the coseismic process and a 2D viscoelastic model for the interseismic process to study the dynamics of two parallel offset strike slip faults over multiple earthquake cycles. The elastodynamic model is simulated numerically by a new explicit finite element code. The viscoelastic model (using an analytical solution) approximates stress loading and relaxation on faults during the interseismic period. We examine different combinations of width and overlap or gap of the step-over. We find that fault stresses become highly heterogeneous after multiple cycles near the step-over region. This heterogeneity in fault stresses can have significant effects on rupture initiation, event patterns, and the ability of rupture to jump the segment offset. Low stress regions near the step-over are favorable locations for rupture initiation. After a number of events, the fault system tends to develop a steady state in which the fault stress and event pattern are stable. In the steady state we typically see one of two patterns: 1) rupture alternates between the two faults in two consecutive events, and 2) the two faults rupture together in all events. The heterogeneous stress pattern that develops over multiple earthquake cycles results in rupture being able to jump wider fault offsets than has been observed in numerical studies with homogeneous initial stresses. These results are consistent with field data and may have important implications for seismic hazard analysis.
DE: 7209 Earthquake dynamics (1242)
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
DE: 7290 Computational seismology
SC: Seismology [S]
MN: Fall Meeting 2005