HR: 1340h
AN: S53A-1079    [Abstracts]
TI: On Nucleation Properties and Spatio-Temporal Slip Evolution of Simulated Seismicity
AU: * Hillers, G
EM: hillers@sed.ethz.ch
AF: ETH Zurich, Institute of Geophysics ETH Hoenggerberg HPP, Zurich, 8093 Switzerland
AU: Mai, M
EM: mai@sed.ethz.ch
AF: ETH Zurich, Institute of Geophysics ETH Hoenggerberg HPP, Zurich, 8093 Switzerland
AU: Ben-Zion, Y
EM: benzion@usc.edu
AF: University of Southern California, Department of Earth Sciences University of Southern CA, Los Angeles, CA 90089-0740 United States
AB: Previous studies of spatio-temporal evolution of slip on a fault governed by rate-and-state friction employed frictional properties corresponding to fairly homogeneous faults. In most cases, the only types of heterogeneities were the lab-based depth-variations of the parameters a and b that produce transitions between stable velocity-strengthening and unstable velocity-weakening regimes. In this study we use a constant a-b profile in the seismogenic zone and heterogeneous distributions of the critical slip distance L along strike and depth to model geometrical heterogeneities of fault structures. More specifically, we perform 3D quasi-static and quasi-dynamic simulations of slip on a strike-slip fault in a continuum framework. We use families of 2D anisotropic correlated distributions of L having different correlation lengths along strike (ax) and downdip (az). We explore systematically the significance of the geometrical parameters ax, az, and the underlying distribution of L values across the fault (Gaussian or uniform) on nucleation properties and frequency-size statistics. The variations of L are chosen to provide approximate representations of faults at different evolutionary stages. Relatively smooth mature faults (like the San Andreas) are represented with distributions that have large correlation length, while distributions with small correlation lengths are used to represent rougher immature faults (like the San Jacinto and faults in the eastern CA shear zone). The 3D code with various cases of anisotropic correlated distributions of L is used to study additional issues related to observed complex behavior of seismogenic faults. These include: (1) Nucleation and arrest properties of failure episodes on heterogeneous faults governed by RSD friction. (2) Correlation between the size of the nucleation zone and the final size of simulated slip events. (3) Comparison between properties of final simulated slip histories and those of the inverted slip histories. (4) Properties of evolving stress on a heterogeneous fault governed by rate-and-state friction.
DE: 4430 Complex systems
DE: 7209 Earthquake dynamics (1242)
DE: 8118 Dynamics and mechanics of faulting (8004)
DE: 8123 Dynamics: seismotectonics
SC: Seismology [S]
MN: Fall Meeting 2005