HR: 0800h
AN: S21B-0573    [Abstracts]
TI: Simulations of Stress Drops for Evolving Seismicity on a Heterogeneous Fault in an Elastic Half-space
AU: * Bailey, I W
EM: iwbailey@usc.edu
AF: University of Southern California, Department of Earth Sciences, Los Angeles, CA 90007, United States
AU: Ben-Zion, Y
EM: benzion@usc.edu
AF: University of Southern California, Department of Earth Sciences, Los Angeles, CA 90007, United States
AB: Understanding what limits the size of earthquake stress drops has important implications for estimating ground motion. Seismological derivations of stress drops are typically of order ~1-10 MPa, yet theoretical estimates based on laboratory friction data and measurements of stress in the crust are two orders of magnitude higher. The discrepancy may stem from the fact that earthquake stress drops are average values over a rupture area that may have highly heterogeneous initial stress, while the theoretical estimates assume an essentially homogeneous stress. We investigate properties of stress drops in simulations of evolving seismicity and stress field on a strongly heterogeneous fault. The model fault (Ben-Zion and Rice, 1993) consists of a set of inherently- discrete slip patches surrounded by a 3-D elastic half-space. The discrete slip patches provide a simple representation of heterogeneities associated with segmentation and other geometrical complexities. Previous studies have shown that the model produces many statistical features of seismicity compatible with observations including frequency-size and temporal event statistics, hypocenter distributions, intermittent criticality, and scaling of source-time functions. We apply similar analyses to understand how stress drops in an evolving heterogeneous stress field depend on rheological properties of the model (spatial distribution of static/kinetic friction values and coefficients of power law creep), hypocentral depth, earthquake magnitude and temporal position within large earthquake cycles.
DE: 4430 Complex systems
DE: 7209 Earthquake dynamics (1242)
DE: 7212 Earthquake ground motions and engineering seismology
DE: 7215 Earthquake source observations (1240)
DE: 8118 Dynamics and mechanics of faulting (8004)
SC: Seismology [S]
MN: 2007 Fall Meeting