HR: 0800h
AN: S21C-0719    [Abstracts]
TI: Earthquake occurrence in regional-scale fault models with rate- and state-dependent friction
AU: * Richards-Dinger, K
EM: keithrd@ucr.edu
AF: Department of Earth Sciences, University of California, Riverside, Riverside, CA 92521- 0423, United States
AU: Richards-Dinger, J
EM: dieterichj@ucr.edu
AF: Department of Earth Sciences, University of California, Riverside, Riverside, CA 92521- 0423, United States
AB: Long-term (~10,000 year) catalogs of simulated earthquakes can be used to address a host of questions related to both seismic hazard calculations and more fundamental issues of earthquake occurrence and interaction (e.g. Ward [1996], Ziv and Rubin [2000, 2003], Rundle et al. [2004]). With a goal of simulating earthquake occurrence in geometrically complex, regional-scale fault networks (such as the SCEC Community Fault Model) at a resolution on the order of 1 km², we have extended the models of Dieterich [1995] and Ziv and Rubin [2000, 2003] for faults which obey rate- and state-dependent frictional laws to handle fault elements of arbitrary orientation and slip mode. These simulations are computationally very efficient as they use analytic expressions for the nucleation process that include the effects of time-varying normal stress. We will present work on our exploration of how both geometry (fractal roughness, offsets, bends, and other simple but non-planar) and material property heterogeneities affect aspects of earthquake occurrence such as a) frequency-magnitude distribution, b) spatial and temporal clustering, c) multi-segment ruptures, and d) recurrence statistics in our simulations. Interesting results so far include: the surprisingly small effect of random fractal roughness on the frequency-magnitude distribution for single-fault models driven by uniform backslip but a profound effect in such models driven by tapered backslip; contrasting preferential nucleation locations for small and large events; the occurrence of paired large events with time separations of seconds to years in models consisting of two parallel faults separated by an offset; and the transition of the recurrence time distribution for large events from nearly periodic (coefficient of variation of ~0.04) to much more random (coefficient of variation of ~0.9) with the addition of large-scale bends and additional sub-parallel fault strands in models loosely based on southern California.
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
DE: 7290 Computational seismology
SC: Seismology [S]
MN: 2007 Fall Meeting