HR: 16:45h
AN: S14B-04    [Abstracts]
TI: Normal Stress and Gaps in Interacting Strike-Slip Faults
AU: * Oglesby, D D
EM: david.oglesby@ucr.edu
AF: Department of Earth Sciences, University of California, Riverside, Riverside, CA 92521, United States
AB: One of the pressing issues in seismic hazard analysis is the probability of earthquake rupture jumping between fault segments, resulting in a large cascading event. Researchers (e.g., Wesnousky, 2006) have conducted observational surveys to determine the maximum width of stepover that rupture may jump in strike-slip systems, and other researchers (e.g., Harris et al., 1991; Kase and Kuge, 1998; Harris and Day, 1999) have used numerical methods to study the dynamics of such systems. Both methods imply that ruptures have difficulty propagating across stepovers with widths greater than 3-4 km, with possible differences between compressional and extensional stepovers. The present study extends the numerical modeling work above to address some remaining questions, such as 1) What is the role of the time-dependent normal stress in extensional and compressional stepovers, and 2) How does the presence of an along-strike fault overlap or gap affect the ability of rupture to propagate through stepovers? I find that decreases in the time-dependent normal stress field radiated by the primary fault facilitate jumping rupture in both extensional and compressional stepovers. Removing normal stress dependence from the friction law reduces the maximum jump distance in both extensional and compressional cases. In addition, an along-strike gap makes it much more difficult for rupture to propagate through an extensional stepover than a compressional stepover. The results may have implications for seismic hazard in near multi-segment strike-slip systems.
DE: 7209 Earthquake dynamics (1242)
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
DE: 7290 Computational seismology
SC: Seismology [S]
MN: 2007 Fall Meeting