HR: 0830h
AN: S41C-0100    [PDF]
TI: The Dynamics of Strike-Slip Faults with Stepovers and Linking Dip-Slip Faults
AU: * Oglesby, D D
EM: david.oglesby@ucr.edu
AF: Department of Earth Sciences, University of California, Riverside, CA 92521 United States
AB: One of the most important issues in seismology is the potential size of future earthquakes. Dynamic models of strike-slip faults with stepovers have shown that under certain circumstances, rupture can jump from segment to segment, increasing the size of potential earthquakes beyond that which would be expected from the size of the individual segments. Studies of offset thrust faults have shown that linking tear (strike-slip) faults can greatly increase the distance over which rupture can jump. Using the 3-D dynamic finite element method, we extend this line of research to study parallel strike-slip fault segments linked by either a thrust or normal fault, depending on the whether the stepover is compressional or dilational. We find that in all cases, a linking fault greatly increases the distance over which rupture can jump, and increases the size of the final event. However, slip on the strike-slip segments increases the compressive normal stress on a thrust fault in a compressive stepover, and decreases the compressive normal stress on a normal fault in a dilational stepover. This effect causes the dilational/normal faulting stepover to be more conducive to multi-segment events than the compressive/thrust stepover. This result is consistent with studies of systems with no linking faults. Additionally, the orientation (dip direction) of the linking dip-slip fault leads to the effect that jumping rupture is more likely for ruptures that approach the stepover from a certain direction. Interaction between the static and dynamic stress fields in the stepover region leads to further complications. The results may lead to more accurate forecasts of earthquake size and seismic hazard in places where linked stopovers occur, such as the San Francisco bay region.
DE: 3210 Modeling
DE: 7209 Earthquake dynamics and mechanics
DE: 7260 Theory and modeling
SC: Seismology [S]
MN: 2003 Fall Meeting