HR: 09:45h
AN: S51F-07    [Abstracts]
TI: An Oblique/Branched Fault System: Dynamic and Static Analyses
AU: * Colella, H
EM: hcolella@gmail.com
AF: California State University - Fullerton, Department of Geological Sciences 800 N. State College Blvd., Fullerton, CA 92834-6850 United States
AU: Oglesby, D
EM: dolgesby@ucr.edu
AF: University of California - Riverside, Department of Earth Sciences, Riverside, CA 92521-0423 United States
AU: Bowman, D D
EM: dbowman@fullerton.edu
AF: California State University - Fullerton, Department of Geological Sciences 800 N. State College Blvd., Fullerton, CA 92834-6850 United States
AB: We use a dynamic 3-D finite element analysis to investigate slip partitioning and rupture propagation on a branched fault system. The fault geometry is that of an oblique fault at depth that branches into vertical and dipping segments near the surface. We find that oblique slip on the basal fault results in partitioned slip on the near-surface faults, with more strike-slip motion at the surface trace of the vertical fault, and more dip-slip motion at the surface trace of the dipping fault. This result is in qualitative agreement with static models of similar systems. When the slip on the basal fault includes a normal component, the preferred rupture propagation is upward to the vertical surface fault. Conversely, a thrust component of slip on the base fault results in preferred propagation upward to the dipping surface fault. These results indicate that the stress interactions within geometrically complex fault systems can lead to complexity in rupture propagation, including a crucial dependence on the direction of slip. The results of this modeling are compared to slip partitioning observed in the 2001 M=7.8 Kokoxilli, China earthquake.
DE: 7209 Earthquake dynamics (1242)
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
DE: 7260 Theory
DE: 7290 Computational seismology
SC: Seismology [S]
MN: Fall Meeting 2005