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Evidence from coseismic slip gradients for dynamic control on rupture propagation and arrest through stepovers

Austin J. Elliott, James F. Dolan, & David D. Oglesby

Published February 2009, SCEC Contribution #1583

The geometry of a fault system can have significant effects on tsunami generation, but most tsunami models to date have not investigated the dynamic processes that determine which path rupture will take in a complex fault system. To gain insight into this problem, we use the 3D finite element method to model the dynamics of a plate boundary/splay fault system. We use the resulting ground deformation as a time-dependent boundary condition for a 2D shallow-water hydrodynamic tsunami calculation. We find that if the stress distribution is homogeneous, rupture remains on the plate boundary thrust. When a barrier is introduced along the strike of the plate boundary thrust, rupture propagates to the splay faults, and produces a significantly larger tsunami than in the homogeneous case. The results have implications for the dynamics of megathrust earthquakes, and also suggest that dynamic earthquake modeling may be a useful tool in tsunami research.

Citation
Elliott, A. J., Dolan, J. F., & Oglesby, D. D. (2009). Evidence from coseismic slip gradients for dynamic control on rupture propagation and arrest through stepovers. Journal of Geophysical Research, 114(B2), B02312. doi: 10.1029/2008JB005969.