HR: 08:40h
AN: S51F-03 INVITED     [Abstracts]
TI: Dynamic rupture simulations of large events on the San Andreas fault in the San Francisco Bay area using realistic nonplanar fault geometry
AU: * Aagaard, B T
EM: baagaard@usgs.gov
AF: US Geological Survey, USGS MS977 345 Middlefield Rd, Menlo Park, CA 94025 United States
AB: I am exploring the effect of nonplanar fault geometry on earthquake source dynamics for M7.5+ events on the San Andreas fault in the San Francisco Bay area. The geologic structure, which includes the fault surfaces, topography, and material properties, is defined by the USGS Bay Area Velocity Model 05.0.0. The fault geometries in the velocity model are constrained by geologic mapping, geophysical inversions, and double-difference relocations of the seismicity. Discretizing the domain using tetrahedral finite elements allows the finite-element mesh to conform to the complex geometry defined by the topography and fault surfaces; this permits simulation of earthquakes using dynamic (spontaneous) ruptures. I compare ground motions from dynamic ruptures with those from a kinematic rupture with uniform slip and rupture speed. The dynamic rupture simulations include scenarios with uniform fault shear stress (not realistic but an important test case) and a uniform regional shear stress field (more realistic). The results show that nonplanar fault geometry and lateral variations in the material properties cause complex variations in rupture behavior and the distribution of shaking. As expected, the nonplanar geometry has the greatest effect for the case of a uniform regional shear stress field.
DE: 7209 Earthquake dynamics (1242)
DE: 7212 Earthquake ground motions and engineering seismology
SC: Seismology [S]
MN: Fall Meeting 2005