HR: 1340h
AN: S43A-1068    [Abstracts]
TI: Three-Dimensional Simulations of Spontaneous Earthquake Sequences
AU: * Liu, Y
EM: yil@caltech.edu
AF: Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125 United States
AU: Lapusta, N
EM: lapusta@caltech.edu
AF: Division of Geological and Planetary Sciences and Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125 United States
AB: Simulations of spontaneous earthquakes in three-dimensional (3D) models enjoy a lot of interest, because of their ability to clarify earthquake physics. We are developing a procedure for simulating sequences of dynamic events on a fault subjected to rate and state friction and slow tectonic loading. The algorithm, extended from the 2D study by Lapusta et al. (2000), allows us to resolve all stages of every earthquake in a single computational procedure, including nucleation process, dynamic rupture propagation, post-seismic deformation, and slow creeping slippage throughout the loading period. Simulating earthquake sequences is quite challenging even in 2D models due to a variety of temporal and spatial scales. Switching to 3D requires overcoming new theoretical and computational challenges. We have started our 3D simulations by considering a buried seismogenic region with steady-state velocity-weakening properties surrounded by a steady-state velocity-strengthening region that stably slips (creeps) under loading. The seismogenic region is 30 km long and 15 km deep. We find that, for large characteristic distances of the rate and state friction, the model produces large, model-spanning quasi-periodic earthquakes. We also find that changing the model in the direction of decreasing inertial effects slows down the rupture propagation, decreases the peak slip velocities, and reduces the recurrence period of the earthquakes. These results are consistent with the previous 2D studies. We will report on our current work that concentrates on (1) simulations in a fault model with simplified representation of a free surface and (2) further developments in the methodology, to enable 3D studies of more realistic model parameters. We plan to use the developed methodology to study earthquake nucleation, dynamic propagation, post-seismic slip, and their interaction, concentrating first on small event clustering on rheological transitions and interaction of earthquake sequences with fault heterogeneities.
DE: 0560 Numerical solutions (4255)
DE: 7209 Earthquake dynamics (1242)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 8020 Mechanics, theory, and modeling
DE: 8118 Dynamics and mechanics of faulting (8004)
SC: Seismology [S]
MN: Fall Meeting 2005