HR: 0800h
AN: S41A-0941    [Abstracts]
TI: Dynamic Earthquake Rupture Modeling With Stochastic Fault Stress
AU: Mai, P M
EM: mai@ethz.ch
AF: Institute of Geophysics, ETH Zurich, Schafmattstr. 30, Zurich, 8093 Switzerland
AU: * Ripperger, J
EM: ripperger@ethz.ch
AF: Institute of Geophysics, ETH Zurich, Schafmattstr. 30, Zurich, 8093 Switzerland
AB: We investigate how the evolution of dynamic earthquake rupture is controlled by heterogeneous stress distributions on the fault plane. A 3D finite difference code is used to model rupture on a single vertical fault plane obeying a slip-weakening friction law. The friction parameters (critical slip-weakening distance, coefficients of friction) are kept homogeneous over the fault plane, whereas the distributions of shear and normal stress are modeled as spatial random fields with predefined wavenumber spectra. We test different parametrizations for the stress distributions, being either purely fractal (with variable fractal dimension) or following a von Karman autocorrelation function (with variable correlation lengths). We also investigate how the degree of correlation between shear and normal stress affects the dynamic rupture calculations. Ruptures are initiated at randomly chosen hypocenters and their evolution is tracked in space and time, allowing us to study in detail the conditions required for rupture to grow from small into large events. In our approach we repeatedly use "leftover" stress distributions from previous simulations for which no large ruptures have occured, allowing us to also examine statistical properties (e.g. frequency-size distributions) of the generated earthquake sequences.
DE: 7260 Theory and modeling
DE: 7209 Earthquake dynamics and mechanics
DE: 3230 Numerical solutions
DE: 3250 Fractals and multifractals
SC: Seismology [S]
MN: 2004 AGU Fall Meeting