HR: 0800h
AN: S41A-0953    [Abstracts]
TI: Numerical Simulations of 2D In-Plane Ruptures in a Multi-Fault Tri-Material System.
AU: * Brietzke, G
EM: brietzke@geophysik.uni-muenchen.de
AF: Department of Earth and Environmental Sciences, Institute of Geophysics, LMU, Theresienstr. 41, Munich, 80333 Germany
AU: Ben-Zion, Y
EM: benzion@terra.usc.edu
AF: Department of Earth Sciences, USC, 3651 Trousdale Parkway, Los Angeles, CA 90089 United States
AB: Earthquake faults with large slip are likely to bring into contact rocks with different elastic properties. The material near a geological fault is typically observed to be shattered with increased porosity and fluid content, leading to a zone of low seismic velocities, often referred to as fault-zone, between the bounding crustal blocks. Previous work has has shown that ruptures along a material interface have remarkable dynamic properties which are relevant to a number of geophysical and engineering problems. In the present work, we attempt to clarify the conditions for which ruptures that start in the bulk migrate on their own to material interfaces, and evolving properties of such ruptures. We employ a generalized version of the second-order finite-difference code used by Andrews (1973) and Andrews & Ben-Zion (1997) to perform a numerical parameter-space study of two-dimensional in-plane ruptures in a multi-fault tri-material system. We show that material interfaces are favoured locations for rupture propagation and we examine tendencies of initiated ruptures to migrate spontaneously to material interfaces. Ruptures in our work are nucleated by a symmetric bilateral expanding pore pressure source, and may then continue to propagate (or not) along one or several faults. The faults, two of which are material interfaces, are situated equidistant and parallel to each other. Using different nucleation locations, different initial stress, different velocity contrasts, different frictional fault separations, different widths of a low velocity zone, and different number of faults, we examine the range of conditions for which ruptures migrate spontaneously to material interfaces and continue to propagate in a self- sustaining manner. We show simulation results with faults governed by pure Coulomb friction and faults governed by Prakash-Clifton friction, and discuss similarities and differences between the different cases. We also show results of faults governed by Columb friction surrounded by a viscoelastic media.
DE: 7260 Theory and modeling
DE: 7200 SEISMOLOGY
DE: 7209 Earthquake dynamics and mechanics
SC: Seismology [S]
MN: 2004 AGU Fall Meeting