HR: 09:15h
AN: S11E-06    [Abstracts]
TI: Energy Partition During In-plane Dynamic Rupture on a Frictional Interface
AU: Needleman, A
EM: needle@brown.edu
AF: Brown University, 182 Hope Street, Providence, RI 02912, United States
AU: * Shi, Z
EM: zheqians@usc.edu
AF: University of Southern California, 3651 Trousdale Pkwy, Los Angeles, CA 90089, United States
AU: Ben-Zion, Y
EM: benzion@usc.edu
AF: University of Southern California, 3651 Trousdale Pkwy, Los Angeles, CA 90089, United States
AB: We study properties of dynamic ruptures and the partition of energy between radiation and dissipative mechanisms using two-dimensional in-plane calculations with the finite element method. The model consists of two identical isotropic elastic media separated by an interface governed by rate- and state-dependent friction. Rupture is initiated by gradually overstressing a localized nucleation zone. Our simulations with model parameters representative of Homalite-100 indicate that different values of parameters controlling the velocity dependence of friction, the strength excess parameter and the length of the nucleation zone, can lead to the following four rupture modes: supershear crack-like rupture, subshear crack-like rupture, subshear single pulse and supershear train of pulses. High initial shear stress and weak velocity dependence of friction favor crack-like ruptures, while the opposite conditions favor the pulse mode. The rupture mode can switch from a subshear single pulse to a supershear train of pulses when the width of the nucleation zone increases. The elastic strain energy released over the same propagation distance by the different rupture modes has the following order: supershear crack, subshear crack, supershear train of pulses and subshear single pulse. The same order applies also to the ratio of kinetic energy (radiation) to total change of elastic energy for the different rupture modes. Decreasing the dynamic coefficient of friction increases the fraction of stored energy that is converted to kinetic energy. In the current study we use model parameters representative of rocks instead of Homalite-100, by modeling recent results of Kilgore et al. (2007) who measured and estimated various energy components in laboratory friction experiments with granite. We are also incorporating into the code ingredients that will allow us to study rupture properties and energy partition for cases with a bimaterial interface and dynamic generation of plastic strain off the fault.
DE: 0545 Modeling (4255)
DE: 0560 Numerical solutions (4255)
DE: 7209 Earthquake dynamics (1242)
DE: 8118 Dynamics and mechanics of faulting (8004)
SC: Seismology [S]
MN: 2007 Fall Meeting