HR: 1340h
AN: S53A-1076    [Abstracts]
TI: Dynamic Rupture on a Bimaterial Interface Governed by Slip-weakening Friction
AU: * Shi, Z
EM: zheqians@usc.edu
AF: University of Southern California, 3651 Trousdale Pkwy, ZHS 117, Los Angeles, CA 90089 United States
AU: Ben-Zion, Y
EM: benzion@usc.edu
AF: University of Southern California, 3651 Trousdale Pkwy, ZHS 117, Los Angeles, CA 90089 United States
AB: We perform 2D finite-difference calculations of mode II rupture along a bimaterial interface governed by slip-weakening friction, with the goal of clarifying rupture properties in such cases and the conditions leading to the development of unilateral wrinkle-like pulses. The simulations begin with an imposed bilateral rupture in a limited source region. Rupture properties outside the imposed source are examined for ranges of values of the degree of material contrast γ across the fault, the difference between static f_s and dynamic f_d coefficients of friction, and the difference between static friction and initial shear stress. The results show that mode II rupture evolves with propagation distance along a bimaterial interface, for broad ranges of realistic conditions, to a unilateral wrinkle-like pulse in the direction of slip on the complaint side of the fault. These conditions span in our calculations the ranges f_s - f_{d < 0.4 and γ > 2-5%. When the difference between the static friction and initial shear stress is smaller, the evolution to unilateral wrinkle-like pulses occurs for smaller values of γ. The amount of slip increases with propagation distance, due to the incorporation of slip-wakening friction, in contrast to earlier results based on Coulomb and Prakash-Clifton friction laws with slip-independent coefficient. In all cases leading to wrinkle-like pulses, the rupture velocity in the preferred (+) propagation direction is V_r}⁺ ~ C_GR, where C_{GR is the generalized Rayleigh wave speed. Simulations with imposed rupture speed in the source region close to the slower {P} wave speed {P}^- can excite, in addition to the primary wrinkle-like pulse in the preferred direction with V_r}⁺ ~ C_GR, a weak pulse in the opposite (-) direction with V_r^- ~ {P}^-. In some cases leading to bilateral crack-like propagation (e.g., f_s - f_{d = 0.7), the rupture velocities in the opposite directions are V_r}⁺ ~ {P}⁺ (the faster {P} wave speed) and V_r^- ~ {P}^-, with the initial supershear crack front in the + direction followed by a pulse with V_r⁺ ~ C_GR.
DE: 7209 Earthquake dynamics (1242)
DE: 7290 Computational seismology
DE: 8004 Dynamics and mechanics of faulting (8118)
DE: 8020 Mechanics, theory, and modeling
SC: Seismology [S]
MN: Fall Meeting 2005