HR: 16:00h
AN: S34A-01 INVITED     [Abstracts]
TI: Rupture dynamics of a geometrically complex fault
AU: * Madariaga, R I
EM: madariag@geologie.ens.fr
AF: Laboratoire de Géologie, Laboratoire de Géologie Ecole Normale Supérieure 24 rue Lhomond, Paris Cedex 05, 75251 France
AU: Ampuero, J
EM: ampuero@erdw.ethz.ch
AF: Institute of Geophysics Seismology and Geodynamics, ETH Hönggerberg (HPP) CH-8093 Zürich Switzerland e-mail:, Zurich, CH-8093 Switzerland AB: We study the propagation of a two dimensional antiplane rupture along a complex geometrical fault containing a series of kinks of different angles and intervals between the kinks. Numerical solutions are obtained using the spectral element methods developed by Vilotte, Ampuero and Komatisch. We model both periodically kinked and simple versions of randomly kinked faults. We compare our simulations with the results obtained for rupture propagation along flat faults. We find that geometrically complex differ substantially from flat faults. First, complex faults emit high frequency radiation of ω^-2 type every time they encounter geometrical discontinuities, this produces a strong damping of rupture propagation. Second, the average rupture speed along the overall direction of the fault is substantially reduced and, depending on the nature of the geometrical discontinuities, ruptures may be easily stopped. Energy release rates computed assuming that the fault is flat increase as the fault becomes increasingly complex. The stress field around the fault may be described as a corridor of strongly variable stress with patches of stress increase and decrease even if the slip on the fault is continuous. Contrary to flat faults, earthquake propagation leaves behind a complex final state of stress. Our model confirms the experimental findings of many authors who worked on high speed mode I fracture.
DE: 0545 Modeling (4255)
DE: 7209 Earthquake dynamics (1242)
SC: Seismology [S]
MN: Fall Meeting 2005