HR: 17:15h
AN: S24A-06    [Abstracts]
TI: Nonlinear Dynamics, Granular Media and Dynamic Earthquake Triggering
AU: * Johnson, P A
EM: paj@lanl.gov
AF: Geophysics Group EES-11, , Los Alamos National Laboratory of the University of California, MS D443, Los Alamos, NM 87545 United States
AU: * Johnson, P A
EM: paj@lanl.gov
AF: Laboratoire de Physique des Mat‚riaux Divis‚s et des Interfaces, CNRS UMR 8108, Bƒtiment Lavoisier - Cit‚ Descartes, 5 boulevard Descartes - Champs sur Marne, Marne la Vallee, cedex 2 France
AU: Jia, X
EM: jia@univ-mlv.fr
AF: Laboratoire de Physique des Mat‚riaux Divis‚s et des Interfaces, CNRS UMR 8108, Bƒtiment Lavoisier - Cit‚ Descartes, 5 boulevard Descartes - Champs sur Marne, Marne la Vallee, cedex 2 France
AB: The physical origin of dynamic triggering of earthquakes remains one of the least understood aspects of earthquake processes. Here we show that the dynamic, elastic-nonlinear behavior of fault gouge under the influence of a seismic wave may be responsible for earthquake triggering. We base our hypothesis on recent dynamic experiments conducted in granular media, a surrogate for fault gouge. Our experiments show that, under relatively small effective pressures that one could expect in the fault zone, dynamic waves with strain amplitudes known to trigger earthquakes cause the material modulus to abruptly decrease. The modulus decrease results in material weakening via a simple deformation and instability model. Our conceptual model is that seismic waves from a distant earthquake impinge on a fault that is critically stressed, temporarily decreasing the gouge modulus. The modulus decrease corresponds to an abrupt material strength decrease sufficient to induce fault slip.
DE: 7280 Volcano seismology (8419)
DE: 7299 General or miscellaneous
DE: 7209 Earthquake dynamics and mechanics
DE: 7215 Earthquake parameters
SC: Seismology [S]
MN: 2004 AGU Fall Meeting