HR: 1340h
AN: S13B-1305    [Abstracts]
TI: Coseismic Stress Changes of the September 28, 2004 M=6 Parkfield Earthquake From Variation of Recurrence Time of Microearthquakes
AU: Marsan, D
EM: david.marsan@univ-savoie.fr
AF: LGIT, Universite de Savoie, Le Bourget du Lac, 73376, France
AU: * Lengline, O
EM: olivier.lengline@univ-savoie.fr
AF: LGIT, Universite de Savoie, Le Bourget du Lac, 73376, France
AB: We relocated a set of earthquakes that occurred between January 1984 and May 2007 in the vicinity of Parkfield, California. Space-time correlations performed on earthquakes that occurred before the September 28, 2004, M=6 earthquake reveal : (1) a triggering mechanism that dominates the dynamics over a period of about 10 days, (2) a cut-off in triggering at < 1 rupture length but with no clear-cut shadow and (3) an enhanced triggering at 100- 1000 days (i.e. multiplet recurrence times). The unique framework of the Parkfield seismicity (precise earthquake relocations, repeaters) allows to estimate stress changes at a very small scale. Computation of the clock advance caused by the M=6 mainshock for individual multiplet leads to an estimation of the stress changes at the scale of the multiplet size. This reveals insight of the stress heterogeneities on the fault plane caused by the 2004 mainshock.
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
SC: Seismology [S]
MN: 2007 Fall Meeting