HR: 16:30h
AN: G24A-05    [Abstracts]
TI: Comparing geological and geodetic deformation on megathrust
AU: * Avouac, J
EM: avaouc@gps.caltecch.edu
AF: California Institute of Technology, 1200 E. California MC 100-23, Pasadena, CA 91125 United States
AU: Perfettini, H
EM: perfetti@lmtg.obs-mip.fr
AF: Institut de Recherche pour le Developpment, Laboratoire des Mecanismes de Transferts en Geologie, Toulouse, France
AU: Bollinger, L
EM: bollinge@dase.bruyeres.cea.fr
AF: CEA/DAM/DASE/LDG, BP12 , 91680 BRUYERES LE CH, France
AB: The `seismic cycle' concept assumes that earthquakes rupture fault portions that remain locked over the period between recurring earthquakes. Each event would release some the stresses accumulated in the interseismic period. This kinematic description offers a convenient and quite successful framework to integrate geodetic and geological observations. In this presentation we will overview geodetic, geological and geophysical observations made in the context of intracontinental thrust faults in the Himalaya and Taiwan and discuss their implications regarding faults rheology and the mechanics of the seismic cycle. We will in particular discuss the role of temperature, fluids, and stress transfer in governing strain and seismicity over the seismic cycle. We will show in particular that background seismicity is relatively well explained from stress build up in the interseismic period and that reloading of the upper brittle crust, due to postseismic afterslip and viscous relaxation is a viable mechanism to explain jointly geodetic data and the decay rate of aftershocks following large thrust event, such as for example the Chichi earthquake. The model is also used to assess eventual non-stationary of strain in the interseismic period. Depending on the viscosity and thickness of the viscous shear zone at depth, stress transfers during the seismic cycle may indeed lead to significant variations of interseismic strain that could be detected from comparing geodetic rates and geological rates.
DE: 1206 Crustal movements--interplate (8155)
DE: 1242 Seismic deformations (7205)
SC: Geodesy [G]
MN: 2005 Joint Assembly