HR: 0800h
AN: DI51A-0291 INVITED    [Abstracts]
TI: Source Rupture Process of the 2005 Tarapaca Intermediate Depth Earthquake
AU: * Peyrat, S
EM: peyrat@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4 place Jussieu, Paris, 75252, France
AU: Favreau, P
EM: pfavre@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4 place Jussieu, Paris, 75252, France
AU: De Chabalier, J
EM: dechabal@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4 place Jussieu, Paris, 75252, France
AU: Bouin, M
EM: bouin@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4 place Jussieu, Paris, 75252, France
AB: We investigate the details of the rupture process of the large (Mw 7.7) intermediate-depth earthquake that occurred on 13 June 2005 in the Tarapaca region of the Northern Chile seismic gap, using different data sets and different methods. The high quality and variety of seismic and geodetic data available for this event provided an unprecedented opportunity to study its source in detail. This earthquake is a slab-pull event with down dip extensional source mechanism. The aftershock distribution, determined from a post-seismic temporary array, indicates a sub-horizontal fault plane lying between the upper and lower planes of the double seismic zone. This earthquake was also recorded by a permanent digital strong-motion network operated by the University of Chile. These records have absolute time and high dynamic range so that they contain direct information about the rupture process. We used a systematic, fully nonlinear inversion method based on the neighbourhood algorithm to invert for the kinematic slip distribution using the accelerometric data set. This low frequency inversion provides a relatively smooth image of the rupture history. The kinematic inversion shows that the earthquake occurred by the rupture of two asperities. Based on the kinematic inversion result, we propose dynamic rupture models in order to quantify the dynamic rupture process. We simulate the dynamic rupture process and the strong ground motion using a 3D finite-difference method. In our simulation, dynamic rupture grows under the simultaneous control of initial stress and rupture resistance by friction. We constrain dynamic rupture parameters of the Tarapaca earthquake by simple trial and error. Large intraplate earthquakes in subduction zone are quite common although very few have been studied in detail. These earthquakes occurred at depth where the mechanism by which they are triggered remains poorly understood. Consequently, the determination of source rupture for intermediate intraslab events is important to understand the rupture process of these earthquakes.
DE: 3060 Subduction zone processes (1031, 3613, 8170, 8413)
DE: 7209 Earthquake dynamics (1242)
DE: 7215 Earthquake source observations (1240)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7240 Subduction zones (1207, 1219, 1240)
SC: Study of the Earth's Deep Interior [DI]
MN: 2007 Fall Meeting