HR: 1340h
AN: S13B-0209    [Abstracts]
TI: Source parameters and GPS deformation of the Mw 7.8 Tarapaca intermediate depth earthquake (Northern Chile) of June 13, 2005.
AU: * Campos, J
EM: jaime@dgf.uchile.cl
AF: Departmento de Geofisica, Universitad de Chili, Blanco Encalada 2002, Casilla 2777, Santiago, 2777 Chile
AU: deChabalier, J
EM: dechabal@ipgp.jussieu.fr
AF: Laboratoire de Sismologie, Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75252 France
AU: Perez, A
EM: adriana@dgf.uchile.cl
AF: Departmento de Geofisica, Universitad de Chili, Blanco Encalada 2002, Casilla 2777, Santiago, 2777 Chile
AU: Bernard, P
EM: bernard@ipgp.jussieu.fr
AF: Laboratoire de Sismologie, Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75252 France
AU: Bonvalot, S
EM: bonvalot@ird.fr
AF: Departmento de Geofisica, Universitad de Chili, Blanco Encalada 2002, Casilla 2777, Santiago, 2777 Chile
AU: Bonvalot, S
EM: bonvalot@ird.fr
AF: IRD/LMTG, 14 avenue E. Belin, Toulouse, 31400 France
AU: Bouin, M
EM: bouin@ipgp.jussieu.fr
AF: Laboratoire de Sismologie, Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75252 France
AU: Charade, O
EM: charade@ipgp.jussieu.fr
AF: Laboratoire de Sismologie, Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75252 France
AU: Cisternas, A
EM: cisternas@dgf.uchile.cl
AF: Departmento de Geofisica, Universitad de Chili, Blanco Encalada 2002, Casilla 2777, Santiago, 2777 Chile
AU: Cisternas, A
EM: cisternas@dgf.uchile.cl
AF: IRD/LMTG, 14 avenue E. Belin, Toulouse, 31400 France
AU: Clevede, E
EM: clevede@ipgp.jussieu.fr
AF: Laboratoire de Sismologie, Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75252 France
AU: Clouard, V
EM: valerie@dgf.uchile.cl
AF: Departmento de Geofisica, Universitad de Chili, Blanco Encalada 2002, Casilla 2777, Santiago, 2777 Chile
AU: Dannoot, R
EM: rachel@dgf.uchile.cl
AF: Departmento de Geofisica, Universitad de Chili, Blanco Encalada 2002, Casilla 2777, Santiago, 2777 Chile
AU: Gabalda, G
EM: gabalda@ird.fr
AF: Departmento de Geofisica, Universitad de Chili, Blanco Encalada 2002, Casilla 2777, Santiago, 2777 Chile
AU: Gabalda, G
EM: gabalda@ird.fr
AF: IRD/LMTG, 14 avenue E. Belin, Toulouse, 31400 France
AU: Kausel, E
EM: ekausel@dgf.uchile.cl
AF: Departmento de Geofisica, Universitad de Chili, Blanco Encalada 2002, Casilla 2777, Santiago, 2777 Chile
AU: Legrand, D
EM: denis@dgf.uchile.cl
AF: Departmento de Geofisica, Universitad de Chili, Blanco Encalada 2002, Casilla 2777, Santiago, 2777 Chile
AU: Lemoine, A
EM: lemoine@ipgp.jussieu.fr
AF: Laboratoire de Sismologie, Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75252 France
AU: Nercessian, A
EM: nercess@ipgp.jussieu.fr
AF: Laboratoire de Sismologie, Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75252 France
AU: Patau, G
EM: patau@ipgp.jussieu.fr
AF: Laboratoire de Sismologie, Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75252 France
AU: Ruegg, J
EM: ruegg@ipgp.jussieu.fr
AF: Laboratoire de Sismologie, Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75252 France
AU: Vilotte, J
EM: vilotte@ipgp.jussieu.fr
AF: Laboratoire de Sismologie, Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75252 France
AB: Teleseismic body wave modeling, time domain moment tensor inversion of regional waveforms, spectral analysis of the P and S-wave pulses, near field data, CMT long period analysis, GPS and SAR data, are used to derive the source parameters of June 13, 2005 (Mw 7.8) Tarapaca intermediate depth earthquake. Its epicentre is located at the NE border of the 1877 (Mw 9.0) earthquake rupture zone. A combined Chilean-French postseismic intervention installed an array around the Tarapaca epicentre (8 short period and 4 broad band). The broadband array extends along a NS, 200 km long profile along the central valley aimed at improving the location and focal mechanisms of aftershocks with waveform inversion. The main shock occurred within the permanent GPS network already installed in 1991-92 by IPGP, DGF and IRD in Northern Chili (22 benchmarks). Following the earthquake, a new survey remade observations. Time domain moment tensor inversion was applied to the regional waveforms of the accelerometer network in Northern Chile and far-field FDSN broadband. These results combined with the distribution of aftershocks following the main shock, indicate a N-S rupture of about 80 km length, a depth distribution between 95 and 115 km depth and the following parameters for the main shock: fault planes (strikes = -6°/156°; dips = 74°/18°; rakes = -99°/61°), depth 105 km and Mo = 4.7 10²⁰ N-m. The regional S-wave spectrum shows a corner frequency of ~ 0.15 Hz indicating a characteristic dimension of ~ 25 km. Estimation of the centroid moment tensor has also been performed from the long-period complex spectra (4-8 mHz) at GEOSCOPE stations. Near field wave form modeling of the closest accelerogram (Pica), twice integrated, has been used to constrain both, focal mechanism and location of the main shock, and gives similar results. The static part of the displacement is constrained by a GPS station at the same site, giving a unique solution for the displacement (dynamic and static). Preliminary results using GPS data from 5 permanent stations in the epicentral area give 5 cm of maximum coseismic displacement, both on vertical and horizontal components. SAR interferometry from the satellite ENVISAT was used to characterize co- and post-seismic displacements. Geodetic models show that a simple elastic homogeneous half-space seems to be sufficient to explain the observed displacements to the first order, in agreement with the seismic wave modeling.
DE: 1207 Transient deformation (6924, 7230, 7240)
DE: 7215 Earthquake source observations (1240)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7240 Subduction zones (1207, 1219, 1240)
SC: Seismology [S]
MN: Fall Meeting 2005