HR: 0830h
AN: S41D-0126    [PDF]
TI: The 2002-2003 CHARSME Experiment : Preliminary Results
AU: Pardo, M
EM: mpardo@dgf.uchile.cl
AF: Departamento de Geof\'{i}sica, Universidad de Chile, Blanco Encalada 2085, SANTIAGO, 1 Chile
AU: * Monfret, T
EM: monfret@geoazur.unice.fr
AF: UMR G\'{e}osciences Azur - IRD/UNSA, 250, rue Albert Einstein, VALBONNE, 06560 France
AU: Vera, E
EM: evera@dgf.uchile.cl
AF: Departamento de Geof\'{i}sica, Universidad de Chile, Blanco Encalada 2085, SANTIAGO, 1 Chile
AU: Yanez, G
EM: gyane003@stgo.codelco.cl
AF: Codelco-Chile, Teatinos 258 Piso 7, SANTIAGO, 1 Chile
AU: BONVALOT, S
EM: bonvalot@dgf.uchile.cl
AF: Departamento de Geof\'{i}sica, Universidad de Chile, Blanco Encalada 2085, SANTIAGO, 1 Chile
AU: BONVALOT, S
EM: bonvalot@dgf.uchile.cl
AF: IRD Mission-Chili, 264 Rom\'{a}n D\'{i}az, Providencia, SANTIAGO, 1 Chile
AU: Gabalda, G
EM: gabalda@dgf.uchile.cl
AF: Departamento de Geof\'{i}sica, Universidad de Chile, Blanco Encalada 2085, SANTIAGO, 1 Chile
AU: Gabalda, G
EM: gabalda@dgf.uchile.cl
AF: IRD Mission-Chili, 264 Rom\'{a}n D\'{i}az, Providencia, SANTIAGO, 1 Chile
AU: Eisenberg, A
EM: aeisenbe@dgf.uchile.cl
AF: Departamento de Geof\'{i}sica, Universidad de Chile, Blanco Encalada 2085, SANTIAGO, 1 Chile
AU: TRIEP, E
EM: triep@idecom.unsj.edu.ar
AF: Universidad Nacional de San Juan, Meglioli 1160 Sur, SAN JUAN, 1 Argentina
AU: Hustedt, B
EM: hustedt@geoazur.unice.fr
AF: Departamento de Geof\'{i}sica, Universidad de Chile, Blanco Encalada 2085, SANTIAGO, 1 Chile
AU: Bethoux, N
EM: nbethoux@obs-vlfr.fr
AF: Departamento de Geof\'{i}sica, Universidad de Chile, Blanco Encalada 2085, SANTIAGO, 1 Chile
AB: From Nov. 2002 to March 2003, the CHARSME project (CHile ARgentina Seismological Measurement Experiment) took place in Chile and Argentina in order to analyze the regional seismotectonic characteristics and to map the change of the subducted Nazca plate from a flat-slab to an inclined geometry. Local seismological and gravimetric data were collected. A seismic network of 30 portable broadband stations, continuous recording, was deployed between 31.5$\deg$S-34$\deg$S and 71$\deg$W-67$\deg$W, in addition to permanent stations on the Chilean side belonging to the University of Chile network. About 7200 earthquakes were detected during the experiment, however, only about the 50% have been located till now. Most of them are related with the subduction of the Juan Fernandez Ridge which takes place at the southern part of the flat-slab zone. There are also several crustal shallow events with well constrained focal mechanism, mainly located in the Andes Cordillera. These focal mechanisms confirm that most of the superficial deformation is compressive and due to shortening. Some effort has to be made to correlate this shallow activity with geological features. With the available located seismicity, we still can not have a precise image of the transition zone between the two subduction geometries, but we hope that with a local tomography we can achieve this goal. In parallel with the seismological experiment, two NS gravimetric profiles of 500 and 300 km long were performed with 2 portable gravimeters and 3 bi-frenquency GPS stations. These profiles crossed the transition zone of the slab geometry. From preliminary data, we found a variation of the gravity field between points situated above the flat-slab and inclined subduction. This variation can be generated by an asthenospheric wedge present underneath the inclined geometry and absent in the case of the flat one.
DE: 7230 Seismicity and seismotectonics
SC: Seismology [S]
MN: 2003 Fall Meeting