HR: 1340h
AN: T33C-0580    [Abstracts]
TI: Elements of the Seismic Structure and Activity of the Lesser Antilles Subduction Zone (Guadeloupe and Martinique Islands) from the SISMANTILLES Seismic Survey
AU: * Laigle, M
EM: laigle@ipgp.jussieu.fr
AF: Sismologie, Institut de Physique du Globe de Paris, Case 89, 4 Place Jussieu, PARIS Cedex5, Fra 75252 France
AU: Roux, E
EM: eroux@ipgp.jussieu.fr
AF: Sismologie, Institut de Physique du Globe de Paris, Case 89, 4 Place Jussieu, PARIS Cedex5, Fra 75252 France
AU: Sapin, M
EM: sapin@ipgp.jussieu.fr
AF: Sismologie, Institut de Physique du Globe de Paris, Case 89, 4 Place Jussieu, PARIS Cedex5, Fra 75252 France
AU: Hirn, A
EM: hirn@ipgp.jussieu.fr
AF: Sismologie, Institut de Physique du Globe de Paris, Case 89, 4 Place Jussieu, PARIS Cedex5, Fra 75252 France
AU: De Voogd, B
EM: beatrice.devoogd@univ-pau.fr
AF: Universit‚ de Pau, Dpt des sciences de la Terre, B.P. 1155, Pau Cedex, Fra 64013 France
AU: Charvis, P
EM: charvis@obl-vlfr.fr
AF: IRD-G‚osciences Azur, Quai de la Darse, Villefranche sur Mer, Fra 06230 France
AU: Hello, Y
EM: Yann.Hello@geoazur.obs-vlfr.fr
AF: IRD-G‚osciences Azur, Quai de la Darse, Villefranche sur Mer, Fra 06230 France
AU: Murai, Y
EM: murai@eos.hokudai.ac.jp
AF: Institute of Seismology and Volcanology, N10, W8, Sapporo, Hokka‹do, jap 060-0810 Japan
AU: Nishimura, Y
EM: nishi@eos.hokudai.ac.jp
AF: Institute of Seismology and Volcanology, N10, W8, Sapporo, Hokka‹do, jap 060-0810 Japan
AU: Shimamura, H
EM: shima@eos.hokudai.ac.jp
AF: Institute of Seismology and Volcanology, N10, W8, Sapporo, Hokka‹do, jap 060-0810 Japan
AU: Galve, A
EM: galve@ ipgp.jussieu.fr
AF: Institut de Ciencies de la Terra "J. Almera", c/ LLuis Sole Sabaris s/n, Barcelona, spa 08028 Spain
AU: Lepine, J
EM: lepine@ ipgp.jussieu.fr
AF: Sismologie, Institut de Physique du Globe de Paris, Case 89, 4 Place Jussieu, PARIS Cedex5, Fra 75252 France
AU: Lebrun, J
EM: jflebrun@univ-ag.fr
AF: Universit‚ des Antilles et de la Guyane - Dpt de G‚ologie, Campus de Fouillole, BP 592, Pointe … Pitre CEDEX, fra 97159 Guadeloupe
AU: Diaz, J
EM: jdiaz@ija.csic.es
AF: Institut de Ciencies de la Terra "J. Almera", c/ LLuis Sole Sabaris s/n, Barcelona, spa 08028 Spain
AU: Gallart, J
EM: jgallart@ija.csic.es
AF: Institut de Ciencies de la Terra "J. Almera", c/ LLuis Sole Sabaris s/n, Barcelona, spa 08028 Spain
AU: Beauducel, F
EM: beauducel@ovsg.univ-ag.fr
AF: OVSG - IPGP, Le Houelmont, GOURBEYRE, fra 97113 Guadeloupe
AU: Viode, J
EM: viode.jp@wanadoo.fr
AF: OVMP - IPGP Observatoire Volcanologique de la Montagne Pel‚e, Morne des Cadets Fonds St Denis, Saint-Pierre, fra 97250 Martinique
AB: The Lesser Antilles is an active subduction zone, prone to future major earthquakes as it has experienced in the past with the occurrence in 1843 of a M>7.5 probably mega-thrust earthquake that destroyed Pointe-a-Pitre city on Guadeloupe Island. The SISMANTILLES project was carried out at a regional scale for a first reconnaissance of the seismic structure and activity from northern Guadeloupe to Martinique islands. The project focused more particularly on the detection, mapping and characterisation of the potentially seimogenic part of the interplate subduction fault. The french N/O Nadir vessel acquired 2500 km of deep-penetration multichannel reflection seismic (MCS) profiles. Up to 37 3-components Ocean Bottom Seismometers (OBS) were deployed offshore over several weeks together with a set of 3-components broadened-band stations on the islands (Martinique, Dominica, Guadeloupe and Antigua). These instruments recorded continuously both the MCS shots that provided wide angle reflexion and refraction (WARR) data as well as the local, regional and teleseismic earthquakes. On MCS profiles, reflections from the top of the subducting oceanic crust and decollement can be followed down to several km depth beneath the thick accretionary prism. Detailed velocity analysis provided depth structural sections that are used as an input for the forward modeling of WARR data. Thanks to these data, we can constrain on 3 transects to the arc, the part where the forearc deep crust is in contact with the subducting oceanic plate, considered as a proxy for the seismogenic part. Its location with respect to the deformation front and the volcanic arc and its downdip size appear significantly variable along the arc. The local earthquakes now reliably located in map and depth thanks to the high-quality P and S observations of the OBS network can be discussed with respect to these imaged structures. Local earthquakes P & S tomography as well as receiver functions analysis will bring more constraints on the deeper structure beneath the arc crust and thus on the downdip limit of the seismogenic portion of the subduction interplate.
DE: 0468 Natural hazards
DE: 1734 Seismology
DE: 3025 Marine seismics (0935, 7294)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7240 Subduction zones (1207, 1219, 1240)
SC: Tectonophysics [T]
MN: Fall Meeting 2005