HR: 0800h
AN: S31C-0558    [Abstracts]
TI: Wide angle seismic refraction imaging of the Northern Sumatra Subduction Zone
AU: * Chauhan, A P
EM: chauhan@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75252, France
AU: Singh, S C
EM: singh@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75252, France
AU: Carton, H
EM: hcarton@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, Marine Geology and Geophysics 61 Route 9W - PO Box 1000, Palisades, NY, 10964-8000, United States
AU: Hananto, N D
EM: hananto@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75252, France
AU: Klingelhoefer, F
EM: Frauke.Klingelhoefer@ifremer.fr
AF: Ifremer, BP 70, Plouzane, 29280, France
AU: Dessa, J
EM: dessa@geoazur.obs-vlfr.fr
AF: Geosciences Azur, BP 48, Villefranche sur Mer, 06235, France
AU: Permana, H
EM: harperhp@yahoo.com
AF: LIPI, Jl. Sangkuriang, Bandung, 40132, Indonesia
AU: Graindorge, D
EM: David.Graindorge@univ-brest.fr
AF: University Brest, Place Nicolas Copernic, Plouzane, 29280, France
AU: Dean, S
EM: smd9@noc.soton.ac.uk
AF: NOC, European Way, Southampton, SO14 3ZH, United Kingdom
AU: White, N
EM: nwhite@esc.cam.ac.uk
AF: Department of Earth Sciences, University of Cambridge Madingley Road, CAMBRIDGE, CB3 0EZ, United Kingdom
AU: Chaubey, A
EM: chaubey@darya.nio.org
AF: NIO, Dona Paula, Goa, 403 004, India
AU: Shankar, U
EM: umashankar_ngri@yahoo.com
AF: NGRI, Uppal Road, Hyderabad, 500 007, India
AU: Galih, D
EM: dodi293@yahoo.com
AF: LIPI, Jl. Sangkuriang, Bandung, 40132, Indonesia
AU: Royle, G
EM: royle@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75252, France
AU: Aryawan, K
EM: igka2000@yahoo.com
AF: DESDM, Jl. Dr. Junjunan 236, Bandung, 40174, Indonesia
AU: Laesanpura, A
EM: laesampu@gf.itb.ac.id
AF: ITB, Jl. Ganesha 10, Bandung, 40132, Indonesia
AU: Prihantono, J
AF: BRKP-DKP, Jl. MT Haryono Kav 52-53, Jakarta, 12770, Indonesia
AB: Two deep penetrating wide angle seismic refraction profiles were acquired during the SUMATRA-OBS cruise offshore Sumatra, to image the subsurface in the zone of maximum co-seismic slip for the great Sumatra- Andaman earthquake of December 2004. Here we present the 2-D velocity image of the subsurface obtained by traveltime tomographic inversion of the northern profile. This line was shot twice using airguns onboard R/V Marion Dufresne (~8260 cu inch) and the one onboard Western-Geco/Schlumberger vessel the Searcher (~10000 cu inch) with much denser shot spacing. The velocity image spanning a ~520 km long profile almost at orthogonal orientation to the trench, is obtained by the inversion of about ~30000 traveltime picks made on the 56 ocean bottom seismometers (OBSs) that were deployed along the profile. The velocity model depicts the rather thin (~4.5-6.0 km) Indo-Australian oceanic plate in the region, subducting underneath the Sunda plate at an angle of about 8-10°. The subducting slab is overlain by thick volume of the evolved accretionary complex for about 150 km, followed with the system of Aceh basin in forearc region and the volcanic arc domain further east. The high velocity structure just east underneath of the Aceh basin appears to be of continental origin and might be a result of the complex tectonic history of the region. On the eastern end of the line the continental crust with thickness of about 12-15 km appears to be thinned by the pull-apart extension activity of the various branches of Sumatra fault. The experiment was conducted in conjunction with the acquisition of coincident seismic reflection lines by the Western-Geco/Schlumberger's "Searcher" seismic vessel. Future work aims at obtaining a depth migrated subsurface image of the coincident seismic reflection profile WG2 using this velocity model, to further constrain the geometry and structure of this highly active subduction zone.
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 7270 Tomography (6982, 8180)
SC: Seismology [S]
MN: 2007 Fall Meeting