HR: 0800h
AN: U11A-0822    [Abstracts]
TI: Evidence from in situ pore pressure monitoring of submarine slope failures generated by the December 26, 2004 Great Sumatra Earthquake
AU: Sultan, N
EM: nabil.sultan@ifremer.fr
AF: Ifremer Centre de Brest, B.P. 70, Plouzane, 29280 France
AU: Cattaneo, A
U11A-0822 AF: Ifremer Centre de Brest, B.P. 70, Plouzane, 29280 France
AU: * Sibuet, J
EM: jcsibuet@ifremer.fr
AF: Ifremer Centre de Brest, B.P. 70, Plouzane, 29280 France
AB: The scientific ® Sumatra Aftershocks ¯ cruise was performed onboard the French R/V Marion Dufresne during summer 2005 (July, 14 - August, 9), within a relatively short delay from the Great Sumatra Earthquake (26 December 2004). One of the main aims of the cruise was to enquire about submarine mass wasting processes possibly associated with recent earthquake events. Within the whole investigated area from the trench up to the accretionary prism and the continental slope flanking the Aceh forearc basin, the swath bathymetric data acquired during the cruise have only shown the occurrence of relatively minor scars and deposits with a `fresh' aspect corresponding to likely recent slope failures. The fact that no huge submarine landslide was found could be explained with the high frequency of high-magnitude seismic events occurring in the study area. This recurrence of events might favor the presence of numerous very small-scale rather than a few large landslides. Core MD05-2975, recovered on the slope of the wedge, close to the trench and close to a small landslide already identified by the HMS Scott, indicates the existence of remoulded sediment. The in situ pore pressure monitoring at the same site, using a piezometer recently developed by Ifremer, demonstrates that an excess pore pressure was generated by a recent earthquake event. Although we obtained indication of recent seafloor deformation at a single site, we suspect, based on the new morphological data, that similar phenomena might have occurred throughout the margin. To verify if slope failures have contributed or not to the trigger of the devastating tsunami of December, 26, 2004, more piezometer measurements are needed together with a quantitative evaluation of morphological parameters of landslides.
DE: 8104 Continental margins: convergent
SC: Union [U]
MN: Fall Meeting 2005