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Registros recuperados: 5
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High-resolution seismic imaging in deep sea from a joint deep-towed/OBH reflection experiment: application to a Mass Transport Complex offshore Nigeria ArchiMer
Ker, Stephan; Marsset, Bruno; Garziglia, Sebastien; Le Gonidec, Y.; Gibert, D.; Voisset, Michel; Adamy, J..
P>We assess the feasibility of high-resolution seismic depth imaging in deep water based on a new geophysical approach involving the joint use of a deep-towed seismic device (SYSIF) and ocean bottom hydrophones (OBHs). Source signature measurement enables signature deconvolution to be used to improve the vertical resolution and signal-to-noise ratio. The source signature was also used to precisely determine direct traveltimes that were inverted to relocate source and receiver positions. The very high accuracy of the positioning that was obtained enabled depth imaging and a stack of the OBH data to be performed. The determination of the P-wave velocity distribution was realized by the adaptation of an iterative focusing approach to the specific...
Tipo: Text Palavras-chave: Controlled source seismology; Seismic tomography; Acoustic properties; Submarine landslides; Atlantic Ocean.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00044/15510/12959.pdf
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Investigation of a possible submarine landslide at the Var delta front (Nice continental slope, southeast France) ArchiMer
Sultan, Nabil; Savoye, Bruno; Jouet, Gwenael; Leynaud, Didier; Cochonat, Pierre; Henry, P.; Stegmann, Sylvia; Kopf, Achim.
The Var prodelta progrades across a straight, narrow shelf (less than 2 km wide) with a very steep continental slope reaching locally more than 30 degrees. Historically, the Var delta front is sadly famous for the 1979 catastrophic submarine landslide that resulted in several casualties and infrastructural damage. Geotechnical and geophysical investigations carried out in late 2007 to the east of the 1979 landslide scar provide evidence for the possible occurrence of a new important sedimentary collapse and submarine landslide. Geophysical data acquired in the area show the presence of several seafloor morphological steps rooted to shallow subsurface seismic reflections. Moreover, in situ piezocone measurements demonstrate the presence of several shear...
Tipo: Text Palavras-chave: CPTu; Gassy soil; Piezocone; Shear zone; Submarine landslides.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00004/11481/8096.pdf
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Morphology, distribution and origin of recent submarine landslides of the Ligurian Margin (North-western Mediterranean): some insights into geohazard assessment ArchiMer
Migeon, Sebastien; Cattaneo, Antonio; Hassoun, Virginie; Larroque, Christophe; Corradi, Nicola; Fanucci, Francesco; Dano, Alexandre; De Lepinay, Bernard Mercier; Sage, Francoise; Gorini, Christian.
Based on new multibeam bathymetric data, seismic-reflection profiles and side-scan sonar images, a great number of submarine failures of various types and sizes was identified along the northern margin of the Ligurian Basin and characterized with 3 distinct end-members concerning their location on the margin, sedimentary processes and possible triggering mechanisms. They include superficial landslides mainly located in the vicinity of the main mountain-supplied rivers and on the inner walls of canyons (typically smaller that 10(8) m(3) in volume: Type 1), deep scars 100-500 m high along the base of the continental slope (Type 2), and large-scale scars and Mass Transport Deposits (MTDs) affecting the upper part of the slope (Type 3 failures). The MTDs are...
Tipo: Text Palavras-chave: Ligurian Sea; Submarine landslides; Seafloor morphology; Seismic-reflection profiles; Side-scan sonar.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00043/15387/14028.pdf
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Searching for the seafloor signature of the 21 May 2003 Boumerdès earthquake offshore central Algeria ArchiMer
Cattaneo, Antonio; Babonneau, Nathalie; Ratzov, G.; Dan-unterseh, G.; Yelles, K.; Bracene, R.; De Lepinay, B. Mercier; Boudiaf, A.; Deverchere, Jacques.
Shaking by moderate to large earthquakes in the Mediterranean Sea has proved in the past to potentially trigger catastrophic sediment collapse and flow. On 21 May 2003, a magnitude 6.8 earthquake located near BoumerdSs (central Algerian coast) triggered large turbidity currents responsible for 29 submarine cable breaks at the foot of the continental slope over similar to similar to 150 km from west to east. Seafloor bathymetry and backscatter imagery show the potential imprints of the 2003 event and of previous events. Large slope scarps resulting from active deformation may locally enhance sediment instabilities, although faults are not directly visible at the seafloor. Erosion is evident at the foot of the margin and along the paths of the numerous...
Tipo: Text Palavras-chave: Western mediterranean sea; Cascadia subduction zone; Turbidity current; Zemmouri earthquake; Sedimentary processes; Submarine landslides; Northern algeria; Margin; Gps; Boundary.
Ano: 2012 URL: http://archimer.ifremer.fr/doc/00098/20959/18571.pdf
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The tsunami signature on a submerged promontory: the case study of the Atacames Promontory, Ecuador ArchiMer
Ioualalen, Mansour; Ratzov, G.; Collot, Jean-yves; Sanclemente, E..
P>Shelf promontories exhibit very specific bathymetric features with regards to tsunamis. Because of their submerged cape morphology, a potential tsunami generated seawards of the promontory will exhibit a specific mode of propagation and coastal impact. To identify this peculiar tsunami signature, the Atacames Promontory, Ecuador, was chosen as a case study (another example is the shelf of the Nile delta, Egypt). The area is tectonically very active, hosts earthquakes among the most powerful recorded, as well as areas of slope instabilities that have triggered significant submarine landslides in the past (several cubic kilometres of volume). Both types of events are likely to be tsunamigenic. To examine the tsunami behaviour at the coastal area of the...
Tipo: Text Palavras-chave: Tsunamis; Site effects; Wave propagation; Submarine landslides; South America.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00200/31101/29509.pdf
Registros recuperados: 5
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