High-resolution seismic imaging in deep sea from a joint deep-towed/OBH reflection experiment: application to a Mass Transport Complex offshore Nigeria

Type Article
Date 2010-09
Language English
Author(s) Ker StephanORCID1, 3, Marsset Bruno3, Garziglia Sebastien3, Le Gonidec Y.2, Gibert D.1, Voisset Michel3, Adamy J.4
Affiliation(s) 1 : CNRS, Inst Phys Globe Paris, CNRS, UMR 7154, F-75252 Paris, France
2 : Univ Rennes 1, Geosci Rennes CNRS UMR 6118, F-35042 Rennes, France
3 : IFREMER, Departement Geosciences marines, France
4 : TOTAL, France
Source Geophysical Journal International (0956-540X) (Wiley-blackwell Publishing, Inc), 2010-09 , Vol. 182 , N. 3 , P. 1524-1542
DOI 10.1111/j.1365-246X.2010.04700.x
WOS© Times Cited 23
Keyword(s) Controlled source seismology, Seismic tomography, Acoustic properties, Submarine landslides, Atlantic Ocean
Abstract 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 acquisition geometry. This innovative experiment combined with advanced processing succeeded in reaching lateral and vertical resolution (2.5 and 1 m) in accordance with the objectives of imaging fine scale structures and correlation with in situ measurements. To illustrate the technological and processing advances of the approach, we present a first application performed during the ERIG3D cruise offshore Nigeria with the seismic data acquired over NG1, a buried Mass Transport Complex (MTC) interpreted as a debris flow by conventional data. Evidence for a slide nature of a part of the MTC was provided by the high resolution of the OBH depth images. Rigid behaviour may be inferred from movement of coherent material inside the MTC and thrust structures at the base of the MTC. Furthermore, a silt layer that was disrupted during emplacement but has maintained its stratigraphic position supports a short transport distance.
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Ker Stephan, Marsset Bruno, Garziglia Sebastien, Le Gonidec Y., Gibert D., Voisset Michel, Adamy J. (2010). High-resolution seismic imaging in deep sea from a joint deep-towed/OBH reflection experiment: application to a Mass Transport Complex offshore Nigeria. Geophysical Journal International, 182(3), 1524-1542. Publisher's official version : https://doi.org/10.1111/j.1365-246X.2010.04700.x , Open Access version : https://archimer.ifremer.fr/doc/00044/15510/