Modeling sideswipe in 2D oceanic seismic surveys from sonar data: Application to the Mariana arc |
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Authors: | Roland H. Gü nther, Simon L. Klemperer,Andrew M. Goodliffe, |
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Affiliation: | aDepartment of Geophysics, Stanford University, CA 94305-2215, United States;bDepartment of Geological Sciences, University of Alabama, Box 870338, Tuscaloosa, AL 35487, United States |
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Abstract: | In two-dimensional (2D) marine seismic-reflection surveys, out-of-plane rough seafloor bathymetry can cause multiple ocean-bottom reflections that complicate the interpretation of shallow reflections. Although migration corrects for the in-plane position of reflectors, it cannot resolve the inherent ambiguity in their out-of-plane positions. We show how swath bathymetry, routinely collected in many such surveys, can be used to model out-of-plane seafloor reflections and prevent their misinterpretation as subsurface geology. We use both raw and gridded multi-beam bathymetry data to build images that represent seafloor reflections in migrated seismic data. Comparison of these images to the seismic sections reveals whether suspicious features are out-of-plane water bottom reflections or subsurface reflections. Multi-channel seismic surveys across the Marianas intra-oceanic arc system provide examples where rough seafloor topography produced reflections that were initially misinterpreted. We use our seafloor reflection modeling (SRM) approach to help distinguish a possible landslide from a volcanic cone, to help distinguish real from apparent fault-plane reflections bounding a sediment-filled basin, and to verify that a possible magma chamber reflection results from sub-surface structure, not seafloor sideswipe. |
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Keywords: | Sideswipe Sonar Seismic reflection Mariana arc |
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