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Detailed Reference Information |
Costa Pisani, P., Reshef, M. and Moore, G. (2005). Targeted 3-D prestack depth imaging at Legs 190-196 ODP drill sites (Nankai Trough, Japan). Geophysical Research Letters 32: doi: 10.1029/2005GL024191. issn: 0094-8276. |
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Target-oriented 3-D prestack depth migration (PSDM), tied to known depths of key reflections at three ODP drill sites in the Nankai Trough, provides an improved representation of the subsurface depths and P-wave velocities around the drill holes. The resulting velocity volume is representative of the in situ velocities and allows us to extend the 1-D logging and core velocity data from the drill sites to the entire seismic transect. The PSDM velocity gradients closely match those at the drill sites, although the absolute values of the velocity curves are somewhat different. The average PSDM vertical velocity gradient above the d¿collement decreases from 0.99 s-1 seaward of the trench axis to 0.87 s-1 landward in the proto-thrust and frontal thrust zone, with a velocity inversion of about 50--150 m/s at the d¿collement. Below the d¿collement, the vertical gradient in the underthrusting section decreases from 0.97 s-1 in the basin to 0.72 s-1 beneath the frontal thrust. The lateral velocity gradient in the underthrusting section between the basin and the deformation front is 0.02 s-1, corresponding to ~10% thinning in the direction of subduction. |
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Abstract |
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Keywords
Exploration Geophysics, Computational methods, seismic, Exploration Geophysics, Data processing, Exploration Geophysics, Seismic methods (3025, 7294), Marine Geology and Geophysics, Seafloor morphology, geology, and geophysics, Marine Geology and Geophysics, Subduction zone processes (1031, 3613, 8170, 8413) |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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