MCS Data Analysis
Processing of the 3D MCS data set will begin onboard, starting with near-real-time stacking of the 2D lines as they are acquired. This will be accomplished using SioSeis, which has enabled near-real-time stacking of higher data volumes on numerous recent Ewing cruises. Initial stacking velocity functions will come from previous VSP and OBS results. Navigation data will be processed shipboard and ashore by Paul Henkart, who will produce a UKOOA navigation file, which will provide geometry information for 3D processing.
Processing of the 3D data will be conducted using 3D ProMax, which is running on a 4-CPU SGI Power Challenge at the University of Wyoming. Processing will include CMP sorting on 50 m cross-line bins, velocity analysis, NMO correction, stacking, and 3D migration. Data will be stored on a 10x9 Gb RAID disk drive system. Visualization of the 3D data volume will be conducted using Geoquest's IESX interactive 3D interpretation package and Geovision, a 3D structural visualization package. Both of these packages are available at UW.
Analysis and interpretation of the 3D data set will include both structural analysis, using 3D visualization tools, and quantitative analysis of seismic velocity, waveforms and reflection amplitudes across the region. We will produce maps of seismic velocity, fault density and orientation, estimates of the concentration and distribution of free gas, and a 3D stratigraphic framework. Velocity analysis will detect lateral changes in hydrate concentration on the scale predicted by Leg 164: VSP results showed changes of 100 m/s in the interval velocity of the 200-m-thick layer above the BSR, and similar changes in velocity beneath the BSR; these changes will be resolvable by the 4-km offsets of our data. Finally, the 4 km offsets will provide a rich data set for full waveform inversion of targets of interest, such as the BSR, the stringer, and sub-BSR reflectors, which will provide detailed P-velocities immediately around those targets. In sum, these results will enable us to image and interpret interrelationships among faulting, stratigraphy, sedimentation, and hydrate and gas occurrence.
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