Velocity structure of the methane hydrate formation at the Blake Outer Ridge
نویسنده
چکیده
Seismic analysis of data from the Blake Outer Ridge indicates the presence of hydratebearing sediments overlaying gas-saturated sediments in this region. In an attempt to determine possible lateral and vertical variations of the hydrate and gas sediments, I performed a 2-D velocity analysis along two approximately perpendicular seismic lines. Subsequent determination of the seafloor and BSR reflection coefficients along one of the lines resulted in additional zero offset P-wave velocity and density constraints. Combining these with the average interval velocity model of this line, I performed a 1-D elastic amplitude modeling of zero offset reflections using the Thompson-Haskell reflectivity method. The results suggest that regions showing a continuous bottom simulating reflection are characterized by a thick hydrate layer that has an average velocity of 2.1 km/s overlaying low-velocity (≈ 1.6 km/s) sediments of considerable thickness. This result agrees well with results discussed in SEP80. In regions of discontinuous BSR, a less pronounced velocity contrast is visible, probably indicating a decrease in the hydrate concentration of the sediments.
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