The amplitude of a bottom simulating reflection (BSR), which occurs near the phase boundary between gas hydrate-bearing sediments and underlying gas-filled sediments, strongly depends on the frequency content of a seismic signal, as well as the impedance contrast across the phase boundary. Analysis indicates that seismic attenuation of gas hydrate-bearing sediments, velocity dispersion, and a transitional base all contribute to the frequency-dependent BSR amplitude variation in the frequency range 10–500 Hz. When velocity dispersion is incorporated into the BSR amplitude analysis, the frequency dependent BSR amplitude at Blake Ridge, offshore South Carolina, can be explained with gas hydrate-bearing sediments having a quality factor of about 250 and a transitional base with a thickness of about 1 meter.

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Posted August 2007

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