Cruise Summary
09 April 2010 | Gulfport
Warren Wood
Blog
The purpose of this Naval Research Laboratory cruise was to measure the effects of geologic faulting on the acoustic wave propagation. We hypothesized that sound waves traveling across the faults or cracks in the earth tend to propagate slower, and with lower amplitude than waves traveling along the faults. To measure the amount of this effect, which is the sediment anisotropy, we used a special sound source and listened with vertical arrays of hydrophones. The special sound source, called DTAGS (Deep Towed Acoustics Geophysics System) is one that can produce low frequency sounds (220-1000Hz) in water thousands of meters deep. In addition to towing the sound source, it can also be placed on the seafloor directly, generating transverse, as well as the more common longitudinal waves. This experiment was conducted in an area where the water is about 800-900m deep, and the faults have been very extensively mapped. The area is part of a gas hydrate observatory run by the University of Mississippi at Oxford (Ole Miss).