Determination of the Seismic Velocity Structure of Sediments Using Both Sources and Receiver Near the Ocean Floor

摘要

A trial experiment proves the power and practicality of using both sources and receivers near the ocean floor to make precise measurements of deep (approx. 600 m) ocean sediment velocity structure. A digitally recording ocean bottom hydrophone receiver operating at a sampling rate of 1800 hz recorded clear arrivals with bubble pulse frequencies of approx. 500 Hz from 4 lb. explosive charges detonated at depths of 5500 m along a km long wide angle reflection profile. It is shown that corrections for changes in source depth may be computed without approximation and without prior knowledge of the velocity structure. The experiment was located at longitude 56 W in the trough of the Kane Fracture Zone. The velocity structure of the 1 km thick sedimentary section reveals a 310 m thickness of 3 km/s material overlying igneous basement. (Author)