Measuring Shallow Sediment Velocity Structure with CDP Gathers and Sonobuoy Profiles

摘要

As part of USNS Bowditch Cruise 621098, a high resolution MCS reflection survey of the Persian Gulf, 48 NAVO-supplied sonobuoys were deployed and recorded. 32 of these returned useful data, the analysis if which is presented here. The principal purpose of this study was to determine detailed shallow velocity structure which would complement those obtained as part of the MCS processing and analysis. Two analysis methods were employed: interactive ray tracing and determination of the angle of critical reflection from the seafloor. This latter method can tell us the velocity of sediment on the seafloor, which cannot be determined using 'normal' means. Ray tracing returned velocity functions extending as deep as 2 km in some cases. An important result is that in an area of the central gulf, there exists a thin, high velocity layer not far below the seafloor. It is difficult to measure the thickness of this layer, but its velocity and depth are well constrained.