Sediment contributions to group velocity in shallow water

Abstract

Dispersion curves are used to examine the effect of sediments on group velocity, and the problem further dissected by a direct look at the relative contributions of the sediment layers to the group velocity integral. The environments of interest have water depths less that 150 m and sediment thickness of the order of 50 m. The range of frequencies considered is between 25 and 600 Hz. A systematic variation of sediment types and velocity profiles will be examined to find features of the dispersion curves which might be used to extract information about the bottom from shot data. In the presence of stable water velocity profiles, gradients in the sound velocity in the sediment can be detected, as can layering, provided such layers are near the water-sediment interface. Highly variable water sound velocity profiles limit information available concerning the sediment to gross features such as sediment type. [Work supported by Naval Ocean Research and Development Activity.]