Dynamic attenuation extraction of seafloor sediments from very high resolution acoustic data

Abstract

An approach to acquire geophysical information of seabed sediments as derrved from acoustic attenuation rs described. Using thefrequencies corresponding to the signal power spectrum maximum and a point 3 dB below, signal loss in the sediment is calculated. These results are compared to reference data for attenuatzon in sediments published by several authors. Data collected on the Grand Banks of Newfoundland during a controlled trawling experiment was processed using this technique, with results illustrating cbse agreement with the underpinning theory. Calculations offractal dimensions were performed to evaluate levels of roughness in the inner structure of the sediments. Since lower levels of the fractal dimensions represent less of a microfaunal presence [I] only the lower fractal valued data were used in the dynamic attenuation extractions. Hence, the correlations were found to be more rellable and reflectrve of homogeneous sediment structures.