| Abstract: | Laboratory measurements, and a few in situ observations, show that saturated marine sediments have interdependent mechanical and acoustical properties, Acoustically, of particular importance are the acoustic impedance, velocity of sound and the sound attenuation coefficient of the sediment. The first two properties can be measured relatively easily from a surface ship; the measurement of attenuation however, is more problematical. It is suggested that this can be achieved by a quantitative treatment of the acoustic data collected during routine sub-bottom profiling over a variable thickness of superficial sediments. In the assessment of four different sediment locations in the Irish Sea it was found that quantitative treatment of the acoustic signals yielded both a value of the attenuation coefficient as well as a measure of the frequency dependence of the attenuation. In addition a statistical analysis of the signal intensities seems to provide an indication of the relative roughness of the bottom and sub-bottom interfaces. From the wide range of information provided the mechanical properties of the sea-floor sediment may be estimated. |
