Geoacoustic characterisation of fine-grained sediments using single and multiple reflection data

Fine-grained sediments commonly occur in areas of the continental shelf where wave and current energy are weak. Bulk density, compressional wave speed and attenuation are fundamental physical properties of these sediments required for predicting the response of the seabed for diverse branches of marine science. The traditional coring approach is time and labor-intensive, with large uncertainties associated with sediment disturbance in the sampling phase. Acoustic methods offer the advantages of remote sensing, i.e., sampling the sediment structure without mechanical disturbance and a significantly larger seabed coverage rate per unit time. Two different acoustic methods are described: one using short-range single-bounce interactions with the seabed, and the second using long-range modal propagation to infer the sediment properties. The relative strengths and sensitivities of each approach are explored through simulations guided by experience with measured data.