Estimating Sediment Properties with Sub-Bottom Reflection Signals

An inversion method based on sub-bottom reflections was investigated using the Shallow Water 2006 (SW06) experimental data. Because the direct arrivals in the water were influenced strongly by water sound speed inhomogeneities, the first sea-bottom reflection was applied as the reference path to calculate the relative arrival time and amplitude of sub-bottom reflection. Firstly the sediment sound speed and thickness were estimated using different source depths and receiver depths. Then the sediment attenuation was estimated by assuming that it had linear frequency dependence. The estimated values of the sediment properties compared well with the core data, the chirp sonar data, and the matched field inversion results.