In situ properties of near-bottom sediments are determined using an experimental technique based on the dispersive properties of horizontally polarized surface waves generally known as Love waves. This technique basically consists of generating the Love waves, analyzing the recorded seismic signals to determine dispersion, and, finally, mathematically inverting the dispersion data to obtain a geoacoustic model of the sediment. In the field experiments, Love waves are generated using a torsional source and the generated signals are recorded with a linear array of gimbaled geophones that measure transverse horizontal motion. Experimental dispersion curves (wave velocity versus frequency), are then obtained from the recorded wavelets. These velocity waveforms are usually composed of overlapping modes and in order to reduce the influence of modal interference on the experimental phase velocity dispersion curves, a phase-matched filter is used to extract a smoothed phase velocity dispersion curve for the fundamental mode. The dispersion curve is then mathematically inverted to obtain a sediment model using a constrained least-squares method with singular-value decomposition and it is shown that the maximum parameter resolution depth can be estimated from the generalized inverse. Practical use of the technique is demonstrated by an analysis of the results of a field experiment carried out in a marine sand sediment. (C) 1995 Acoustical Society of America.
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