| Popis: |
Dispersion analysis of interface waves (Scholte/Stoneley/Rayleigh) has been used extensively to determine geoacoustic models of near‐bottom ocean sediments. In the traditional approach, a single seismic trace is analyzed to obtain group velocity dispersion using the multiple filter technique. A dispersion curve obtained in this manner reflects the averaged influence of the sediment acoustic properties over the entire path from source to receiver. Thus a geoacoustic model derived from this dispersion curve is not a true vertical section in the vicinity of the receiver unless the sediment properties do not change over the entire propagation path. However, when a linear array of receivers is used to obtain data simultaneously at a number of different ranges, it is possible to derive both group and phase velocity dispersion curves that correspond to propagation over a short portion (typically 5 m) of the total path at many different ranges. With this kind of data, the range‐dependent variation of geoacoustic properties in the sediment may be assessed. Results are presented based on data obtained with a 24‐receiver array and an explosive source, both deployed on the seafloor. Analysis of data from a number of shallow water sites suggests that there is a considerable amount of lateral inhomogeneity even over very short ranges. |
