Abstract:

Because of the current interest in shallow water, propagation model capabilities have been developed for elastic, poro-elastic, and poro-acoustic sediments. These models incorporate depth and range heterogeneities in the sediments, which are assumed to be spatially isotropic. However, many shallow environments have a layered structure which often is more appropriately characterized as transversely isotropic. This feature arises from deposition and layering processes influenced by gravity, for example. Transversely isotropic sediments have elastic properties with considerable variations perpendicular to their natural plane, in which relatively little variation occurs. Efficient and accurate two-dimensional PE models are available for a variety of spatially isotropic sediments, and generalizations are needed for transversely isotropic cases. Our initial two-dimensional development assumes that the plane of the sediment is approximately horizontal. The PE formulation is presented for an elastic sediment and then extended to poro-elastic cases. An initial high-order implementation will be described. [Work supported by ONR.]