Shear Wave Conversion Due to Subbottom Facets

A hybrid propagation model for propagation in stratified media has recently been developed, which combines the boundary element method with the direct global matrix method. This model allows for simulation of scattering and reverberation from elastic facets in a stratified seismo-acoustic ocean environment. The Green’s functions used in the boundary elements method can be determined very efficiently by means of a modified SAFARI code. This allows for modelling of very general stratifications, including any combination of fluid, isotropic elastic and transversily isotropic elastic layers. The use of the boundary element propagation code also allows calculation of the whole spectrum of output features from the direct global matrix method. This enables interpretation of the results in terms of basic wave physics and the separation of the total and the scattered field. Since only the facet boundary needs to be discretized, the hybrid method is computationally efficient compared with other numerical methods solving the two-way wave equation (i.e. finite difference and finite element models).