Scattering of interface waves from pointlike obstacles

A method is presented for efficiently computing or estimating low-order elastic wave scattering, from a pointlike inhomogeneity in a bounded medium, into interface as well as bulk modes. The particular system considered is a half-space of fluid overlying a half-space of a linear elastic solid, with the obstacle placed in the solid very near the interface. Boundary constraints are enforced as an improvement to the bulk scattering vertex, so that the stratified-medium Green’s function is used to propagate scattered waves at each perturbative order. Analytic approximation of the first-order scattering amplitude, based on the symmetries of the scattering vertex and the interface-wave pole structure, makes it easy to identify the qualitatively different components of the scattered wave, and their dependence on medium properties.