Multiple scattering of surface waves from discrete obstacles, Geophys

The surface wave T-matrix formulation which describes scattering from a discrete obstacle embedded in a stratified medium is extended to accommodate scattering from two or more obstacles. By exploiting the translation properties of the vector cylindrical wave functions and employing the definition of the surface wave T-matrix for a single obstacle it is possible to construct a composite T-matrix for a two-obstacle configuration in terms of the individual T-matrices. This procedure can be extended, recursively, to incorporate N obstacles. The scattered field contribu-tions from each obstacle including the entire hierarchy of multiple scattering interactions are clearly identifiable in the resulting expression. The formulation is applied to several two-obstacle configurations over a range of ku to investigate the implications of multiple scattering interactions for regional phases such as Lg propagating in the Earth’s crust and upper mantle. The results indicate that the significance of multiple scattering is dependent upon the size of the scatterers, their separation and orientation with respect to the incident wave. Multiple scattering is less pronounced for small scatterers (ku s 1.0) and is mos