Combination of a virtual wave and the reciprocity theorem to analyse surface wave generation on a transversely isotropic solid

At some distance from a high-rate source in an elastic half-space, the dominant wave motion at the free surface is a Rayleigh surface wave. The calculation of surface waves generated by a concentrated force in a half-space is a basic problem in elastodynamics. By straightforward manipulations, the result can be used to obtain surface waves for other kinds of wave-generating body-force arrangements. For example, appropriate combinations of double-forces (or dipoles) can be used to represent the surface loading due to laser irradiation, or due to acoustic emission from the opening of a sub-surface crack or from sliding over a fault surface. The surface wave motion is usually obtained by the application of integral transform techniques and the subsequent extraction of the surface waves as the contributions from poles in the integral for the inverse transform. In this paper, we use a much simpler approach based on the elastodynamic reciprocity theorem. We consider a transversely isotropic solid whose axis of symmetry is normal to the surface of the half-space. Surface wave pulses generated by a single force, by irradiation from a laser source, and by opening of a crack, have been determined.