Diffraction of Seismic Waves by an Irregular Edge of the Interface of Arbitrary Elastic Media

An asymptotic solution is given for the three-dimensional problem of seismic wave diffraction by a broken edge of the interface of heterogeneous elastic media of an arbitrary type of symmetry. The solution involves an approximation of the boundary layer by analogy with the scalar case. An approximated analytical formula, invariant for medium model and choice of coordinate system, has been obtained for amplitude of the wave dissipated with an edge breakpoint, to supplement and generalize the earlier results. Thus, the field of a dissipated wave is expressed by geometro-seismic field on the illuminated side of the shadow boundary through a definite special function of two variables, which is equivalent to earlier descriptions but is superior to them due to more convenient analytical properties. Arguments of this function, like the simplest cases, are expressed algebraically through differences of eikonal and/or curvatures of respective wave fronts. The obtained ratios are valid beyond acoustic regions. A numerical example is given of plane-wave diffraction on an absolutely absorbing rectangular-rimmed half-screen placed into a uniform two-axial crystal.