Spherical wave refraction with short distances of source from interface

If a source of seismic waves is situated a short distance from an interface there will be a considerable contribution to the field of the refracted wave from inhomogeneous waves excited by the source. This results information of a system of low-frequency nonuniformly refracted and outflowing waves, constituting the subject of this article. Investigation of the system of nonuniformly refracted and outflowing waves for a case when the source is in a high-velocity medium revealed that the polarization of nonuniformly refracted waves and the homogeneous components of the outflowing waves is close to linear. With increasing distance between the source and interface the amplitudes of these waves decrease rapidly. The authors give an in-depth analysis of the phenomenon for two cases: (1) plane interface of two fluid half-spaces, (2) plane interface of two elastic half-spaces. The article constitutes the first systematic analysis of the dynamic and kinematic characteristics of these types of waves. Comprehension of this phenomenon will prove useful in seismological and borehole investigations, particularly in seismic prospecting and especially when waveguides are present in the section.