Open AccessNon‐geometrical waves–are there any? An asymptotic description of some ‘non‐geometrical’ phenomena in seismic wave propagation
Author(s) -
Babich Vasily M.,
Kiselev Aleksey P.
Publication year - 1989
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1989.tb01698.x
Subject(s) - rayleigh wave , wave propagation , seismic wave , love wave , physics , anisotropy , group velocity , geophysics , mechanics , classical mechanics , geology , longitudinal wave , mechanical wave , optics
Summary A review of a number of asymptotic studies of the so called ‘non‐geometrical’ phenomena in seismic wave propagation is presented. The results concerning high frequency asymptotics fall into two groups. Some phenomena are described by a slightly modified ray method or by considering higher order approximations. They are the much spoken of S*‐waves, the effect of wave tunnelling through a higher velocity layer and the low frequency depolarization of P‐, S‐, Love and Rayleigh waves described by the first‐order asymptotic approximation. Description of phenomena of the other group requires boundary layer techniques. These phenomena are: generation of S‐waves by a pressure centre due to velocity and density gradients or due to weak anisotropy as well as depolarization at caustics and in penumbra.