Key points are not available for this paper at this time.
The theory, causes, observations, and possible applications of seismic anisotropy in the Earth have developed considerably since the last state of the art paper was published in 1977. The behaviour of waves in layered anisotropic media is now much better understood and the evidence for seismic anisotropy indicates that anisotropy is likely to be present throughout much of the crust and upper mantle.
Crampin et al. (1984) studied this question.