Lecture 4: S-waves
Of course, most of us, most of the time, are not concerned with shear waves. There is a good reason for this: they are more complicated, hence we have to work harder to get useful information out of them. Also, they attenuate more rapidly than P-waves do, so they penetrate the earth less deeply, and, below a thousand feet or so, they provide poorer resolution.
Figures & Tables
The subject of seismic anisotropy has a long history, but only recently has it come to be seen as a central feature of geophysics, as applied to the exploration for hydrocarbons and to their exploitation. The reason for the long neglect of anisotropy is, of course, that isotropy is simpler. The equations are simpler, and the application of one's intuition is more direct. And, perhaps because of their simplicity, these basic, isotropic ideas have enabled the discovery most of the world's known hydrocarbons.