This section uses
notation loosely by calling the fast wave modes P waves, but
just in the sense that they are primary waves, not that their
polarization aligns with the direction of propagation. This
terminology works fine for transverse isotropy where the fast wave
modes are always faster than the other two modes. For a general
anisotropic case we may not be able to call specific modes fast
or slow, since their velocity surfaces may cross.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.