P-SV REFLECTION MOVEOUTS FOR TRANSVERSELY ISOTROPIC MEDIA WITH A VERTICAL SYMMETRY AXIS

In a recently published short note, F.K. Levin (1989) discusses the relation between the "movement velocities' of P-P, P-SV, and SV-SV reflections from the bottom of a transversely isotropic layer with a vertical symmetry axis. We show that for Levin's cases the errors in SV velocity which he computes are quite predictable and can be reduced if one uses a simple approximate formula which includes the effect of polar anisotropy. Unfortunately, this formula does require at least an estimate of the anisotropy parameters. Second, the much smaller errors given by a more correct formula can be reduced further in most cases by computing moveout velocities with a range of X-distances slightly smaller than that used by Levin. Third, Levin's cases with very large errors are based on unusual elastic constants reported by Thomsen. -from Authors