Quasi-acoustic Approximations for qSV-waves in a Transversely Isotropic Medium

We derive "quasi-acoustic" approximations valid for qSV-wave propagation in transversely isotropic and tilted transversely isotropic media by applying approximation extracted from acoustic approximation for qP-wave propagation. One approximation has the same accuracy as qP-wave acoustic approximation for the same range of horizontal slowness, the other approximations are wide-angle approximations.