Improved Geometrical Spreading Approximation in Layered Transversely Isotropic Media

The geometrical spreading approximations for a layered medium were shown for isotropic case (Ursin, 1990) and transversely isotropic case (Ursin and Hokstad, 2003). We derive new approximation for the relative geometrical spreading in a layered transversely isotropic medium using three traveltime parameters, two-way vertical traveltime, the normal moveout velocity and the heterogeneity coefficient. Few numerical tests show that the new approximation is more accurate that the standard approximation (Ursin and Hokstad, 2003) using the traveltime approximations.