Wide-Angle Phase-Slowness Approximations in VTI Media

Several phase-shift migration methods depend on the vertical slowness, which in general can be represented as a nonlinear function of the horizontal slowness. In a VTI media, the dispersion relations relating the vertical and horizontal slowness, are complex expressions. Simple and accurate approximations of the exact slowness for both qP and qSV waves are desired for computationally fast and accurate migration algorithms. We describe new wide-angle phase slowness approximations for a VTI media.