A Stable TTI Reverse Time Migration

We propose a stable TTI acoustic wave equation system by revisiting the anisotropic elastic equations. Based on a VTI system of equations which is equivalent to its elastic counterpart, we introduce self-adjoint differential operators in rotated coordinates to stabilize the TTI acoustic wave equations. Compared with conventional formulations, the new equation system does not add numerical complexity and can be solved by an extremely high order central finite-difference scheme. We show examples that our method provides stable and high quality TTI reverse time migration images.