Abstract:Forward modeling with conventional finite difference (FD) method usually suffers from numerical instabilities due to abrupt changes of both strong anisotropy and symmetry axis tilt in titled transversely isotropic (TTI) acoustic media. We derive a set of four first-order velocity stress equations from the second-order TTI coupled equations of quasi-P wave (qP), and build a high order FD with perfectly matched layer (PML) absorbing boundary conditions in staggered grid. Furthermore, in order to improve stability about FD scheme in TTI media, we develop pseudo-spectral method, which realizes first-order qP wave equations with PML, guaranteeing a stable wave propagator. Finally, the proposed method provides stable and highly accurate TTI modeling results in 2D TTI wedge and BP model, even in models with strong anisotropy and sharp contrasts, which proves accuracy, validity and applicability of the proposed method.
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