Modeling of pseudo-acoustic P-waves in orthorhombic media with a lowrank approximation a

ABSTRACT Wavefield extrapolation in pseudo-acoustic orthorhombic anisotropic media suffers from wave-mode coupling and stability limitations in the parameter range. We use the dispersion relation for scalar wave propagation in pseudo-acoustic orthorhombic media to model acoustic wavefields. The wavenumber-domain application of the Laplacian operator allows us to propagate the P-waves exclusively, without imposing any conditions on the parameter range of stability. It also allows us to avoid dispersion artifacts commonly associated with evaluating the Laplacian operator in space domain using practical finite difference stencils. To handle the corresponding space-wavenumber mixed-domain operator, we apply the lowrank approximation approach. Considering the number of parameters necessary to describe orthorhombic anisotropy, the lowrank approach yields spacewavenumber decomposition of the extrapolator operator that is dependent on space location regardless of the parameters, a feature necessary for orthorhombic anisotropy. Numerical experiments show that the proposed wavefield extrapolator is accurate and practically free of dispersion. Furthermore, there is no coupling of qSv and qP waves, because we use the analytical dispersion solution corresponding to the P -wave