Frequency domain 3D elastic wave propagation in general anisotropic media

Elastic wave propagation in 3 spatial dimensions is modeled using a wave equation containing the full stiffness tensor consisting of 21 independent components. This allows modeling in general anisotropic media. The wave equation is discretized on several Cartesian and rotated Cartesian staggered finite-difference grids (using a 2nd order approximation). The grids are linearly combined and, in combination with a antilumped mass strategy, minimize numerical dispersion while requiring a low number of grid points per wavelength. In case not all 21 components need to be modeled, an approximation of the stiffness tensor can be used (e.g., orthorhombic anisotropy, TTI, ...). This results in a linear system of equations, which is solved using an iterative method. The modeling of all 21 components of the stiffness tensor (or an approximation) enables the development of new waveform inversion functionalities.