CAUSES AND REDUCTION OF NUMERICAL ARTIFACTS IN PSEUDOSPECTRAL WAVE-FIELD EXTRAPOLATION

Artefacts and local instabilities are common in numerical solutions of seismic wave equations. Although many of these are already known, mos t are not well documented in an accessible form. One form of artefacts is a consequence of partial derivative operators that are non-local a nd are associated with the interaction between the propagating wavefie ld and the medium at discontinuities in material properties. When pseu do-spectral solutions are used, heterogeneous wave equations may be ac curately solved in a wide dynamic range using even-based Fourier trans forms on a staggered grid. Regardless of the implementation of a spati al differentiator, use of homogeneous wave equations or of standard (n on-staggered) grids gives less accurate results. Synthetic examples in clude heterogeneous acoustic, elastic and poroelastic (Blot) equations .