Reasonable choices for material constants in seismic modeling

In exploration geophysics, the seismic response is often modeled with the assumption that the earth consists of homogeneous formations that may exhibit transverse isotropy and moderate, “constant Q” attenuation. The geophysicist usually has only incomplete knowledge of the formation characteristics and must make educated guesses at the unknown elastic and absorption parameters. An extension of the long‐wavelength‐equivalent‐medium theory to the anelastic case has been used to derive default options and stability criteria, which require minimal information from the geophysicist, appear reasonable for many earth materials and reduce to a proper description in the case of isotropy. A very simple earth model is used to demonstrate that parasitic modes are excited and the computations can become unstable when the assumed anelastic model parameters violate some stability condition or are inconsistent.