The low and high frequency limits for anisotropic parameters in a layered medium

The aim of this work is to investigate the relationship between the layer-induced anisotropic parameters å and ä from two layer isotropic medium when calculated in the low frequency limit (by Backus averaging) and in the high frequency limit (from the PP ans SS traveltime parameters). It shown that the effective medium from both PP and SS traveltime parameters computed from a two layer isotropic medium is not exactly a VTI medium. Nevertheless, the approximate solution can be used. The comparison between the low frequency limit and both PP and SS high frequency limits is discussed on synthetic and real data examples.