DISCUSSION

The results obtained here and in particular (arearranged) and (Pwavep) show in general terms that the P-wave anisotropy parameter is smallest when the variation in the layer $\lambda$ Lamé parameter is large, independent of the variation in the shear modulus $\mu$. This result is therefore important for applications to porous layers containing pore fluids for which Gassmann's (1951) equation shows that the effects of fluids influence only the $\lambda$ Lamé constants, not $\mu$.Thus, the P-wave anisotropy parameter may be a useful hydrocarbon indicator in some situations. This result cannot, however, be considered in isolation, as there may be other effects that produce small P-wave anisotropies, and these should be explored and enumerated before any definitive statement can be made.