Ambiguity In Avo/Ava Analysis For Anisotropic Media

Inversion of reflection coefficients of P waves, Rpp, at an interface between an isotropic over a monoclinic<br>medium with vertical plane of symmetry can not recover all the elastic constants of the bottom medium.<br>Numerical experiments with multiple azimuths and large offsets synthetic data at pre-critical incidence show<br>that there is an orthorhombic medium that fits the Rpp coefficients in this case. As a practical consequence Rpp<br>inversion in fractured medium can hope only to recover fractures strike but no information about the fractures<br>dip. This results holds for high contrast and large aperture data well beyond the range of validity of linearized<br>approximations for Rpp.