In order to extend seismic processing techniques to anisotropic media, it is essential that we have a measure of the different anisotropy parameters. The purpose of this study is to estimate Thomsen's parameters for P-wave, namely ε and δ for transversely isotropic (TI) media and also to extend to orthorhombic media by using the shifted hyperbola NMO equation. In order to estimate these parameters an estimate of vertical velocity is usually needed. We propose a method for estimating the anisotropy parameters independent of the vertical velocity; in fact we also estimate vertical velocity. This method was tested on the data collected over a synthetic model with both vertical transverse isotropy (VTI) and orthorhombic symmetries. This method fails when ε = δ , i.e. if the symmetry of the medium is elliptical.
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