Amplitude computation in heterogeneous media by ray perturbation theory: a finite element approach

The efficient determination of rays and paraxial rays is discussed for a heterogeneous isotropic medium. We propose a finite element approach in which the medium is divided into a set of elements with polynomial elastic parameter distributions. Using a perturbation approach, analytical expressions for rays, paraxial rays and traveltimes are obtained, as well as for the rotation angle of the shear wave polarization vectors. Extension of the method to media with hexagonal anisotropy is also shown. Examples of the calculation of rays, amplitudes and polarizations are presented.