Ray synthetic seismograms for a 3-D anisotropic lithospheric structure, Phys. Earth. planet

The ray method is a useful tool for investigating the effects of anisotropy and inhomogeneity on the propagation of high-frequency seismic wave fields in elastic media. A program, based on the ray method, has been written to compute synthetic seismograms for 3-D laterally inhomogeneous media composed of isotropic and anisotropic inhomogeneous layers. General anisotropy, which can be described by 21 independent elastic parameters, may be considered by this program. Ray paths and travel times are evaluated by numerically integrating the corresponding ray tracing equations. When computing amplitudes, an approximate value of the geometrical spreading is obtained by numerically calculating the cross-sectional area of a ray tube. A paraxial ray approximation is used to evaluate the computed wave field in the vicinity of termination points of the rays. If a sufficiently dense system of ray-termination points covers a region on the surface of the model, synthetic seismograms along an arbitrary profile, fan or array in that region can be computed. In this paper, the effects of anisotropy on the propagation of elastic waves in a structure which simulates a continental subcrustal lithosphere are studied and P- and S-wave synthetic record sections along several profiles and fans are presented and discussed. 1