We propose a kinematic inversion technique based on the first-order perturbation method for anisotropic media. In contrast to previous techniques, this one can be used to invert traveltimes of quasi-compressional as well as split quasi-shear waves, even if the initial unperturbed medium is isotropic. In principle, the technique is applicable to general 3-D laterally inhomogeneous anisotropic structures with an arbitrary degree of anisotropy. Here, however, for simplicity, media with hexagonal symmetry are considered. The effectiveness and limitations of the inversion technique are illustrated with synthetic VSP traveltime data. A simple linear variation of elastic parameters with depth is considered. The inversion scheme is tested both on data with pronounced shear wave splitting and data in which the shear wave splitting is negligible, the limiting case being data generated for a vertically inhomogeneous isotropic structure.
Hexagonally symmetric media, quasi-P- and quasi-S-waves, traveltime inversion.
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