Factoring anisotropy into iterative geometric reconstruction algorithms for seismic tomography

Tomography algorithms based on isotropic velocities need upgrading to perform well in anisotropic materials. In this paper, anisotropy is introduced in a SIRT-type algorithm in two ways. First the group velocity surfaces are assumed to be elliptical. Then the first order approximation of the velocity for transversely isotropic material is factored into the algorithm. It is shown that the latter modification which is less restrictive than elliptical anisotropy, can be conveniently inserted into existing algorithms while preserving their simplicity and calculation time. In addition to the mathematical formalism, applications with field data are discussed.

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