Travel time tomography in anisotropic media

A useful method of estimating the velocities of geological structures between boreholes is traveltime tomography. Measurements of the traveltimes along different paths can be used to form an image of the velocity distribution. This approach is valid when seismic velocities are the same regardless of the direction in which waves propagate. Thus, the target media is required to be isotropic for the method to work correctly. However, in many environments, velocities to depend on the direction of wavepropagation. This effect, known as seismic anisotropy, can lead to distortions in tomographic images. The distortions may be serious enough to cause the images to be misinterpreted.