The coupling ray theory is usually applied to anisotropic common rays, but it is more accurate if it is applied to reference rays which are closer to the actual S-wave paths. If we know that a medium is close to transversely isotropic, it may be advantageous to trace reference rays which resemble the SH-wave and SV-wave rays. This paper is devoted to defining and tracing these SH and SV reference rays in a heterogeneous generally anisotropic medium which is approximately transversely isotropic, and to the corresponding equations of geodesic deviation (dynamic ray tracing).
The improvement of the coupling-ray-theory seismograms calculated along the proposed SH and SV reference rays, compared to the coupling-ray-theory seismograms calculated along the anisotropic common reference rays, is numerically demonstrated in two approximately transversely isotropic velocity models.
Wave propagation, elastic anisotropy, heterogeneous media, S-wave coupling, transverse isotropy, symmetry axis, SH wave, SV wave, approximate transverse isotropy, reference symmetry axis, SH and SV reference rays.
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