## Prevailing-frequency approximation of the coupling ray theory for S waves
along the SH and SV reference rays.

**Ludek Klimes** and
**Petr Bulant**
### Abstract

The coupling ray theory S-wave tensor Green function is frequency dependent.
Its prevailing-frequency approximation removes this frequency dependence and
allows us to introduce the coupling-ray-theory travel times and the
coupling-ray-theory amplitudes, and to process the coupling-ray-theory
wave field in the same way as the anisotropic-ray-theory wave field.
This simplification may be decisive when storing the tensor Green function
at the nodes of dense grids.

The coupling ray theory is usually applied to anisotropic common reference rays,
but it is more accurate if it is applied to reference rays which are closer
to the actual wave paths. In a generally anisotropic medium, the actual wave
paths may be approximated by the anisotropic-ray-theory rays if these rays behave
reasonably. In an approximately transversely isotropic medium, we can define and
trace the SH and SV reference rays, and use them as reference rays for the
prevailing-frequency approximation of the coupling ray theory.

We test the accuracy of the proposed prevailing-frequency approximation
of the coupling ray theory numerically. The additional inaccuracy introduced
by the prevailing-frequency approximation is smaller than the inaccuracy
of the standard frequency-domain coupling ray theory.

### Whole paper

The paper is available in
PDF (668 kB).

In: *Expanded Abstracts of 15th Int. Congress of the Brazilian
Geophysical Society (Rio de Janeiro 2017) (CD-ROM)*,
8332017013118262 (4 pp.), Brazilian Geophysical Society, ISSN 2175-4551.

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