## Perturbation of phase normal in weakly anisotropic media
- a preliminary study

**Ivan Psencik**
### Summary

The relation between phase normal and ray vector (unit vector in the
direction of energy flux) and the expression for the ray velocity
vector in an arbitrary weakly anisotropic medium is derived. The
relation allows unique determination of the ray vector for a given
phase normal and vice versa. In weakly anisotropic media, phase
normal and ray vector differ by a first-order quantity. This means
that in any expression containing a product of one of the mentioned
vectors with a first-order quantity, both vectors are interchangable.
The relation between phase normal and ray vector is linear.
Therefore, the relation cannot describe, in principle, triplication
of qS wavefront.

### Whole paper

The paper is available in
PostScript (115 kB)
and GZIPped PostScript (34 kB).

In: Seismic Waves in Complex 3-D Structures, Report 4, pp. 129-138,
Dep. Geophys., Charles Univ., Prague 1996.

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