## Ray velocity and ray attenuation
in homogeneous anisotropic viscoelastic media

**Vaclav Vavrycuk**
### Summary

Asymptotic wave quantities such as ray velocity and ray
attenuation are calculated in anisotropic viscoelastic media
by using a stationary slowness vector. This vector generally is
complex valued and inhomogeneous, and it predicts the complex
energy velocity parallel to a ray. To compute the stationary
slowness vector, one must find two independent, real-valued
unit vectors that specify the directions of its real and
imaginary parts. The slowness-vector inhomogeneity affects
asymptotic wave quantities and complicates their computation.
The critical quantities are attenuation and quality factor
(Q-factor); these can vary significantly with the slowness-vector
inhomogeneity. If the inhomogeneity is neglected, the
attenuation and the Q-factor can be distorted distinctly by errors
commensurate to the strength of the velocity anisotropy
-- as much as tens of percent for sedimentary rocks. The distortion
applies to strongly as well as to weakly attenuative
media. On the contrary, the ray velocity, which defines the
wavefronts and physically corresponds to the energy velocity
of a high-frequency signal propagating along a ray, is almost
insensitive to the slowness-vector inhomogeneity. Hence,
wavefronts can be calculated in a simplified way except for
media with extremely strong anisotropy and attenuation.

### Whole paper

The reprint is available in
PDF (184 kB).

*Geophysics*, **72** (2007), D119-D127.

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