## Effects of attenuation, velocity and density
on SH-wave reflection/transmission coefficients
in isotropic, weakly attenuating media

**Milosz Wcislo**
### Summary

Study of the SH-wave reflection and transmission coefficients
in attenuative media using perturbation approach (Weak Attenuation
Concept - WAC) is conducted. It shows that differences in respect
to the elastic reference have greatest magnitude for angles close
to the critical incidence in the reference elastic medium. In this
region, value of the modulus of the coefficient is reduced.
For majority of models, these regions cannot be studied with
the use of WAC only inside narrow interval close the critical angle
(± 2 degrees), where the results are influenced by singularity of
the WAC formulas. Smaller deviations are encountered in the vicinity
of the Brewster angle, where in anelastic case reflection coefficient
is not equal to zero. Effects of changes of attenuation, density
and velocity of the medium on calculated coefficients are studied.
Tests indicate that contrast in quality factors between layers contributes
most to the differences in respect to elastic reference. Furthermore,
changes in velocity have particularly interesting results. With higher
contrast in velocities between layers, the difference at the Brewster angle
is increasing, but in the vicinity of critical angle is decreasing.
Investigation of effects of inhomogeneity of the slowness vector of
the incident wave and tests of accuracy of the approximation are included
in the study.

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*Seismic Waves in Complex 3-D Structures*, **28** (2018), 135-168
(ISSN 2336-3827, online at http://sw3d.cz).