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).