Weak-anisotropy approximation of P-wave reflection coefficient in anisotropic media of arbitrary symmetry and tilt

0556049 - GFÚ 2023 RIV US eng J - Journal Article
Pšenčík, Ivan - Farra, V.
Weak-anisotropy approximation of P-wave reflection coefficient in anisotropic media of arbitrary symmetry and tilt.
Geophysics. Roč. 87, č. 3 (2022), C39-C48. ISSN 0016-8033. E-ISSN 1942-2156
Institutional support: RVO:67985530
Keywords : P-wave transmission coefficients * arbitrary anisotropy * weak-anisotropy approximation
OECD category: Volcanology
Impact factor: 3.3, year: 2022
Method of publishing: Limited access
https://library.seg.org/doi/10.1190/geo2021-0471.1

Applicability of the approximate expression for the P-wave reflection coefficient at a weak-contrast reflector separating two weakly anisotropic half-spaces of arbitrary symmetry is extended to media of arbitrary symmetry and tilt. The reflection coefficient consists of the approximate PP reflection coefficient at a weak-contrast interface separating two reference isotropic half-spaces and a correction term due to anisotropy. Along an arbitrarily chosen profile, the 'isotropic term depends on the density and P- and S-wave contrasts, the correction term depends linearly on the contrasts of four profile weak-anisotropy (WA) parameters specifying anisotropy along the profile. In addition, both terms depend on the polar angle of incidence. In each half-space, the four profile WA parameters can be expressed as a linear combination of twelve of twenty one global WA parameters specifying anisotropy of the half-space. Coefficients of this linear combination are functions of the azimuth of the profile. WA parameters are a generalization of Thomsen parameters to arbitrary anisotropy, and represent an alternative to twenty one independent elements of the stiffness tensor. WA parameters can be used for the approximation of other related concepts as the reflection moveout or the geometrical spreading. Presented tests illustrate high accuracy and flexibility of the proposed formula for the P-wave reflection coefficient. They also show that very accurate results can be obtained for contrasts and anisotropy, which cannot be considered weak.
Permanent Link: http://hdl.handle.net/11104/0330426