Weak-anisotropy approximations of P-wave phase and ray velocities for anisotropy of arbitrary symmetry

0458982 - GFÚ 2017 RIV CZ eng J - Článek v odborném periodiku
Farra, V. - Pšenčík, Ivan
Weak-anisotropy approximations of P-wave phase and ray velocities for anisotropy of arbitrary symmetry.
Studia geophysica et geodaetica. Roč. 60, č. 3 (2016), s. 403-418. ISSN 0039-3169. E-ISSN 1573-1626
Institucionální podpora: RVO:67985530
Klíčová slova: weak anisotropy * P-wave * phase velocity * ray velocity
Kód oboru RIV: DC - Seismologie, vulkanologie a struktura Země
Impakt faktor: 0.764, rok: 2016

We test the accuracy of the previously derived weak-anisotropy approximations of the P-wave phase and ray (group) velocities. The formulae are of varying accuracy, and are applicable to weak or moderate anisotropy of arbitrary symmetry and orientation. They have a form of expressions for squares of phase velocity depending on the phase-velocity direction and of ray velocity depending on the ray-velocity direction. Both velocities are expressed in terms of three elements of the rotated Christoffel matrix, which depend linearly on the parameters specifying the medium, the weak-anisotropy parameters. The least accurate formulae are fully independent of the choice of a reference isotropic medium and depend linearly on weak-anisotropy parameters. The most accurate formulae depend only slightly on the ratio of S- and P-wave velocities of a reference medium, their dependence on weak-anisotropy parameters being quadratic. We show that the accuracy of the formulae is quite high, in fact, in some cases, it is close to the accuracy of the socalled anelliptic approximations, very accurate approximations based on a perturbation of the elliptical anisotropy.
Trvalý link: http://hdl.handle.net/11104/0259180