First results obtained with the zero-order approximation of the quasi-isotropic (QI) approach are presented. The results were obtained with the updated version of the program package ANRAY. The QI results are compared with results obtained by the ray method for inhomogeneous anisotropic media and isotropic media. The results confirm theoretical conclusions that the QI approach represents a link between both ray methods. Presented numerical experiments show that the QI approach can be used in regions with extremaly weak anisotropy including isotropy, in regions in which the two qS waves couple and propagate together as well as in regions, in which the qS waves become decoupled and can thus be, in principle, studied by the ray method for anisotropic media. This is a good news for future applications of the QI approach, in which the QI approach should be combined with the ray methods for isotropic and anisotropic media.
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