We propose an algorithm for evaluating weak anisotropy (WA) parameters from deviations of measured qP wave particle motions from the corresponding phase normal at individual receivers in a borehole in a multiple-source offset VSP measurement. The formulae are derived under the assumption of weak but arbitrary anisotropy and vertical inhomogeneity of the medium. The formulae represent, in several respects, generalization of an algorithm proposed by Gaiser (1990). In this contribution, only basic formulae are presented. Tests of the proposed algorithm with synthetic data are under preparation.
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