On Cagniard's problem for a qSH line source in transversely isotropic media

Lawrence H. T. Le


The paper studies the response to a qSH-pulse generated by a line source, of two homogeneous half-spaces (transversely isotropic elastic or viscoelastic) separated by a plane boundary.

For a simple model of two transversely isotropic half-spaces in welded contact, all the arrivals including the incident, reflected, head, transmitted and evanescent waves, that are predicted by the isotropic theory, are present. For the 15% change in wave speeds considered here, anisotropy changes the dynamic and kinematic characteristics of the pulses. Depending on the anisotropy factor, the change can be pronounced. Because of the significant time shift and amplitude variation of the first arrivals due to anisotropy, proper consideration of the anisotropy of the medium is necessary in interpreting vertical seismic profiles or crosshole seismic data by means of any travel time or amplitude tomographic scheme.

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