MEASURED ANISOTROPY IN PIERRE SHALE*

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Abstract
The five elastic coefficients which characterize a transversely isotropic medium have been measured for the Pierre Shale. The first‐arrival times deduced from two closely spaced vertical seismic profiles provide values of magnitude and direction of the phase velocity at a given depth for different locations of the sources. From these velocities, we can estimate the five elastic coefficients by assuming that the P‐ and SV‐wave velocities have only a small dependence on the angle of propagation. On the other hand, it is shown that the accuracy in the difference between the directions of propagation and particle motion is not sufficient to determine the anisotropy.This work was industrially sponsored through the Integrated Geophysics Project.