Fig. 3. Phenomenological splitting parameters for SKS waves received at a hypothetical station. (Right) For an earth model with two 50 km thick hexagonally-anisotriopic layers overlying an isotropic halfspace. The symmetry axis is horizontal in both layers, an has an azimuth of N30E in the top layer and N60E in the bottom layer. (Left) For an earth model with one 100 km thick anisotriopic layer overlying an isotropic halfspace. The anisotropic tensor is the arithmetic mean of the tensors in the two-layer case. Splitting parameters are computed by the cross-correlation method from synthetic SKS phases. Note that the two layer case has the more complex pattern. (Postscript version)