Inversion of P-wave velocity anisotropy

Summary. We examine the way in which measurements of velocity anisotropy can add to our understanding of upper mantle structure. Measurements of P -wave velocity anisotropy in a single plane contain very little direct information about the anisotropic structure. A promising technique is to fit the observed velocity variation with a mixture of an assumed anisotropic constituent and a proportion of isotropic material. Using this technique, mixtures of orthorhombic and transversely isotropic olivine are obtained, which are in excellent agreement with observed velocity variations in the Pacific.