This research will map the orientation and extent of anisotropy in both the suboceanic and subcontinental upper mantle. The analysis will be done by means of differences between azimuthal velocity variations of the two quasi-shear phases produced by shear wave incidence on an anisotropic medium. The primary dataset will be intermediate-period and broadband records from global digital catalogs and digitized long-period records from the WWSSN. Preliminary analysis of S and SS phases that traverse the North Atlantic shows potential examples of shear-wave splitting that support the presence of upper mantle anisotropy.
