9404875 Grand This research is a continuation of efforts to map the three- dimensional shear wave structure of the earth's mantle. Previously, the travel times of S, ScS and multiple bounce S phases have been measured and inverted to obtain a 3-D model of mantle structure beneath the Americas. New data will be collected from different types of seismic phases, SKS, SKKS, and multiple S, and from new station-earthquake combinations to increase the resolution and range of the previous results. New areas of study will include the upper mantle of Asia, Africa, and the northern Indian ocean. The results will provide resolution of mantle anomalies and questions such as the ultimate fate of subducting slabs, the origin of hotspots, and nature of mantle convection. ***
