Portions of the lowermost mantle nearly 3000 km beneath the Earth’s surface may have a preferred orientation (anisotropy). UTIG scientists Jay Pulliam and Mrinal Sen observed split shear waves, which are diagnostic of anisotropy along the waves’ path, arriving at UTIG’s Hockley Seismic Station from deep earthquakes in the southwest Pacific. These waves just grazed the core-mantle boundary beneath the central Pacific Ocean at the deepest extent of their travels. Sen and Pulliam developed and applied an innovative technique to produce a model of the lowermost mantle beneath the Central Pacific by matching the split waves with theoretical seismograms synthesized by a numerical technique called the reflectivity method. The modeling method holds the model’s upper layers fixed but adjusts the lowermost layers using a global optimization technique called Very Fast Simulated Annealing (VFSA) until they match the specific properties of the portion of the lowermost mantle sampled by the data. Pulliam and Sen’s modeling has shown that the mechanism producing anisotropy beneath the Central Pacific is different from the one at work beneath the Caribbean and Alaska, for which split shear waves have also been observed. This result has important implications for the style and geographical pattern of convective flow in the mantle. Since this flow is an important component of plate tectonics, the investigation of a remote region halfway to the center of the Earth is significant to those of us living on the Earth’s surface.