Shear-wave splitting observations in the vicinity of subduction zones of the Pacific indicate that average olivine a-axis orientations beneath back-arcs are variable within and between subduction zones, and those beneath slabs in the seaward-side mantle are predominantly parallel to the trenches. The PI proposes to use a 3-D numerical model to study the effects of simultaneous down-dip and rollback motion of a non-planar plate, and the motion of an overriding plate on upper mantle flow and anisotropy in the vicinity of a subducting slab. The influence of simultaneous slab motion, plate geometry and overriding plate kinematics on mantle flow and anisotropy needs to be examined in more detail than has presently been done. The 3-D numerical model will produce results that can be compared to current shear-wave splitting observations.
