Shear-wave splitting to test mantle deformation models around Hawaii

Seismic anisotropy allows us to study mantle deformation, and it can thus h elp to constrain mantle flow in the vicinity of hotspots. Hypotheses for th e cause of seismic anisotropy in this environment include the "parabolic as thenospheric flow" (PAF) model: radial flow from a mantle plume impinging o n a moving lithosphere is dragged by the plate in the direction of absolute plate motion. In map view, this gives a parabolic pattern of flow, opening in the direction of plate motion. We present new shear-ware splitting obse rvations from land and ocean stations around the Hawaiian Islands that can be explained by the parabolic flow model. The observations suggest asthenos pheric anisotropy under the Hawaiian islands, which may be explained if dis location-creep persists to deeper depths there than in other regions, perha ps due to the higher temperatures near hotspots.