Shear‐wave splitting to test mantle deformation models around Hawaii

Abstract

Seismic anisotropy allows us to study mantle deformation, and it can thus help to constrain mantle flow in the vicinity of hotspots. Hypotheses for the cause of seismic anisotropy in this environment include the “parabolic asthenospheric flow” (PAF) model: radial flow from a mantle plume impinging on 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‐wave splitting observations from land and ocean stations around the Hawaiian Islands that can be explained by the parabolic flow model. The observations suggest asthenospheric anisotropy under the Hawaiian islands, which may be explained if dislocation‐creep persists to deeper depths there than in other regions, perhaps due to the higher temperatures near hotspots.