Seismic Anisotropy and Intraslab Hydrated Faults Beneath the NE Japan Forearc

The water cycle in subduction zones is closely related to the generation of large earthquakes and arc magmas. Outer-rise hydrated faults subducting with oceanic lithosphere are suspected be important for cycle. However, geophysical evidence intraslab beneath forearc scarce. Here we present high-resolution P-wave anisotropic tomography Tohoku derived from arrival-time data recorded at both onshore offshore seismic stations. Trench-parallel fast velocity planes anisotropy revealed that intersect slab upper surface high angles (?45°–90°), reflecting aligned slab. Ruptures may cause earthquakes. hydrated-fault associated entering a near-trench asperity megathrust zone could have triggered great 2011 Tohoku-oki earthquake (Mw 9.0).