Mapping the Pacific Slab Edge and Toroidal Mantle Flow Beneath Kamchatka

To clarify the upper mantle structure and dynamics of Kamchatka subduction zone, we conduct Rayleigh-wave phase-velocity azimuthal anisotropy tomography beneath using amplitude phase data teleseismic fundamental mode Rayleigh-waves at periods 25–150 s. With obtained anisotropic model, a 3-D shear-wave velocity (Vs) model is determined down to ?300 km depth. Beneath Kamchatka, subducting Pacific slab clearly imaged as dipping high-Vs zone on south Shiveluch volcano ?57°N latitude, whereas this absent north volcano, suggesting that edge exists in region. Visible low-Vs anomalies are revealed around edge. The generally exhibits fast-velocity direction (FVD) ?NE-SW area ?54°N dominant FVD rotates ?N-S or ?NNW-SSE ?54°–57°N latitude. FVDs parallel trench, which may result from shape-preferred orientation stratified oceanic lithosphere. At shallow depths (<?150 km), wedge ? NW-SE FVDs, E-W appear edge, form semi-toroidal reflect combination corner flow toroidal deform heat even melt near its