[S-CG62] Activation of long-term volcanic activity by mega-earthquake

[SCG62-09] Deep seismic structure beneath volcanic arcs

*Junichi Nakajima¹ (1.Department of Earth and Planetary Sciences, Tokyo Institute of Technology)

Keywords:volcano, Tohoku, upwelling flow

The subduction zone system on the Earth is over 40,000 km long. The active processes –brittle deformation, metamorphism, convection and volcanism– beneath volcanic arcs are all linked with slab-derived fluids. Here I review seismological observations in subduction zones and show that a low-velocity zone is observed in the mantle wedge beneath all volcanic arcs. Interestingly, geometries of the low-velocity zone, however, vary depending on the dip and age of the subducting slab. I also present deep crustal structure in NE Japan and discuss how the crustal structure changes along the volcanic front, providing a clue to understand deep origins of arc magmas and ongoing processes beneath volcanic arcs.