J

Oceanic plate-subduction playing a part in the subduction inputs performs megathrust earthquakes, arc volcanoes, and global material circulation by transporting the surface materials into Earth's deep interior. Although we have ever been under the impression that a subducting oceanic plate is a retrospective one observed at present mid-ocean ridges and ophiolites, we obtained the new perspectives about subducting oceanic plate using shipboard geophysical observations, deep sea drillings at the plate-boundaries, constructing the Oceanfloor Network Systems at both Japan Trench and Nankai Trough, and samplings from petit-spot volcanoes and trench oceanward slope, all conducted since 2000s. The nature of the oceanic plate as a subduction zone input, which is a boundary condition for these various tectonic activities and evolution of the Earth, is determined through various processes including the plate formation at the mid-oceanic ridge, the plate evolution at the deep sea basin, and alteration due to plate-bending related faulting near the trench. We welcome contributions from a broad range of earth science (geophysics, geochemistry, geology, petrology, drilling science, and so on) discussing topics related to the nature of the subduction inputs and its spatial variations. This session is supported by the focus group of hard rock drilling science.