Research Objective Toward understanding both variety and universality of plate dynamics in various spatial-temporal scales,this group strives to clarify structural factors constraining tectonic processes from the evolution of trench-arc-backarc systems to the generation of great subduction earthquakes.
Research Approach Integrated geophysical-geological studies for investigating plate dynamics, including active/passive seismic studies, swath-bathymetry mapping, magnetic/gravity profiling, geodetic observation, are the primary research approaches of this group. This group also performs comparative studies of trench-arc-backarc systems at the Circum-Pacific margin to understand the variety and universality of the dynamics in these plate convergent margins

Research Objective In order to understand the process of plate subduction, we will focus on mechanisms controlling the dynamics of earthquake preparation, rupture and recovery processes by means of field observations, experimental and theoretical studies on materials sciences.
Research Approach Subduction zones are often characterised by great earthquakes along the plate boundary. In the subduction process, many processes occur along with brittle failure and ductile flow of rocks, including compaction and dewatering of sediments, dehydration reactions of rock forming minerals, and water-rock interaction involving changes in pressure and temperature. In order to understand the precise dynamics of plate subduction, our research includes the three following themes: 1) Quantitative studies of structures of deep seated accretionary masses and physical properties of the rock, reaction processes of minerals, migration process of water. 2) Experimental and theoretical studies on mechano-chemical processes of plate-boundary rocks, failure - recovery process, and 3) Detail studies of ocean drilling cores logged by the newly - designed riser drilling vessel now underconstruction to reveal the material properties of the subduction boundary and seismogenic zone.

Research Objective To utilize results from research into subduction zone structure and deformation, failure, and flow mechanisms of subduction zone materials, in order to develop models for plate behavior which integrate tectonic phenomena having diverse time scales.
Research Approach Among the research conducted in this group are projects to study the evolution of island arc-ocean trench systems through the modeling of subduction zone thermal structure, the effect of accretionary prism fluid flow on frictional properties of the seismogenic plate boundary, the influence of plate boundary topography on stress accumulation there, and earthquake rupture processes using seismic and tsunami waveform analysis.
Also, new numerical simulation software is being developed for the large-scale computations that will be required for the construction of an integrated model of plate dynamics accounting for interactions among various tectonic phenomena having diverse time scales. This will enable the soon-to-be-completed Earth Simulator to be used for for plate tectonic simulations on a scale encompassing the entire Japanese Archipelago.
Through the modeling of plate tectonic processes described above, this group hopes to increase our knowledge of temperature and pressure conditions inside tectonic plates as well our understanding of the ineractions between them, so as to elucidate the essential physics of volcanic and earthquake activity which have a profound influence on human society, and so contribute to disaster mitigation efforts.
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