The purposes of this group is to try to clarify spatial and temporal distributions of crustal fluids and their roles on properties of intra-island deformation and fault strength from combinations of field observations, experiments on material properties, theories, and unified analyses. Results obtained by the project “Geofluids: Nature and dynamics of fluids in subduction zones” will be developed, the following researches will be performed. (1) Estimate of precise electrical resistivity and seismic velocity structures in plural sites. (2) Theoretical and experimental estimates of properties of solid-liquid composites on resistivity and seismic velocity.
(3) Estimate of conditions of the crust as solid-liquid composites, namely spatial distributions of rock properties and amounts and existence forms of crustal fluids by unified analyses of the above results. Parallel to (1)- (3), (4) Selections of fields where we can observe crustal fluids that go up selectively through fault gouge zones and reach the ground surface.
(5) Installation of the in-situ automatic and continuous ground water data analyzing system around active faults, measurements of temporal changes of chemical and isotope compositions, and estimates of temporal changes in spatial distributions of crustal fluids in fault zones. (6) Development of a method of estimates of stick conditions of faults and spatial and temporal changes of fault strength, and clarifying spatial distributions of deformation properties and their temporal changes by combining the results obtained by B01 and B02 groups.