Abstract
Magnetotelluric transect across the Niigata-Kobe Tectonic Zone, central Japan: A clear correlation between strain accumulation and resistivity structure
DPRI, Kyoto University, Uji, Japan
DPRI, Kyoto University, Uji, Japan
ERI, University of Tokyo, Tokyo, Japan
Department of Earth Sciences, University of Toyama, Toyama, Japan
DPRI, Kyoto University, Uji, Japan
Department of Earth Sciences, University of Toyama, Toyama, Japan
Department of Civil Engineering, Tottori University, Tottori, Japan
ERI, University of Tokyo, Tokyo, Japan
VFRC, Tokyo Institute of Technology, Tokyo, Japan
Department of Earth Science and Technology, Akita University, Akita, Japan
Department of Earth Science and Technology, Akita University, Akita, Japan
RCPEVE, Tohoku University, Sendai, Japan
AIST, Tsukuba, Japan
JAMSTEC, Yokosuka, Japan
JAMSTEC, Yokosuka, Japan
Department of Earth and Planetary Sciences, Kobe University, Kobe, Japan
Department of Applied Science, Kochi University, Kochi, Japan
ISV, Hokkaido University, Sapporo, Japan
ISV, Hokkaido University, Sapporo, Japan
EPRC, Tokai University, Shizuoka, Japan
Department of Civil Engineering, Tottori University, Tottori, Japan
Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo, Japan
ERI, University of Tokyo, Tokyo, Japan
DPRI, Kyoto University, Uji, Japan
DPRI, Kyoto University, Uji, Japan
DPRI, Kyoto University, Uji, Japan
We obtained an electrical transect image of the Niigata-Kobe Tectonic Zone (NKTZ). Several major active faults are located in this zone of concentrated deformation. The main features of the final two-dimensional model are a thick resistive block in the upper crust, with a thinned-out portion beneath the Atotsugawa Fault, and a strong conductor in the lower crust that intrudes upward into the upper resistor. The upper crustal resistive zone corresponds well to the spatiality of the NKTZ, and relatively conductive zones sandwiching this resistor may contribute to observed changes in displacement rates. The overlapping locations of the conductor and the low-velocity body in the lower crust indicate that the conductor represents a zone that was weakened by fluids. Given that microearthquakes are localized in the regions between the resistive and conductive zones, we suggest that the distribution of earthquakes is influenced by intrusions of fluid derived from the conductor.
Received 16 July 2009; accepted 15 September 2009; published 23 October 2009.
Citation: (2009), Magnetotelluric transect across the Niigata-Kobe Tectonic Zone, central Japan: A clear correlation between strain accumulation and resistivity structure, Geophys. Res. Lett., 36, L20311, doi:10.1029/2009GL040016.
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