A fault-zone conductor beneath a compressional inversion zone, northeastern Honshu, Japan

A resistivity section based on magnetotelluric data was obtained for the Shonai Plain fault in northeastern Honshu, Japan. Faults in this area were created as normal faults during the opening of the Japan Sea in the Miocene but are now reactivated as high‐angle reverse faults under compressional tec...

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Bibliographic Details
Published in:Geophysical research letters 2011-05, Vol.38 (9), p.np-n/a
Main Authors: Ichihara, Hiroshi, Uyeshima, Makoto, Sakanaka, Shinya, Ogawa, Tsutomu, Mishina, Masaaki, Ogawa, Yasuo, Nishitani, Tadashi, Yamaya, Yusuke, Watanabe, Atsushi, Morita, Yuichi, Yoshimura, Ryokei, Usui, Yoshiya
Format: Article
Language:English
Subjects:
Activation
Earth sciences
Earth, ocean, space
Electrical resistivity
Exact sciences and technology
fault reactivation
fault zone conductor
fault-valve behavior
Faults
Fluid dynamics
Fluid flow
Fluids
Fracture mechanics
Geological faults
inversion tectonics
magnetotelluric
resistivity structure
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Summary:A resistivity section based on magnetotelluric data was obtained for the Shonai Plain fault in northeastern Honshu, Japan. Faults in this area were created as normal faults during the opening of the Japan Sea in the Miocene but are now reactivated as high‐angle reverse faults under compressional tectonics. Geological interpretations of the resistivity section support the proposed fault reactivation. An estimated east‐dipping conductor along a deep part of the Shonai Plain fault system probably represents a fluid‐rich zone around the fault zone. The high 3He/4He ratio near the fault indicates transportation of mantle fluid through this fluid‐rich zone. These evidences may reflect the development of pronounced fracture permeability after fault rupturing, as in the fault‐valve hypothesis. Key Points An obvious low‐resistivity zone along a reactivated fault was imaged Interconnected fluid from mantle and high fracture permeability were indicated Fault reactivation was also indicated based on a MT survey
ISSN:0094-8276
1944-8007
DOI:10.1029/2011GL047382