Japan Geoscience Union Meeting 2014

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Symbol M (Multidisciplinary and Interdisciplinary) » M-AG Applied Geosciences

[M-AG39_1AM1] Special Project for Reducing Vulnerability for Urban Mega Earthquake Disasters

Thu. May 1, 2014 9:00 AM - 10:45 AM 502 (5F)

Convener:*Naoshi Hirata(Earthquake Research Institute, the University of Tokyo), Hiroshi Sato(Earthquake Prediction Research Center, Earthquake Research Institute, The University of Tokyo), Kenji Satake(Earthquake Research Institute, University of Tokyo), Hiroshi Tsuruoka(Earthquake Research Institute, Tokyo Univ.), Muneo Hori(Earthquake Research Institute, The University of Tokyo), Shin'ichi Sakai(Earthquake Research Institute, University of Tokyo), Chair:Takeo Ishibe(Earthquake Research Institute, Univ. of Tokyo), Akinori Hashima(Earthquake Research Institute, The University of Tokyo)

10:00 AM - 10:15 AM

[MAG39-05] Distribution and structures of blind thrust faults beneath the Tokyo metropolitan area

*Tatsuya ISHIYAMA1, Hiroshi SATO1, Naoko KATO1, Susumu ABE2, Hidehisa WATANABE3, Nobuhiko SHIGA3 (1.Earthquake Research Institute, University of Tokyo, 2.R&D Department, JGI, Inc, 3.Mitsui Mineral Development Engineering Co., Ltd.)

We show subsurface geometries of several active blind thrusts beneath this highly urbanized area, based on tectonic landforms, high-resolution seismic reflection data, gravity anomaly data, and Quaternary stratigraphy. Deep seismic reflection profiles corroborate the notion that steeply dipping blind thrusts are reactivated normal faults originally formed by middle Miocene extensional tectonics. Despite very slow (less than 0.1 mm/yr) late Quaternary slip rates, our work suggests the presence of previously unrecognized faults that pose more seismic hazards to Tokyo and outlying communities, and urges more intense efforts to shed more light on the recent slip rates, magnitude and recurrence of the past earthquakes on them.