[S-SS13] Active faults and paleoseismology

[SSS13-P09] Deep seismic reflection profiling across the central portion of the Morimoto-Togashi fault zone, central Japan

*Tatsuya Ishiyama¹, Hiroshi Sato^1,5, Yoshihiro Hiramatsu², Tomotaka Iwata³, Hideo Saito⁴, Hirokazu Ishige⁴, Susumu Abe⁴ (1.Earthquake Research Institute, University of Tokyo, 2.School of Geosciences and Civil Engineering, College of Science and Engineering, Kanazawa University, 3.Disaster Prevention Research Institute, Kyoto University, 4.JGI, Inc., 5.Center for Integrated Research and Education of Natural Hazards, Shizuoka University )

Keywords:Active fault, Deep seismic experiment, Morimoto-Togashi Fault Zone

To define subsurface fault geometry, structural characters of fault-related folds and their structural growth during Quaternary, we collected ca. 24 km long, onshore multi-channel deep seismic reflection data across the central portion of the Morimoto-Togashi Fault Zone (MTFZ), an active reverse fault system located in the southwest extension of the Toyama trough, by using four Enviro-vib trucks as seismic sources and more than 970 seismic channels. Seismic reflection processing reveals the detailed subsurface structure in accordance with P-wave velocity structures obtained by refraction tomography. The depth-converted section that was correlated with the local Neogene strata successfully shows a moderately east-dipping reverse fault plane that is overlain by a monocline of Miocene to Pleistocene sedimentary units. We will also briefly explore structural relationships of folded middle-late Pleistocene fluvial terraces along the MTFZ and the fault trajectories and the growth of the fault-related folds.

Acknowledgements: This work was supported by MEXT “Comprehensive Research Project for the Morimoto-Togashi Fault Zone”.