[S-SS31] Active faults and paleoseismology

[SSS31-22] Geological and geomorphological surveys, geophysical surveys, and borehole surveys along the Gomura and Yamada fault zone, and these applicabilities and efficiencies for development of the active fault evaluation

*Shinsuke Okada¹, Toshifumi Imaizumi², Atsumasa Okada³, Norihiro Nakamura², Tatsuro Fukuchi⁴, Kenshiro Otsuki⁵ (1.International Research Institute of Disaster Science, Tohoku University, 2.Graduate School of Science, Tohoku University, 3.Emeritus professor of Kyoto University, 4.Graduate School of Education & Human Sciences, University of Yamanashi, 5.Emeritus professor of Tohoku University)

Keywords:fault activity evaluation, geological and geomorphological survey, geophysical explorations, borehole surveys, Gomura fault zone, Yamada fault zone

In the case of lacking the overlying sediments and cross-cutting relationships between the sediments and active faults, the fault activities were not identified clearly. In such case, the methodology of fault activity evaluation is needed to be improved. In our project commissioned by Secretariat of Nuclear Regulation Authority (S/NRA/R), we execute geological and geomorphological survey, geophysical survey, and borehole surveys along the Gomura fault zone ruptured during the 1927 Kita-Tango Earthquake and the Yamada fault zone located in the south of Gomura fault zone. Base on these surveys and its analysis, we organized these surveying technique and its applied condition for the evaluation of active fault, then we aimed for an establishment of the methodology for synthetic evaluation approach of active faults.