*Nobuhiko Sugito1, Masao Iwai2, Hitomi Wakaki-Uchimura2, Hiroki Matsui2, Yasuhiro Suzuki3
(1.Faculty of Sustainability Studies, Hosei University, 2.Center for Advanced Marine Core Research, Kochi University, 3.Disaster Mitigation Research Center, Nagoya University)
Keywords:Submarine active fault, Multi-beam echo sounding, Piston coring, Foraminiferal assemblage, Fault-related landform, Nankai Trough
It is well known that there exist numerous submarine active faults in the Nankai Trough area. We have to reveal geometry and slip history of these faults, to reveal the origins of the past destructive earthquakes as well as to predict future large earthquakes in more detail. From this point of view, we have conducted a tectonic geomorphological and paleoseismological feasibility study on a submarine active fault of the Nankai Trough area in the Anoriguchi Canyon from FY2016 (Sugito et al., 2018). In this presentation, we report our result of a series of core analysis, including foraminiferal analysis and radiocarbon dating. Based on the data obtained, we infer that the submarine active fault across the Anoriguchi Canyon probably slipped one or more time(s) during this ~10,000 years to produce north-side-up vertical offset of ~10 m. This study illustrates the importance of the tectonic geomorphological and paleoseismological approaches in the studies of historical earthquakes and near-future earthquake potentials.
The drilled cores have been stored and analyzed under the cooperative research program of Center for Advanced Marine Core Research, Kochi University (16B070, 17A030, 17B030, 18A027, and 18B025). Takuya Matsuzaki and the colleagues (Kochi University) supported our research. Radiocarbon dating was conducted by Institute of Accelerator Analysis Ltd. We thank Hideaki Goto (Hiroshima University) for his constructive suggestion to this abstract. This study was supported by MEXT, under its Earthquake and Volcano Hazards Observation and Research Program, and JSPS KAKENHI Grant Number 15H02959.
Sugito et al., 2018, The 125th Ann. Meet. Geol. Soc. Japan, R8-P-7.