Japan Geoscience Union Meeting 2015

Presentation information


Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS25] tsunami deposit

Sun. May 24, 2015 6:15 PM - 7:30 PM Convention Hall (2F)

Convener:*Kazuhisa Goto(International Research Institute of Disaster Science (IRIDeS),Tohoku University), Masanobu Shishikura(Institute of Earthquake and Volcano Geology, National Institute of Advanced Industrial Science and Technology), Yuichi Nishimura(Graduate School of Science, Hokkaido University)

6:15 PM - 7:30 PM

[MIS25-P07] Nankai Earthquake events recorded in lacustrine sediment along the eastern coast of the Kii Peninsula, southwest Japan.

*Makoto OKAMURA1, Hiromi MATSUOKA1, Mitsuo TSUZUKI2, Kenji TORAYA2 (1.kochi University, 2.Disaster Mitigation Research Center, Nagoya University)

Keywords:Nankai Earthquakes, tsunami sediment

We research on tsunami sediment from lacustrine deposits along the Nankai Trough for prehistoric earthquake reconstruction. Total 21 cores are collected from the two lakes named Zasa-ike and Ashihama-ike, which locate behind coastal ridge along the southeastern coast off Kii Peninsula. Eighty C14 radioactive carbon dating are carried on plant remains containing the cores deposited under non-marine condition.
As a result, Ashihama-ike records two major events, 2000yBP to 2300yBP and 1000yBP to 1100yBP through 4500 years interval. The other Zasa-ike has six events are detected, which are 7000yBP, 6500yBP, 3500yBP, 2000-2300yBP, 1300yBP, and 1100yBP through the interval of 7500 years. The oldest event in these cores is conglomeratic coarse sediment covered by K-Ah tephra obtained from the lowermost part of cores. Both two events, 2000yBP to 2300yBP and 1000yBP to 1100yBP can be correlated among the ponds Ashihama-ike and Zasa-ike which has two kilometers in distance each other.