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.
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.
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.