HR: 1340h
AN: T13C-1383    [Abstracts]
TI: Tsunami Events of the Nankai Earthquakes During the Last 4000 Years
AU: * Matsuoka, H
EM: matsuoka@cc.kochi-u.ac.jp
AF: Kochi University, akebono-cho 2-5-1, Kochi, 780-8520 Japan
AU: Okamura, M
EM: mako-ok@cc.kochi-u.ac.jp
AF: Kochi University, akebono-cho 2-5-1, Kochi, 780-8520 Japan
AU: Tsukuda, E
EM: e-tsukuda@aist.go.jp
AF: National Institute of Advanced Industrial Science and Technology, Chuou-7th, higashi1-1-1, Tsukuba, 305-8567 Japan
AB: The Nankai earthquakes are interplate earthquakes along the Nankai Trough and one of the most historically documented earthquakes in the world. Nine Nankai earthquakes have been identified from historical documents after the Hakuho-Nankai earthquake at A.D.687 (Usami, 1996; Tuji, 1999). The purpose of this study is to reveal pre-historical occurrences of the Nankai earthquakes by using geological evidence. A small pond named Tadasuga-ike located in the southern Shikoku Island is selected for this study. The last Nankai earthquake of 1946, Tadasuga-ike subsided coseismically and was covered by seawater of tsunami. We collected six 5m long sediment cores from the pond and identified fourteen layers of tsunami sediments. Radiocarbon datings indicated these layers deposited during the time period between 1300 yBP and 3800 yBP. These results suggest the recurrence intervals of the Nankai earthquakes are 200 years in average rate during the last 4000 years.
DE: 7221 Paleoseismology
DE: 7223 Seismic hazard assessment and prediction
DE: 4564 Tsunamis and storm surges
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting