2019 Volume 2019 Issue 51 Pages 53-59
Re-examination of paleo-tsunami deposit ages was conducted to contribute establishment of paleo-tsunami scenarios and risk assessment along the Pacific coast of Tohoku region. Fifteen new radiocarbon dates were obtained from handy-Geoslicer samples drilled at Onuma, Minami-Sanriku Town Miyagi Prefecture. These new dates consistent to stratigraphy and tephras enabled us to establish an age model and to estimate ages of paleo-tsunami deposits. Ages of six paleo-tsunami deposits were estimated: S1 (680-1010 cal BP), G1 (1540-2350 cal BP), G2 (2730-3630 cal BP), G3 (3850-4080 cal BP), S2 (4450-4780 cal BP), and S3 (5540-5730 cal BP). Moreover, there was no paleo-tsunami deposit correlated with the AD 869 Jogan tsunami, indicating the tsunami behavior differently to the 2011 Tohoku-oki tsunami. In the future, a tsunami deposit survey should be conducted on the southern part of the Sanriku Coast.
