Japan Geoscience Union Meeting 2015

Presentation information


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

[M-IS25] tsunami deposit

Sun. May 24, 2015 9:00 AM - 10:45 AM 201B (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), Chair:Kazuhisa Goto(International Research Institute of Disaster Science (IRIDeS),Tohoku University), Yasuhiro Takashimizu(Mathematical and Natural Sciences, Institute of Humanities, Social Sciences and Education, Niigata University)

10:30 AM - 10:45 AM

[MIS25-07] Was the 2011 Tohoku tsunami once-a-millennium disaster in the Sendai Plain?

*Yuki SAWAI1, Yuichi NAMEGAYA1, Toru TAMURA1, Rei NAKASHIMA1, Koichiro TANIGAWA1 (1.National Institute of Advanced Industrial Science and Technology (AIST))

Keywords:Japan Trench, Tsunami deposit, Recurrence interval

Geological evidences show that recurrence intervals of outsize tsunamis along the Japan Trench may be shorter than previously thought. In the Sendai Plain, A sand layer was found in peat above a historical volcanic ash (AD 915), and is dominated by brackish-marine diatoms. Radiocarbon dating obtained from plant macrofossils permits correlation of the sand layer for the 1454 Kyotoku tsunami. The distribution of the layer shows that the run-up distance of the 1454 tsunami was at least 1 km, longer than any tsunamis that occurred during the last 200 years except for the 2011 Tohoku tsunami. Numerical simulation for tsunami inundation suggests that such an inundation distance is accounted for a rupture similar to that of the Jogan earthquake. The 1454 Kyotoku tsunami is thus considered as an unusually large tsunami comparable with the AD 869 Jogan and 2014 Tohoku tsunamis, indicating that such tsunami inundated on the Sendai Plain more often than previously thought.