Paleo-tsunami history along the northern Japan Trench: evidence from Noda Village, northern Sanriku coast, Japan

Progress in Earth and Planetary Science

Masashi Watanabe¹  Yasutaka Iijima²  Taiga Inoue²  Yuichi Nishimura³  Kazuhisa Goto⁴  Daisuke Sugawara⁴ 

[1] Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku University;Department of Earth Sciences, Graduate School of Science, Tohoku University;Institute of Seismology and Volcanology, Faculty of Science, Hokkaido University;International Research Institute of Disaster Science, Tohoku University;

关键词: Paleo-tsunami;    Sanriku coast;    Japan;    Tsunami deposit identification;    AD 869 Jogan tsunami;    Storm wave;   

DOI  :  10.1186/s40645-017-0158-1

来源: DOAJ

【 摘 要 】

Abstract Throughout history, large tsunamis have frequently affected the Sanriku area of the Pacific coast of the Tohoku region, Japan, which faces the Japan Trench. Although a few studies have examined paleo-tsunami deposits along the Sanriku coast, additional studies of paleo-earthquakes and tsunamis are needed to improve our knowledge of the timing, recurrence interval, and size of historical and pre-historic tsunamis. At Noda Village, in Iwate Prefecture on the northern Sanriku coast, we found at least four distinct gravelly sand layers based on correlation and chronological data. Sedimentary features such as grain size and thickness suggest that extreme waves from the sea formed these layers. Numerical modeling of storm waves further confirmed that even extremely large storm waves cannot account for the distribution of the gravelly sand layers, suggesting that these deposits are highly likely to have formed by tsunami waves. The numerical method of storm waves can be useful to identify sand layers as tsunami deposits if the deposits are observed far inland or at high elevations. The depositional age of the youngest tsunami deposit is consistent with the AD 869 Jogan earthquake tsunami, a possible predecessor of the AD 2011 Tohoku-oki tsunami. If this is the case, then the study site currently defines the possible northern extent of the AD 869 Jogan tsunami deposit, which is an important step in improving the tsunami source model of the AD 869 Jogan tsunami. Our results suggest that four large tsunamis struck the Noda site between 1100 and 2700 cal BP. The local tsunami sizes are comparable to the AD 2011 and AD 1896 Meiji Sanriku tsunamis, considering the landward extent of each tsunami deposit.

【 授权许可】

Unknown