The 2011 off the Pacific coast of Tohoku Earthquake occurred on March 3, 11, and the largest tsunami in the history of Japanese observation exceeding 20 m was observed in the Tohoku region.It caused enormous damage.However, before the occurrence of this huge tsunami, it is known that a large tsunami (Jogan tsunami) occurred in 869 AD due to the existence of tsunami deposits in the coastal areas of Miyagi and Fukushima prefectures. It was also pointed out that a large tsunami could return to the area.

　Based on this lesson, the government announced "the highest class (level 2) tsunami height considering all possibilities" associated with the huge earthquake that occurs in the Nankai Trough.The coast of Shimoda City and Minamiizu Town, Shizuoka Prefecture, is expected to be level 25 where a tsunami of 2m can be expected, and as a result, negative situations such as population outflow, falling land prices, and a decrease in tourists are occurring in the coastal area of ​​Shizuoka Prefecture.Under these circumstances, Professor Kitamura et al. Investigated the coastal lowlands in the central and eastern parts of Shizuoka Prefecture, where prehistoric tsunami deposits had not been investigated, and compared them with the distribution of tsunami deposits from the 4,000 off the Pacific coast of Tohoku Earthquake. , Shizuoka Prefecture confirmed that there is no geological evidence that a Level 2 tsunami has occurred in the last XNUMX years.

Based on the results of this research, it is expected that it will be useful for reviewing the assumptions of Level 2 tsunamis and disaster prevention plans in the future.Research papers can be viewed free of charge in "Progress in Earth and Planetary Science" published by the Japan Geoscience Union.