Kazuya Sakai, Takaaki Uda, Toshiro San-nami, Tatsuya Shimizu


A great earthquake with a magnitude of 9.0 occurred on March 11, 2011, with an epicenter 130 km offshore of the Oshika Peninsula in Miyagi Prefecture. After the earthquake, a giant tsunami inundated a large area along Japan’s eastern coastline. We carried out field observations to investigate the damage to Arahama Town and the formation of a trench as a result of local scouring by the jet flow over the coastal dike. Here, the results of the field observations on the inundation of the tsunami into a wide residential area on Shobuta Beach and in Arahama Town were reported. Then, the destruction of the coastal dike, as well as the formation of a large trench immediately behind the coastal dike due to the tsunami overflow on the Yamamoto coast, was investigated, where the tsunami height reached up to 19.2 m above mean sea level (MSL), estimated from the run-up height on the slope of a hill.


2011 Great Tsunami; tsunami damage; trench formation; coastal dike; coastal forest

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Harada, K., T. Aburaya, L. Hamzah, and F. Imamura. 2000. Examination of the effect of control forest to reduce a Tsunami energy, J. JSCE, Ser. B2 (Coastal Eng.), 47, No.1, pp. 366-370. (in Japanese)

Joint Research Group of 2011 Great Tsunami of JSCE. 2011. http://www.coastal.jp/ttjt/, August 20, 2011.

Murai, H., M. Ishikawa, J. Endo, and R. Tadaki, ed. 1992. Japan's Coastal Forest, Soft Science Co., Ltd. (in Japanese)

Public Works Research Center. 2011. Tsunami report: http://pwrc-nagisa.jp, 2011, March 1, 2012. (in Japanese)

Shibayama, T. 2011. Field survey of the 2011 off the Pacific Coast of Tohoku Earthquake Tsunami disaster and future tsunami protection, Proc. 6th Inter. Conf. on Asian and Pacific Coasts, pp. 79-82.

Shibayama, T., R. Matsumaru, H. Takagi, M. Esteban, and T. Mikami. 2011. Field survey of the 2011 off the Pacific coast of Tohoku earthquake tsunami disaster in the south of Miyagi prefecture, J. JSCE, Ser. B2 (Coastal Eng.), 67(2), pp. I_1301-I_1305. (in Japanese)

Tanaka, H., A. Mano, and K. Udo. 2011. Beach morphology change induced by the 2011 great east Japan earthquake tsunami, J. JSCE, Ser. B2 (Coastal Eng.), 67(2), pp. I_571-I_575. (in Japanese)

Uda, T., K. Sakai, T. San-nami, and T. Shimizu. 2012. Two distinguished effects of the 2011 Great

Tsunami to the coasts along Sendai Bay - Damage to Arahama and trench formation behind the dike on Yamamoto coast, Trans. Jp. Geomorphological Union, 33. (in press)

DOI: https://doi.org/10.9753/icce.v33.currents.13