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Characteristics of Tsunami Damage to the Tide Walls in Iwate Prefecture from the Great East Japan Earthquake



Author(s)

Tetsuya Oyamada, Shunsuke Hanehara, Hideaki Deto and Shoji Iwasaki

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DOI:10.17265/1934-7359/2014.07.001

Department of Civil and Environmental Engineering, Iwate University, Iwate 0208551, Japan

This research paper describes the tsunami damage to tide walls observed using aerial photographs and field investigations at 13 locations along the coast of Iwate Prefecture, where significant tsunami damage occurred as a result of the Great East Japan Earthquake. This paper also summarizes the characteristics of the damage. The tide walls in Iwate Prefecture were constructed on a ria (hilly type) coast, this geographical feature of Iwate being different from that of the other disaster areas, primarily Miyagi and Fukushima Prefectures. The results of our investigations show that all the devastated tide walls suffered from overflow before being damaged. In particular, the sloping and vertical type tide walls with slope protection were damaged by scouring of the infill sand or back fill soil due to the overflow of the tsunami. In the case of vertical type tide walls without slope protection, damage was caused by scouring of the back fill soil.

Tide wall, Great East Japan Earthquake, tsunami.