Erosion and Deposition due to the Tsunami caused by the Chile Earthquake on May 24, 1960

The problems related with erosion and deposition due to the Tsunami caused by the Chile Earthquake on May 24, 1960 are briefly summarized in this report. The area where observations were made is the Takada-Matsubara beach and the vicinity in Iwate Prefecture. Waves cussed by the Tsunami like oceanic waves and currents, is an important agency in modifying the geomorphological features of the land adjacent to the sea. This agency is subdivided, from its process, into three types of streams, namely, sheet-flow, linear-flow and eddy. Each of the processes is described on the observed features and are accompanied with illustrations. Degradation and aggradation due to the Tsunami changes the landform by erosion, masswasting and deposition. These different processes, related with the three types of agencies above-mentioned, are discussed and accompanied with illustrations. The Takada-Matsubara beach and bay-head bar of the Hirota Bay along the Sanriku coast of Iwate prefecture was damaged by and due to the after effects of the Tsunami. The beach extending from Wakinosawa to the Kesen River was cut into three parts, and the lagoon of Furukawa-numa, situated behind the bay-head bar, became united directly with the Hirota Bay. The erosional processes and the deposits in the vicinity of the Takada-Matsubara beach are elucidated by the accompanying illustrations.