Sand Waves in Kesennuma Harbour

Abstract

Kesennuma harbour suffered a great damage caused by the Chilean Tsunami of May 24, 1960. Erosion caused by the Tsunami in this harbour was remarkable at the narrow water-way near Hatigasaki in particular. There are sand waves aligning transverse to the direction of the narrow water-way in the eroded area, according to the results of detailed survey which was made just after the Tsunami. The length of sand wave near Hatigasaki attained 20 meters, and amplitudes 1.5 meters. The group on the shallow sea bottom to the southeast of Hachigasaki was less than 5 meters in length and 0.5 meters in amplitude. It is likely that the sand waves were formed by the secondary current of the Tsunami which flowed west to east near bottom and were caused by the curvature of the narrow water-way.