Damage along coasts in Sendai Bay caused by 2011 Great Tsunami

Abstract

A great earthquake with a magnitude of 9.0 occurred on March 11, 2011, at 14:46 with the epicenter 130 km offshore of Oshika Peninsula in Miyagi Prefecture. Such a large earthquake had never been experienced before in Japan’s history of earthquake observation. After the earthquake, a large-scale tsunami was generated by abrupt crustal subsidence and elevation, which inundated the coasts of east Japan; in particular, severe disaster occurred along the coasts in Iwate and Miyagi Prefectures. On April 20 and August 12, 2011, we carried out field observations to evaluate the effect of the tsunami disaster along the coasts in Sendai Bay. During these field observations, the following specific features of tsunami damage were observed in the Arahama Region and on the Yamamoto coast, as shown by rectangular regions in Fig. 1: the inundation of the tsunami into a wide residential area in the Arahama Region and the destruction of the coastal dike as well as the formation of a large channel behind the coastal dike due to tsunami overflow on the Yamamoto coast, where the tsunami height reached up to 20 m above mean sea level (MSL), determined as the run-up height on the slope of a hill. In this study, the results of the field observations are reported.