Overview of the 2011 Tohoku Earthquake Tsunami Damage and Its Relation to Coastal Protection along the Sanriku Coast

Abstract

At 14:46 local time on 11 March 2011, a magnitude 9.0 earthquake occurred off the coast of northeast Japan. The very large local tsunami heights and damage to coastal structures and other civil infrastructure were strongly dependent on the location. To verify the effectiveness of several types of tsunami protection strategies, we analyzed three typical areas from the Sanriku ria coast. Detailed survey data are shown with photographs and are discussed with regard to severity of damage and tsunami event. The roles of offshore tsunami breakwaters and coastal forests are discussed for severe tsunami, which exceeds 10 m near the coast. The survey observations and results from numerical calculations clearly indicate the reduction of tsunami damage due to an offshore barrier in Kamaishi Bay.