Abstract
We estimated tsunami mitigation effects of coastal forest, multiple countermeasures, and its combination by tsunami numerical analysis and actual damage data in Iwanuma City. Our results demonstrated that coastal forest could delay the tsunami arrival time at around the Sendai-Tobu Road by a maximum of three minutes. Reduction of building damage probability and fatality ratio in all areas other than Yanome District can be confirmed. Furthermore, scenarios focused on a multiple defense system were also considered in our hazard assessment. As results, the current multiple defense system shows tsunami mitigation effect. Configurations and combinations of the multiple defense system could increase the mitigation effect. Tide embankment decreases inundation of tsunami, and hill decreases flow velocity of the rear. Multiple defense system utilizing these characteristics with the combination is effective for tsunami mitigation.
