Decision-making support utilizing real-time tsunami inundation and damage forecast

In the Great East Japan Earthquake of 2011, tsunami inundation caused devastating damage over a wide area along the coast of the Tohoku region. Since then, hazard maps for tsunami flooding have been prepared or updated nationwide. These maps assume flooding in the event of a tsunami of the extreme class (L2) with a recurrence interval of 1000 years, in which the top priority is to protect lives. However, once an earthquake occurs, the situation of inundation differs depending on the earthquake rupture mechanisms and its magnitude, so the area of unexpected damage needs to be grasped as soon as possible. Therefore, a forecast of tsunami inundation and damage needs to be provided immediately after the disaster to support disaster responders' decisions. In this paper, we propose a framework to utilize a tsunami inundation and damage forecast. Specifically, we introduce "recovery levels", which allow areas that need immediate response to be more easily recognized to allocate human and physical resources. We evaluated their usefulness from the viewpoint of disaster responders by surveying users in a local government through a disaster response drill and an explanatory meeting. Consequently, it was found that the recognition and understanding of the tsunami forecast advanced, and many positive opinions were obtained about utilizing the forecast in the initial activity of disaster response.