A Multi-Agent Simulation of Evacuation Behavior toward Tsunami Shelter Buildings: A Geographical Study Conducted in Central Kushiro, Hokkaido

Abstract

Kushiro town center is expected to experience a major tsunami in the future. This study used a multi-agent simulation comprising walking residents to elucidate the changes in the spatial patterns of tsunami shelter buildings in this location and examined their effectiveness as well as difficulties. The conducted simulation modeled residents in a district with no high-rise buildings. The behavior of residents was assumed as a horizontal movement toward tsunami shelter buildings located in residential neighborhoods where they would access the top floor via stairs. Tsunami inundation projections for this region were updated after the Great East Japan Earthquake. As a part of the tsunami countermeasure, multiple high-capacity shelters were constructed. The results of this study confirmed that such efforts improved the evacuation environment. However, the simulation also revealed that residents of areas distanced from the tsunami shelters would slow down on climbing stairs, and walking would likely to be obstructed near the stairs. These people would find it difficult to reach the upper floors of the buildings by the time the tsunami arrives. Therefore, the study results indicate that the effectiveness of tsunami shelters should not be judged solely by their holding capacities; rather, their usefulness should be evaluated by the number of evacuees they can accommodate before the tsunami hits. This scope was estimated by considering the horizontal and vertical movements of the residents, and the simulation outcomes evinced that the study method was apt for the performed appraisal.