Regional Vulnerability of the Tokyo Metropolitan Area to Flood and Earthquake Disasters

Abstract

Until the 1970s, the majority of flood disasters occurred in the lowlands to the east of Tokyo. In recent years, however, with the increasing frequency of localized torrential downpours – referred to as ‘guerrilla rainstorms’ – locally concentrated, devastating damages have been suffered. With respect to measures against such damages, underground reservoirs and rivers are being constructed. As a soft measure, flooding hazard maps are being made public. Because of its densely concentrated urban structure, the Tokyo Metropolitan Area is also at high risk of fires and building collapses during earthquakes. Furthermore, a large-scale earthquake is expected to occur there in the near future. As mitigation measures, earthquake-proof reinforcement is being subsidized and disaster prevention activities and education are being conducted by community organizations. Although a variety of disaster prevention measures against floods and earthquakes are being conducted in the Tokyo Metropolitan Area, lowland areas could still suffer serious damage due to their densely concentrated urban structure. Since disasters affect society as a whole, vulnerability can be defined not only by such urban structure and mitigation measures, but also by the pre-disaster welfare state of individual households, capacity of administrative bodies and cooperation within them. Thus, we should clarify the respective roles of affected individuals, areas, and administrative bodies so that they complement each other. However, even administrative responses to disasters (rescue and assistance) have limits. Therefore, individuals should be prepared to protect their own lives and assets (self-help) and respond cooperatively in collaboration with their neighbours.