Development of a compound hazard risk index for natural and nuclear disasters and establishment of a prefecture-wide support system in Aomori

Background: Japan is highly susceptible to various disasters, as exemplified by the recent Noto Peninsula Earthquake. This study targeted Aomori Prefecture, located at the northernmost tip of Japan's main island, which faces the compound risks of natural and nuclear disasters. Methods: A vulnerability assessment was conducted for 108 medical institutions using a seven-item risk index to create a "pre-disaster list" (PL). Simulations based on Cabinet Office damage projections were integrated to develop a Hospital Support List (HSL). Results: The simulations revealed a potential need for the emergency evacuation of up to 2,859 patients. Critical vulnerabilities were identified across multiple indicators, including structural integrity, lifelines (power, oxygen, and water supply), and radiation protection systems. Conclusion: The findings indicate an urgent need to clarify the cooperative roles of Disaster Medical Assistance Teams (DMAT) and the Nuclear Emergency Medical Assistance Team (NEMAT). Establishing a comprehensive support system is essential for maintaining hospital functions and mitigating damage in future compound disasters.