Probabilistic analysis of the vulnerability of fire departments to ignitions following megathrust earthquakes in the Nankai Trough subduction zone, Japan

摘要

This study investigates the variability of the number of ignitions following hypothetical Nankai Trough earthquakes for municipal fire departments across Japan. An empirical equation for predicting the number of ignitions following earthquake was used in combination with an empirical ground motion prediction equation. 72 hypothetical earthquake scenarios were considered by varying earthquake magnitude, source area, and season and hour of occurrence. The conditional exceedance probability curve of the number of ignitions following earthquake was estimated for each municipal fire department in order to investigate how frequently the number of ignitions exceeds the firefighting capability (here, the number of fire engines divided by 3) when all possible earthquake scenarios are considered. For 27 in 731 municipal fire departments, the number of ignitions was presumed to exceed the firefighting capability with a probability of 10% or more. Therefore, measures need to be taken, such as enhancing firefighting capability, installing household ignition prevention devices, and reducing densely built-up areas, because of the concern that some of ignitions may develop into large-scale urban fires. The results are useful for understanding of the vulnerability of municipal fire departments to ignitions following a future Nankai Trough earthquake and improving preparedness.