Strategies for increasing tsunami shelter accessibility to enhance hazard risk adaptive capacity in coastal port cities: a study of Nagoya city, Japan

Abstract

Abstract. Coastal areas face a significant risk of tsunami after a nearby heavy\nearthquake. Comprehensive coastal port cities often complicate and intensify\nthis risk due to the high vulnerability of their communities and liabilities\nassociated with secondary damage. Accessibility to tsunami shelters is a key\nmeasure of adaptive capacity in response to tsunami risks and should\ntherefore be enhanced. This study integrates the hazards that create risk\ninto two dimensions: hazard-product risk and hazard-affected risk.\nSpecifically, the hazard-product risk measures the hazard occurrence\nprobability, intensity, duration, and extension in a system. The\nhazard-affected risk measures the extent to which the system is affected by\nthe hazard occurrence. This enables the study of specific strategies for\nresponding to each kind of risk to enhance accessibility to tsunami\nshelters. Nagoya city in Japan served as the case study: the city is one of\nthe most advanced tsunami-resilient port cities in the world. The spatial\ndistribution of the hazard-product risk and hazard-affected risk was first\nvisualized in 165 school district samples, covering 213\u2009km 2 using a hot spot analysis. The results suggest that the rules governing the distribution\nof these two-dimensional (2-D) risks are significantly different. By refining\nthe tsunami evacuation time–space routes, traffic-location-related\nindicators, referring to three-scale traffic patterns with three-hierarchy\ntraffic roads, are used as accessibility variables. Two-way multivariate analysis of variance (MANOVA) was used to analyse the differences in these\naccessibility variables to compare the 2-D risk. MANOVA was also used to\nassess the difference of accessibility between high-level risk and low-level\nrisk in each risk dimension. The results show that tsunami shelter\naccessibility strategies, targeting hazard-product risk and hazard-affected\nrisk, are significantly different in Nagoya. These different strategies are\nneeded to adapt to the risk.