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Abstract. Coastal areas face a significant risk of tsunami after a nearby heavy
earthquake. Comprehensive coastal port cities often complicate and intensify
this risk due to the high vulnerability of their communities and liabilities
associated with secondary damage. Accessibility to tsunami shelters is a key
measure of adaptive capacity in response to tsunami risks and should
therefore be enhanced. This study integrates the hazards that create risk
into two dimensions: hazard-product risk and hazard-affected risk.
Specifically, the hazard-product risk measures the hazard occurrence
probability, intensity, duration, and extension in a system. The
hazard-affected risk measures the extent to which the system is affected by
the hazard occurrence. This enables the study of specific strategies for
responding to each kind of risk to enhance accessibility to tsunami
shelters. Nagoya city in Japan served as the case study: the city is one of
the most advanced tsunami-resilient port cities in the world. The spatial
distribution of the hazard-product risk and hazard-affected risk was first
visualized in 165 school district samples, covering 213 km2 using a hot spot analysis. The results suggest that the rules governing the distribution
of these two-dimensional (2-D) risks are significantly different. By refining
the tsunami evacuation time–space routes, traffic-location-related
indicators, referring to three-scale traffic patterns with three-hierarchy
traffic roads, are used as accessibility variables. Two-way multivariate analysis of variance (MANOVA) was used to analyse the differences in these
accessibility variables to compare the 2-D risk. MANOVA was also used to
assess the difference of accessibility between high-level risk and low-level
risk in each risk dimension. The results show that tsunami shelter
accessibility strategies, targeting hazard-product risk and hazard-affected
risk, are significantly different in Nagoya. These different strategies are
needed to adapt to the risk.

AbstractTraditional studies of urban spatial expansion typically focus on a single vertical or horizontal dimension and rarely consider the two together. Using 58 cities in China as examples, this paper first identifies the urban growth pattern (UGP) of newly built‐up land patches in each city from 1995 to 2015 horizontally. It then compares and analyses the distribution patterns of three‐dimensional buildings in different UGP patches vertically. There were two important findings: (a) Building patterns in the outlying patches were characterized by low density, high floor numbers, and smooth changes. The infilling patches represented compact development and had the lowest average building height. Edge patches had the highest average number of floors, the most dramatic floor variability, and the lowest utilization rate of three‐dimensional space. (b) In western cities, building distribution characteristics in outlying patches were similar and formed clusters. The distribution characteristics of buildings in the Beijing‐Tianjin‐Hebei urban agglomeration edge patches, as well as those in the northeast urban agglomeration infilling patches, were similar, forming clusters of different types. The results of this paper will contribute to an understanding of both sprawl and the compact development of Chinese cities and will provide international comparative examples.