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In the case of near-field tsunami emergencies, evacuation is considered the most important and effective method to save human lives. While significant efforts have been carried out to examine the relationships between urban forms and tsunami evacuation, challenges remain on delivering evidence-based urban design strategies, principles or metrics that could be applied by decision-makers to guide the physical development or retrofitting of tsunami-prone coastal communities around the world. In this paper, we propose a methodology that combines tsunami flood and evacuation modelling with statistical analysis, to examine the pedestrian evacuation potential of 67 urban samples extracted from 12 case studies in Chile. Our findings show that urban form parameters like the number of exit points out of an endangered area, the mean distance from the street network to these points, and the population density, can have a noticeable impact on tsunami evacuation times, which nonetheless is significantly dependent on the evacuees’ departure time. Moreover, we demonstrate that Chilean urban coastal development has been noticeably carried out through grid-like form patterns that might contribute to hinder evacuation in case of a tsunami emergency.

This article addresses the topic of tsunami risk in the context of early warning and response. We examine how zoning schemes can promote or mitigate intensive densification processes in locations exposed to natural hazards, and how this can lead to increased risk in urban areas. We introduce a tsunami risk index for the Poblacion Vergara neighborhood in the city of Vina del Mar, Chile, through a longitudinal study that combines population-related census data (1992–2017) and zoning provisions, tsunami flood modeling and evacuation modeling into a GIS-based model. The purpose of the study is to examine how recent substantial changes in population density have led to increased tsunami risk conditions in one of the most sought-after locations in the Greater Valparaiso Metropolitan Area and how these conditions are related to current and previous zoning schemes. The results show an overall significant increase in tsunami risk conditions over the course of the examined census interval. This work can contribute to a better understanding of how residential densification (fostered by real estate-driven development and permissive zoning schemes) can exacerbate tsunami risk in other coastal cities in Latin America and the world.