Improving Tsunami Risk Analysis by Integrating Spatial Resolution and the Population’s Evacuation Capacities: A Case Study of Cartagena, Chile

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AbstractIntensive human activity in global coastal areas has led to increasing exposure to hazards. Cartagena Bay in Chile, an area with a long history of tsunami disasters, has undergone significant urbanization and experiences heavy tourist activity during the summer. While some studies have examined risk in Cartagena by focusing on hazard and vulnerability characteristics, challenges remain in delivering more spatially accurate studies and incorporating the population’s coping capacities. We undertook a tsunami risk assessment of Cartagena Bay that disaggregates social vulnerability to the census block level and assesses the inhabitants’ pedestrian evacuation potential through an agent-based model. Our findings indicate that urban coastal areas in Cartagena Bay might face substantial tsunami risk in a worst-case scenario, with 31.0% to 54.1% of its territory—depending on the scale of analysis—classified as high-risk areas. Of the examined urban blocks, 31.4% have average evacuation times exceeding 17 min (the critical time required by the tsunami to reach its run-up), and the most disadvantaged census block is 1,971.9 m away from its nearest shelter. We also demonstrated that a more spatially accurate vulnerability analysis is more conservative too. For instance, zones with high-risk levels decreased by 42.8% when the study scale moved from the block to the zone level of analysis. Similarly, areas with low risk increased by 80%. In comparison to previous studies, our findings show that tsunami risk in Cartagena Bay is significantly lower if coping capacities such as evacuation potential are included in the analysis.