Enhancing tsunami evacuation strategies in Puerto Rico using open-source least-cost path analysis

Abstract Effective disaster planning strengthens community resilience and reduces both damage and casualties from tsunamis. In Puerto Rico, municipal emergency management planners need data on the tsunami evacuation zone (TEZ), wave run-up heights, and estimated evacuation times to inform constituents. There are 46 coastal municipalities within the TEZ. Due to evolving methodologies, software, and staffing, the Puerto Rico Seismic Network’s TsunamiReady Program has only provided walking-time estimates to a subset of communities. This study introduces an effective, repeatable methodology to generate distance to safety and pedestrian evacuation times across all impacted zones. The approach—an iterative least-cost path analysis from road points to safety areas, followed by spatial interpolation—produced evacuation time maps for all 46 municipalities. The longest modeled evacuation time was 184 min in Loíza, though average times across most municipalities were under 35 min. For comparison, historical tsunami evidence suggests that waves can reach Puerto Rico’s western coast within 2 to 45 min of a generating event. The open-source methodology used here is transferable to other tsunami-prone regions and offers significant advantages over proprietary systems. The results provide Puerto Rico’s emergency managers, and the public, with essential spatial information to identify the highest-risk portions of their TEZ and improve evacuation planning.