Community-level tsunami risk hotspot screening in the Caribbean Basin using composite ranking indices and open data

This study develops a standardised, reproducible, and operational methodology to screen tsunami risk at the community scale across the Caribbean Basin, based exclusively on open and globally consistent datasets. Evacuation demand is quantified using three indicators: population size, the proportion of inhabitants within the evacuation zone, and the proportion of the administrative area to evacuate. Tsunami hazard is characterised using the CATSAM scenario database, providing maximum modelled coastal wave amplitudes from harmonised, expert-defined tsunami scenarios. These components are combined into composite indices of evacuation needs (TENI), tsunami hazard index (THI), and overall tsunami risk (TRI).

Rather than constituting a fully probabilistic disaster risk assessment, the TRI is designed as a first-order operational screening index and a relative comparative indicator intended to support regional-scale preparedness prioritisation. Applied to 920 coastal communities, the framework identifies strong spatial contrasts, with approximately 8.1 million people located within tsunami evacuation zones. Results show that some small island and coastal communities exhibit disproportionately high evacuation needs, while exposure to high tsunami amplitudes is concentrated in specific sub-basins. The TRI enables the identification of a limited set of high-priority communities concentrating a disproportionate share of the regional evacuation burden. The methodology is fully reproducible and transferable to other tsunami-prone regions and provides a robust decision-support tool for evacuation planning and the implementation of the IOC-UNESCO Tsunami Ready Recognition Programme.