Natural hazards in La Réunion island (France) since the mid-seventeenth century: production and analysis of a geohistory database (HistoRiskRun)

Abstract. La Réunion is one of the French territories most exposed to natural risks. The island is exposed to seven major natural hazards: cyclones, floods, swells and tsunamis, landslides, earthquakes, wildfires, and volcanic eruptions. Numerous natural disasters have occurred on the island, as well as less significant natural events. This study presents a historical review of the direct impacts of natural events documented in departmental and national archives since human settlement on the island. Thus, in total 2,823 sources, referencing 1,266 events from 1655 to 2025 have been processed. The source's reliability is analyzed using a decision tree method. Based on the impacts, significance scores for each referenced event is established. An analysis of the evolution of impacts and mortality over time is conducted. A detailed geodatabase (HistoRiskRun) is created to capitalize information about natural hazards in La Réunion since its colonization. This database enhances documentation and understanding of past events and the evolution of risk management over time. This work provides elements to discuss the temporal evolution of impacts and mortalities associated with natural hazards and to relate these dynamics to the island’s geo-socio-historical context.