A 3800 year-long sedimentary record of tsunamis and hurricanes in Guadeloupe, Lesser Antilles

Le résumé fourni par la source

Guadeloupe is a tropical island in the central Lesser Antilles volcanic arc, exposed to both tectonic and climatic hazards. Subduction of the North American Plate beneath the Caribbean Plate and active shallow faulting generate earthquakes and potential tsunamis, while the island's tropical location subjects it to recurrent hurricanes causing severe coastal flooding. To understand these hazards, it is essential to determine their occurrence and frequency over long periods. Coastal lakes and lagoons preserve high-energy sedimentary deposits from past marine submersions, extending chronologies beyond the instrumental and historical records. This study examines sediment cores from two shallow coastal lakes at the eastern tip of Guadeloupe (∼1 km apart, Pointe des Châteaux): Pointe La Chaise (PLC), on the Caribbean Sea side, and Grande Saline (GDS), facing the Atlantic Ocean. Cores were imaged via X-ray computed tomography and analyzed using sedimentological, geochemical, and microfaunal proxies. Age models based on radiocarbon and short-lived radionuclides allowed correlation of recent deposits with historical events. Pointe La Chaise contains over 80 high-energy carbonate sand layers, whereas Grande Saline contains only four, indicating contrasting sensitivities to marine submersions. Two tsunami deposits were identified at both sites—the 1755 CE Lisbon tsunami and another around 1000 cal BP—along with three additional potential tsunami layers in Pointe La Chaise between 1700 and 2800 cal BP. Hurricane frequencies were reconstructed at Pointe La Chaise accounting for hiatuses caused by tsunamis and compared with regional records. Results support latitudinal migration of hurricane tracks across the Antilles, though the discontinuous sequences prevent a clear link with climatic forcing.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.