Sedimentary records of tsunamis and hurricanes in the Lesser Antilles

Abstract:

The Lesser Antilles are a densely populated region exposed to many coastal hazards such as hurricanes and tsunamis. However, the historical catalog of these events is too short to allow risk assessment and return period estimations, and it needs to be completed with long-term geological records. Sediment cores were sampled in March 2018 in small coastal lagoons on Scrub, Anguilla, Barbuda and Guadeloupe Islands (North Eastern Caribbean). Sedimentological, geochemical, microfaunal and chronological analyses enabled us to identify sandy layers resulting from high energy marine floods. One sandy layer identified on Scrub, Anguilla and Guadeloupe Islands is associated with the transatlantic tsunami triggered by the 1755 AD Lisbon earthquake. A very thick sandy layer recorded in Scrub lagoon is dated at 1415 cal. AD (1364-1469 cal. AD). This event was recorded in both the northern and the southern part of the Caribbean, with its large extent supporting a tsunamigenic origin. Most of the remaining sandy layers are interpreted as resulting from hurricanes. The most recent layers are associated with historical hurricanes. A 1600 year-long hurricane chronicle has been reconstructed in Scrub Island and compared to already published hurricane sediments records. This new chronicle displays similarities with that of the Bahamas and is in antiphase with that of the North Eastern US coast. This regional comparison may evidence a climate forcing of the hurricane tracks through time.