1600 year-long sedimentary record of tsunamis and hurricanes in the Lesser Antilles (Scrub Island, Anguilla)

The Lesser Antilles are a densely populated and a very touristic region exposed to many short-term 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. Two sediment cores were sampled in March 2018 in a small coastal lagoon on Scrub Island (north eastern Caribbean). Here, we present sedimentological, geochemical, microfaunal and chronological analyses that enabled us to identify 25 sandy layers resulting from high energy marine floods. Two of these layers were interpreted as tsunami deposits based on sedimentological and geochemical evidence. The most recent deposit is associated with the transatlantic tsunami triggered by the 1755 AD Lisbon earthquake. The older is the thickest sandy layer recorded in the lagoon and 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. The 23 remaining sandy layers were interpreted as resulting from hurricanes, with the three most recent layers being associated with historical hurricanes. This new 1600 year-long reconstructed chronicle, has been compared to other published hurricane chronicles from the region. Scrub chronicle is the most eastern site and displays similarities with that of the Bahamas, while it is in antiphase with that of the north eastern US coast. This regional comparison may provide evidence of a latitudinal forcing for the hurricane tracks through time in relation to climate fluctuations.