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

Abstract

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 This is a non-peer reviewed preprint submitted to EarthArXiv The manuscript is under review at Sedimentary Geology 2 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.

Interaction Between Climate and Tectonics in the Northern Lesser Antilles Inferred From the Last Interglacial Shoreline on Barbuda Island

“…This suggests that LIG markers have been uplifted in Barbuda. Moreover, no LIG RSL indicator is found at comparable altitude on the western side of the island where the main morphological feature is a lagoon filled by several meters of sediments (Bain et al, 2010;Biguenet et al, 2020). This indicates that the RSL markers of the LIG underwent vertical deformation after their deposition, as previously suggested by Russell and McIntire (1966).…”

Tsunamites versus tempestites: Various types of redeposited stromatoporoid beds in the Devonian of the Holy Cross Mountains (Poland), a case study from the Ołowianka Quarry

“…As mentioned above, selected features of the stromatoporoid beds can be interpreted both with regards to the original stromatoporoid habitats and the high-energy processes leading to their transport and redeposition. Clear differentiation between the two beds suggest that the thick allobiostromal bed ultimately arose from a tsunami, while the parabiostrome is a more typical storm tempestite; Various methods of distinguishing tsunamites from tempestites in the geological record have been discussed by many authors [ 82 – 91 ], including in studies of modern examples [ 92 – 97 ]. This task has proven to be complicated, and according to some authors, utterly impenetrable.…”

A Megathrust earthquake as source of a Pre-Colombian tsunami in Lesser Antilles: Insight from sediment deposits and tsunami modeling

“…Figure13show the results of run-up on the islands of Anegada and Scrub with four profiles of maximum water heights and flowJ o u r n a l P r e -p r o o fJournal Pre-proof velocities obtained for models T1, T2, OR1, OR2, OR3 and OR4.a) Analysis of simulation results on Anguilla and Scrub IslandsThe tsunami simulations on the area of Anguilla and Scrub were performed on 5 m-resolution grids and the two lagoons where sediment cores were sampled are mapped with 1 mresolution grids. We extracted the values at the coordinates of the two ponds where tsunami deposits have been identified(Biguenet et al, 2020. In Figure9, Scrub1 gage is located in Scrub bay, next to the lowest sand barrier's topographic height (northern part) and Scrub2 gage is located in the bay in front of the central part of the barrier.…”