Date(s) - 17/03/2016
4:00 pm - 4:45 pm
“The record of past climates in tsunami deposits”
Presented by Christophe Lécuyer
Earthquakes and explosive eruptions generate tsunami waves at the origin of thick and chaotic coastal sediments. These commonly fossiliferous deposits are formed instantaneously within historical or geological timescales, and therefore have the potential to provide snapshot records of past climates. In Crete, near Palaikastro, a thick sedimentary layer (1 to 9m) was deposited by huge tsunami waves (~10m). Volcanic ash, the geometry, and archaeological and faunal contents of the sedimentary deposit along with radiocarbon dating indicate that the tsunamite was coeval with the Minoan Santorini (Thera) eruption 3,350 years BP. The devastating tsunami wave deposited large rocky blocks and a muddy matrix containing diverse faunas (marine molluscs, cattle skeletons) and artefacts from the Minoan civilization. Oxygen isotope measurements of both marine shells and terrestrial vertebrate teeth and bones revealed that sea surface and air temperatures were higher than today (~2°C), but with similarly warm summers (26°C) and much milder winters (16°C). The eruptions and tsunami events are also discussed in the context of the fall of the Minoan civilisation.