Geo-scientific evidence of tsunami impact in the Gulf of Kyparissia (western Peloponnese, Greece)
Willershäuser, Timo; Vött, Andreas; Hadler, Hanna; Fischer, Peter; Röbke, Björn; Ntageretzis, Konstantin; Emde, Kurt; Brückner, Helmut
published: Dec 1, 2015
In this study, we present geo-scientific evidence of repeated tsunami impact on the coastal low- lands of the Gulf of Kyparissia between Cape Katakolo and Lake Kaiafa. As known from literature and previous geo-scientific studies along the coasts of the eastern Ionian Sea, tsunami influence in the area is a strong and dominant factor in the overall coastal evolution. We combined sedimentological, geomor- phological and geophysical studies with geochemical and micropalaeontological analyses to reconstruct the palaeoenvironmental evolution of the former Mouria Lagoon near Aghios Ioannis and adjacent areas, namely around Kato Samiko and the former Agoulenitsa Lagoon. Our main objective was to look for traces of palaeotsunami impact with the sedimentary records of different coastal geo-archives. In the area of the former Mouria Lagoon we found four distinct allochthonous sediment layers of tsunamigenic ori- gin that are at least traceable up to 2 km inland from the present day coastline. Three of the high-energy events caused major environmental changes and obviously lead to massive modifications of the palaeo- coastline. Moreover, our results show that the local relative sea level rise has its maximum at present and has never been higher during the Holocene. High-energy deposits encountered near Kato Samiko are characterised by strongly unsorted sediments including marine shell debris mixed with abundant archaeological remains deposited on top of an erosional unconformity. Here, high-energy sediments occur as channel deposits out of allochthonous coarse-grained sediments that are clearly detectable by the combination of electrical resistivity measurements and terrestrial vibracoring. The local event-geochro-nostratigraphy was realised by radiocarbon dating and shows that a first tsunami event hit the Mouria Lagoon and probably also the coastal plain of Kato Samiko in the 5th millennium BC (tsunami generation I). A second tsunami event was dated to the mid to late second millennium BC (tsunami generation II) while tsunami generation III took place between the 1st cent. BC and the early 4th cent. AD. Tsunami generation IV is most probably related to one of the well-known tsunami events that affected wide areas of the eastern Mediterranean in 365, 521 or 551 AD.