Late-Holocene shoreline changes related to palaeoseismic events in the Ionian Islands, Greece

Abstract

A systematic multidisciplinary survey on the coasts of the Ionian Islands, founded on 26 new radiocarbon accelerator mass spectrography (AMS) dates, has revealed the occurrence of sectors which were uplifted (seismo)tectonically during the late Holocene. In Corfu, two uplift movements of about 0.8m each took place in the central part of the island: one of them around 790-400 cal. BC, and also at a more recent, undetermined date. In Levkas, up-and-down tectonic movements of metric order governed late-Holocene relative sea-level changes, at least in the northern part of the island; submergence of at least 2.5 m occurred since 2400 years ago, with a possible spasmodic subsidence around cal. AD 500-700. In Cephalonia, two vertical displacements affected most of the island, around cal. AD 350-710 and in AD 1953; both movements resulted in uplift in the southeastern part of the island. Submergence seems to predominate round Ithaca. Lastly, in Zante, clear evidence of a Holocene crustal block movement is limited to the southeastern peninsula, where an uplift of 0.95 ± 0.15 m took place, probably coseism ically, around the period cal. AD 200-500. The time ranges of uplift in Cephalonia and Zante, and of possible subsidence in Levkas, correspond with a period of regional tectonic paroxysm, between the middle of the fourth century AD and the middle of the sixth century AD; this has already been documented in several areas of the eastern Mediterranean, notably in the Gulf of Corinth, the southern Hellenic arc, Turkey, Cyprus, the Lebanon and Syria.