Late Holocene tsunamogenic coseismic uplift in Kerkira Island, Greece

The presence of a coralligenic-like bioherm constituted by boulders up to 1.2 m in diameter cemented by bioconcretions of calcareous algae and Vermetids spp. has been recognized in the southernmost part of Kerkira Island. This biostructure is placed at up to ∼1.4 m above the present mean sea level. A few hundred meters north, well developed beach rocks are at about the same elevation. The morphological continuity of these landforms allows us to hypothesize that a recent coseismic uplift interested this area. AMS age determination has been performed on different Vermetids sampled in the upper part of the raised bioherm. Moreover, a complete review of the chronological data cited in the bibliography highlights the difficulties in the use of some bioindicators as chronologically precise sea level indicators. The entire data set suggests a Late Holocene tectonic behaviour characterized by sequences of subsidence and coseismic uplift. In particular, the age of the raised bioherm suggests that a coseismic uplift occurred ∼3 ka BP due to an earthquake of regional interest capable of generating a strong tsunami that impacted the nearest coast of Lefkada Island and the Plaghia Peninsula.