Vol. 60, n.1, March 2019
Coastal deformation in Lefkada Island associated with strong earthquake occurrence
V. Karakostas, E. Papadimitriou, P. Patias and Ch. Georgiadis
Received: 13 November 2018; accepted: 22 January 2019
The Lefkada Island, central Ionian islands, Greece, deforms in response to rapid dextral strike-slip movement of the Cephalonia Transform Fault Zone accounted to 2-3 cm/yr. Historical and instrumental earthquakes had a major impact on the coastal landscape, as they had caused nearshore landslides, rockfalls, tsunami-induced flooding, and several centimetres coastal uplift and subsidence. Appreciable coseismic displacements were calculated at discrete points designating the coastlines after applying an elastic model and considering the coseismic slip of the 2003 (M 6.3) and 2015 (M 6.5) Lefkada earthquakes, and the 2014 Cephalonia Island doublet (M 6.1 and M 6.0), the latter being of negligible importance. Subsidence and uplift of several centimetres were calculated along the western Lefkada coastline, depending upon the position of the calculation point relative to the causative rupture and permanent localised uplift for certain areas. For the eastern Lefkada coastline, the coseismic slips resulted in unremitting subsidence. The respective horizontal coseismic coastal displacements were more profound, consistent with the predominant strike-slip movement. The calculations along with the historical macroseismic effects comprise the basis for both the countermeasures related to coastal preservation and mitigation of the seismic risk from landslides and rock falls that appear in synchronization with the coseismic slip.
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