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On November 17, 2015 07:10:07 UTC a strong, shallow Mw6.5 earthquake, occurred on the island of Lefkada along a strike-slip fault with right-lateral sense of slip. The event triggered widespread environmental effects at the south and western part of the island while, the intensity and severity of these earthquake-induced deformations is substantially decreased towards the eastern part of the island. Relocation of seismicity and inversion of geophysical (GPS, InSAR) data indicate that the seismic fault runs parallel to the west coast of Lefkada, along the Aegean – Apulia plate boundary. The fault plane strikes N20 ± 5°E and dips to east with an angle of about 70 ± 5°. Coseismic deformation was measured in the order of tens of centimeters of horizontal motion by continuous GPS stations of NOANET (the NOA GPS network) and by InSAR (Sentinel 1 A image pairs). A coseismic uniform-slip model was produced from inversion of InSAR data and permanent GPS stations. The earthquake measured Mw = 6.5 using both the geodetic moment produced by the slip model, as well as the PGD relation of Melgar et al. (2015, GRL). In the field we observed no significant vertical motion of the shoreline or surface expression of faulting, this is consistent with the predictions of the model. The interferograms show a large decorrelation area that extends almost along all the western coast of Lefkada. This area correlates well with the mapped landslides. The 2003–2015 pattern of seismicity in the Ionian Sea region indicates the existence of a 15-km seismic gap offshore NW Cephalonia. [ABSTRACT FROM AUTHOR]

On January 26th and February 3rd, 2014, two earthquakes occurred onshore the island of Cephalonia inducing severe environmental effects. The main types of earthquake-induced failures were liquefaction and slope failures and were mainly widespread at the western and central part of the island at Paliki peninsula. Although the fact that the generated strong motions by the second event were the highest ever recorded in Greece, medium severity structural damages were induced. Few days after the occurrence of the events, two post-earthquake field surveys took place in order to document the generated environmental effects. By taking into account these field observations, it was decided to evaluate the macroseismic intensity of the February 3rd, 2014 earthquake by applying the ESI-07 scale. As an outcome, the epicentral intensity of Feb. 3rd, 2014 was evaluated as VII ESI-07 by taking into account the total affected area. Furthermore, as it is pointed out in primary contemporary sources and seismic catalogues, similar environmental failures such as liquefaction phenomena at coastal areas and large scale rockfalls were triggered by historical earthquakes at the island of Cephalonia. The most accurately described effects are the ones triggered by the 1867 earthquake. Therefore, it was decided to assess the macroseismic intensities of this historical event based on the ESI-07 scale and compare it with the relevant ones of Feb 3rd, 2014 event. As an outcome, it is concluded that similar intensities were assessed for both events, VIII ESI-07 for 1867 event and VII ESI-07 for the February 2014 one, despite the fact that the relevant earthquake magnitudes strongly differ. Outlining the results of this study, it is reconfirmed the importance of the recording and documentation of earthquake environmental effects in order to maintain the consistency with the historical earthquake catalogues. Moreover, a re-evaluation of historical earthquake magnitudes at the area of Cephalonia island could be realized in order to accurately update the seismic hazard. [ABSTRACT FROM AUTHOR]