The February 2014 Cephalonia earthquake (Greece): 3D deformation field and source modeling from multiple SAR techniques

On 26 January 2014 at 13:55 UTC, an Mw 6.0 earthquake struck the island of Cephalonia, Greece, followed five hours later by an Mw 5.3 aftershock and by an Mw 5.9 event on 3 February 2014 at 03:08 UTC (National Observatory of Athens, Institute of Geodynamics [NOA-GI]). The epicenter of theMw 6.0 event was relocated 2 km east of the town of Lixouri, and that of the Mw 5.9 event at the tip of the Gulf of Argostoli, in the northern part of the Paliki peninsula (Fig. 1; Karastathis et al., 2014; Papadopoulos et al., 2014). Extensive structural damage and widespread environmental effects were induced throughout the Paliki peninsula and along the eastern coast of the Gulf of Argostoli (Valkaniotis et al., 2014). Quays, sidewalks, and piers were damaged in the waterfront areas of the towns of Lixouri and Argostoli, the island capital, and liquefactions, road failures, rock falls, and small landslides were observed.Most of the latter effects took place in the aftermath of the 26 January 2014 event and were reactivated one week later by the 3 February earthquake. In this paper, we derive the 3D surface deformation field associated with the 3 February 2014Mw 5.9 event based on the application of three different measurement techniques to Synthetic Aperture Radar (SAR) acquisitions from the Italian Space Agency (Agenzia Spaziale Italiana [ASI]) COSMO– SkyMed satellites and the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, DLR) Tan- DEM-X satellite. We then model the main seismic sources and their associated slip distributions, comparing the latter with improved hypocenter relocations, which allows us to speculate on the possible rupture mechanism. Finally, we discuss the contribution of our findings to the characterization of the seismogenic sources of this region.