The Mw6.5 17 November 2015 Lefkada (Greece) Earthquake: Structural Interpretation by Means of the Aftershock Analysis

On the Segmentation of the Cephalonia–Lefkada Transform Fault Zone (Greece) from an InSAR Multi-Mode Dataset of the Lefkada 2015 Sequence

“…The dip angle was grid searched in terms of the lowest root-mean-square (RMS) values, which were obtained for dips in the range 80 • to 90 • , with the lowest values indicating a vertical fault. This is in accordance with Papadimitriou et al [21], which state that the aftershock locations possibly indicate a vertical structure at that specific area. Results of the nonlinear inversion are summarized in Table S1 and uncertainties are shown in Figures S6 and S7.…”

“…Our radar signal provided more insights on the on-land deformation pattern of both islands, and as a consequence, it offered better constraints regarding the fault segmentation. We further investigated the multi-segment hypothesis, and building upon the study of Papadimitriou et al [21] we were able to present a new fault segmentation that predicts well all the InSAR displacement data (both ascending and descending), which is at the same time justified by the relocated seismicity, the seafloor bathymetry, and the stress transfer computation.…”

“…Thus, we kept fixed the parameters of one of the faults, adopting the values previously found with the one-fault solution, which had successfully modelled the displacement of Lefkada. The location and the strike of the second fault segment (F2, Figure 1b) was based on the relocated seismicity of Papadimitriou et al [21]. Moreover, topographic profiles along part of the F2 segment show that the fault passes by a bathymetric feature that could be related with tectonic activity.…”

“…We used the obtained source mechanisms ( Table 2) to investigate a potential stress interaction between F1 and F2 (with F2 as receiver fault). A similar scenario was previously examined [21], with a different fault configuration for the receiver fault, than the one we adopt. Here, based on our slip distributions, the static Coulomb stress changes ∆CFF, taking into account the pore pressure contribution, were estimated as [41]:…”

“…It is noteworthy that the recent (in 2003, 2014, and 2015) events that ruptured parts of the CTF, were all modelled as multiple source events, which indicates faulting complexity [13,19,20]. Papadimitriou et al [21], using high precision aftershocks of the 2015 sequence, proposed that the area has a network of fault segments, which in some cases are not clearly identified or easily distinguished. This complexity is also reflected in the modelling of geodetic data.…”