I. Kassaras

Source characteristics of the 2015 Mw6.5 Lefkada, Greece, strike‐slip earthquake

We present a kinematic slip model from the inversion of 1 Hz GPS, strong motion, and interferometric synthetic aperture radar (InSAR) data for the 2015 Mw6.5 Lefkada, Greece, earthquake. We will show that most of the slip during this event is updip of the hypocenter (10.7 km depth) with substantial slip (>0.5 m) between 5 km depth and the surface. The peak slip is ~1.6 m, and the inverted rake angles show predominantly strike-slip motion. Slip concentrates mostly to the south of the hypocenter, and the source time function indicates a total duration of ~17 s with peak moment rate at ~6 s. We will show that a 65° dipping geometry is the most plausible due to a lack of polarity reversals in the InSAR data and good agreement with Coulomb stress modeling, aftershock locations, and regional moment tensors. We also note that there was an ~20 cm peak-to-peak tsunami observed at one tide gauge station 300 km away from the earthquake. We will discuss tsunami modeling results and study the possible source of the amplitude discrepancy between the modeled and the observed data at far-field tide gauges.

Resolving the Tectonic Stress by the Inversion of Earthquake Focal Mechanisms. Application in the Region of Greece. A Tutorial

This work describes the derivation of the tectonic stress from the inversion of focal mechanisms of double-couple earthquakes. The presented material is based, in large part, on several review papers, lecture notes and practices on the matter, developed by the authors during the last years.

On the Lefkas (Ionian Sea) November 17, 2015 Mw=6.5 Earthquake Macroseismic Effects

ABSTRACT We exploit macroseismic observations and instrumental data aiming at explaining the effects of the 17th November 2015 Mw=6.5 earthquake, occurred beneath the southwestern peninsula of Lefkas Island (Ionian Sea) causing two casualties, major geo-environmental and slight-to-moderate structural effects. The spatial distribution of the structural damage of the local building stock is well correlated with the deformation pattern deduced from satellite geodesy, it appears though considerably low with respect to the ground deformation. Comparison with the previous strong earthquake on 14.8.2003 with Mw=6.2 occurred about 20 km to the north, shows that structural damage was significantly lower during the recent quake and also manifests good behaviour of the local buildings. This is partly explained by the characteristics of the ground motion and primarily explained by the unique concepts applied to the non-engineered buildings of Lefkas to resist ground motions.