Geological effects and tectonic environment of the 26 November 2019, Mw 6.4 Durres earthquake (Albania)

The Mw 6.4 26 November 2019, earthquake has been the strongest in the last decades in Albania, causing damages of intensity VIII to IX EMS in the epicentral region around Durres. The region north of Durres has experienced a maximum uplift of ca. 11 cm, based on SAR interferometry, which represents the main environmental effect induced by the earthquake. Other coseismic environmental effects were liquefaction mostly in the coastal area north and south of Durres, lateral spread in the Erzen river banks and possibly minor rock falls. As a whole, the observed effects are indicative of an intensity VIII to IX in the ESI scale. The rupture parameters that best fits the earthquake data (seismic moment, hypocentre depth, GPS data, deformation field from SAR interferometry), based on Coulomb modelling, show a reverse slip of 0.6 m on a NW-SE trending plane dipping 25o northeast, 20 km long and ca. 12 km wide, from 19.5 to ca. 15 km deep. The surface projection of the upper tip of the rupture is on the coast north of Durres. The inferred Coulomb stress change does not impose any significant load on the surrounding major faults, that is Kruja thrust, Lezha transfer fault, and the offshore thrust fault responsible for the 1979 Mw 7.1 Montenegro earthquake. The historical earthquakes and the regional tectonic setting, dominated by plate collision and important transfer fault zones suggest that the last earthquake might not be representative of the actual maximum seismic and surface faulting hazards in northwestern Albania, a region of fast industrial and touristic growth. This calls for detailed active tectonics studies with a palaeoseismological perspective in the region surrounding the epicentral area, where the two main towns in Albania lie.