Seismogenic fault system of the M-w 6.4 November 2019 Albania earthquake: new insights into the structural architecture and active tectonic setting of the outer Albanides

A seismic sequence that affected the Durres region in late 2019 to early 2020 sheds new light on the structural architecture and active tectonic setting of the northern outer Albanides. Stress inversion analysis using focal mechanisms confirms that the area is dominated by ENE-trending horizontal maximum compression. The seismogenic sources consist mainly of ENE-dipping thrust faults roughly parallel to the coastline. The hypocentre distribution indicates that most of the earthquakes, including the M-w 6.4 main shock, nucleated within the basement, with only some of the shallow aftershocks tending to cluster around the deeper portion of previously identified seismogenic structures within the sedimentary cover. Our results, unravelling for the first time the fundamental role of deeply rooted, crustal ramp-dominated thrusting in seismogenesis, imply a profound reconsideration of the seismotectonic setting of the region in terms of a correct assessment of seismic hazard in this densely populated area of Albania.

Automated summary

The seismic sequence in the Durres region from late 2019 to early 2020 showed that the area is dominated by ENE-trending horizontal maximum compression with seismogenic sources mainly consisting of ENE-dipping thrust faults. Most earthquakes, including the main shock, originated within the basement, while shallow aftershocks tended to cluster around previously identified seismogenic structures within the sedimentary cover. These findings indicate a profound reconsideration of the seismotectonic setting in the region and the assessment of seismic hazard in densely populated areas of Albania.