Geodetic Source Modeling of the 2019 M w 6.3 Durrës, Albania, Earthquake: Partial Rupture of a Blind Reverse Fault

We address geometric and kinematic properties of the M w 6.3 26 November 2019 Durrës earthquake, the strongest earthquake in Albania in the past 40 years. Using coseismic surface displacements from Sentinel‐1 Differential Interferometric Synthetic Aperture Radar (DInSAR) and nearby Global Navigational Satellite System (GNSS) stations, we invert for the geometry and slip of the causative fault. We find that both a steep SW‐dipping fault (dip 71°) and a shallow NE‐dipping fault (dip 15°) can fit the data equally well. However, the slip on the SW‐dipping fault occurs at depths 11–23 km, similar to the depths of the mainshock and aftershock seismicity, and thus, we prefer that model. The location of our preferred fault plane correlates with the mapped SW‐dipping backthrust, the Vore fault. The fault rupture did not reach the surface, which implies that an updip stress propagation onto the unruptured shallow portion of the Vore fault and its secondary structures pose an increased seismic hazard for cities in Albania, including the capital, Tirana. The magnitude 6.3 earthquake near Durrës, Albania, on 26 November 2019 was the largest earthquake in the country for over 40 years. It caused 51 deaths and damaged over 2,000 buildings in Durrës and the capital city Tirana. The earthquake occurred below the surface, and it was not immediately clear in the aftermath which fault it occurred on. We investigated that question using a combination of satellite observation techniques: DInSAR (a radar method that maps movements of the ground in one dimension over the large area) and GNSS (observations of three‐dimensional movements of the ground at specific locations). Out of two possibilities, we prefer a model in which the earthquake occurred on a fault that steeply dips (tilts) to the southwest, between 11‐ and 23‐km depth, agreeing with the depths of the mainshock and aftershocks from seismology. This fault, the Vore fault, is partly mapped at the surface and runs close to Tirana. The upper 11 km of the Vore fault and its hanging wall structures did not move in this earthquake, and therefore, they could still sustain a damaging earthquake in the future, threatening Tirana and other cities in northwestern Albania. Geodetic source modeling of the M w 6.3 2019 Durrës earthquake is performed based on Sentinel‐1 DInSAR and GNSS observations A SW‐dipping fault‐plane agrees better with the seismic source parameters, depths, and locations of mainshock and aftershocks Rupture did