Summary The 2019 Mw 6.4 Durrës earthquake in Albania caused severe loss of life and economic damage, highlighting the seismic hazard along the Adriatic–European plate boundary. This study provides the first high-resolution analysis of the aftershock sequence based on data from a dense local seismic network deployed three weeks after the mainshock. Using machine-learning detection and phase-picking tools, we identified 19 152 aftershocks (Ml − 1.8 to 4.6; Mc ≈ 1) over a nine-month period. Based on a newly derived 1D velocity model with station corrections, accounting for large vertical and lateral velocity variations, we relocated the events applying cross-correlation based differential travel times and the double-difference algorithm. The refined seismicity images clearly reveal several sub-parallel ∼30° NE-dipping blind fault structures; the most prominent one, between 12 and 18 km depth, probably hosted the Durrës mainshock. The blind thrust faults lie beneath thick sediments and cut through a carbonate platform and into the Adriatic basement, indicating thick-skinned deformation. Our observations may be interpreted as incipient large-scale slicing and underplating of subducted Adriatic crust. Additional shallow seismicity within a duplex structure in the hanging wall points is relevant for seismic hazard, as even a relatively moderate earthquake occurring close to the surface could cause significant damage.
Heiden et al. (Thu,) studied this question.