The 26 November 2019 Mw 6.4 Albania Destructive Earthquake

Abstract

AbstractWith the strong 26 November 2019 earthquake that struck western Albania, several buildings collapsed, causing 51 casualties, mainly in the areas of Durrës and Thumanë. The destruction is attributed to several factors, including strong ground motion (maximum peak ground acceleration=192 cm/s2 in Durrës), soil liquefaction, site amplification, poor building workmanship and construction quality, aging of building materials, impact on buildings of the strong 21 September 2019 Mw 5.6 foreshock, and pre-existing stress on buildings sustaining differential displacements because of soft soil conditions in their foundations. In both areas, we estimated maximum seismic intensity of VIII–IX (modified Mercalli intensity and European Macroseismic Scale 1998 scales). Fault-plane solutions indicated reverse faulting striking northwest–southeast. From regional tectonics, we assumed that the causal fault dips to east-northeast, implying that the affected area is situated at the hanging wall domain of the causative fault. Using the Non-Linear Location program algorithm and ak135 velocity model and 71 P and S phases, we manually located the mainshock hypocenter offshore, at distance of ∼17 km from Durrës and at depth of ∼22 km. Adopting this solution, a finite-fault model of space–time seismic slip was developed from the inversion of teleseismic P waveforms. Strike 345°, dip 22°, rupture velocity 2.6 km/s, and total rupture duration ∼16 s fit the data. The rupture was complex, showing one main patch at the south and a second at the north with maximum slips of ∼1.5 and ∼1 m, respectively. The rake vector at the main slip area was 99°, indicating that the thrust-type component played the most important role in the rupture process. The total seismic moment released was estimated at Mo=5.0×1018 N·m corresponding to Mw 6.4.