Ground Deformation and Seismic Fault Model of the M6.4 Durres (Albania) Nov. 26, 2019 Earthquake, Based on GNSS/INSAR Observations

Abstract

We identify the source of the Mw = 6.4 earthquake that rocked north-central Albania on November 26, 2019 02:54 UTC. We use synthetic aperture radar interferograms tied to the time series of coordinates of two permanent Global Navigation Satellite System (GNSS) stations (DUR2 and TIR2). We model the source by inverting the displacement data. Assuming in our model a half-space elastic medium and uniform slip along a rectangular fault surface, we invert the 104 picked measurements on a couple of ascending and descending interferograms to calculate the parameters of the fault. All inversions made with different input parameters converge towards a stable and robust solution with root mean square (r.m.s.) residual of 5.4 mm, thus ~1/5 of a fringe. They reveal that the earthquake occurred deep in the crust on a low-angle fault (23°) dipping towards east with a centroid at 16.5 km depth. The best-fitting length and width of the fault are 22 and 13 km, and the reverse slip, 0.55 m. The seismic moment deduced from our model agrees with those of the published seismic moment tensors. This geometry is compatible with a blind thrust fault that may root on the main basal thrust, i.e., along the thrust front that separates Adria–Apulia from Eurasia. It is notable that there is a 123 ns yr−1 active shortening of the crust between the GNSS stations DUR2-TIR2 (equivalent to a shortening rate of 3.6 mm yr−1), and roughly in the east–west direction. Given this amount of strain the recurrence time of M6+ earthquakes along this fault should be of the order of 150 years.

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

“…We could not unambiguously find a preferred optimal rupture plane just based on the geodetic data-to-model misfit, as 10.1029/2020GL088990 models for both fault planes fit the data equally well (misfit < 1 cm). Caporali et al (2020), Ganas et al (2020), and Papadopoulos et al (2020) propose and model only the NE-dipping fault as a causative fault primarily based on the interpretation of the regional structural settings. A similar mechanism for the NE-dipping fault is presented but with different centroid depths and coseismic slip values, mostly due to an applied inversion method with certain assumptions (Table S7).…”

Destructive M6.2 Petrinja Earthquake (Croatia) in 2020—Preliminary Multidisciplinary Research

“…The M5.3 earthquake that struck the capital city of Zagreb and its surroundings on 22 March 2020 [51] caused Grade 4 (DG 4) to Grade 5 (DG 5) damage to the old city centre threeto five-storey unreinforced masonry buildings, which dated from the Austro-Hungarian monarchy to 1920 (vulnerability class B [43]). The prevalence of Grade 4 (DG 4) to Grade (DG 5) damage to vulnerability class B buildings was also evident in the aftermath of the M6.4 2019 Durrës, Albania earthquake, which had a PGA value of 0.19 g [52]. However, buildings that were built in compliance with contemporary codes such as masonry infilled RC frames (vulnerability classes C and D [43]) experienced Grade 1 (DG 1) and Grade 2 (DG 2) damage to RC frame structures but not Grade 4 (DG 4) or Grade 5 (DG 5) damage, namely very heavy damage or collapse, respectively, of masonry infill walls (prevailing out-of-plane damage).…”

Review of Works Combining GNSS and InSAR in Europe

“…Furthermore, Zoran [154] combined geospatial information, i.e., GPS and SAR images, with in situ information to assess the seismic hazard associated with the Vrancea area in Romania. Other interesting research in the field of tectonism utilized earthquake observations with remote sensing data from the M w 6.4 Durres (Albania) earthquake that occurred in 2019 [155] and the M w 6.5 Lorca earthquake (Spain) [56]. Studies on seismic [156] and crustal deformation [157], sometimes connected to strain rate analysis [66], or interactions with volcanic systems [68,69], connected to earthquake seismic swarms or active tectonic faults, are more common.…”