Domino-style earthquakes along blind normal faults in Northern Thessaly (Greece): kinematic evidence from field observations, seismology, SAR interferometry and GNSS

Here we present a joint analysis of the geodetic, seismological and geological data of the March 2021 Northern Thessaly seismic sequence, that were gathered and processed as of April 30, 2021. First, we relocated seismicity data from regional and local networks and inferred the dip-direction (NE) and dip-angle (38°) of the March 3, 2021 rupture plane. Furthermore, we used ascending and descending SAR images acquired by the Sentinel-1 satellites to map the co-seismic displacement field. Our results indicate that the March 3, 2021 Mw=6.3 rupture occurred on a NE-dipping, 39° normal fault located between the villages Zarko (Trikala) and Damasi (Larissa). The event of March 4, 2021 occurred northwest of Damasi, along a fault oriented WNW-ESE and produced less deformation than the event of the previous day. The third event occurred on March 12, 2021 along a south-dipping normal fault. We computed 22 focal mechanisms of aftershocks with M≥4.0 using P-wave first motion polarities. Nearly all focal mechanisms exhibit normal kinematics or have a dominant normal dip-slip component. The use of InSAR was crucial to differentiate the ground deformation between the ruptures. The majority of deformation occurs in the vertical component, with a maximum of 0.39 m of subsidence over the Mw=6.3 rupture plane, south and west of Damasi. A total amount of 0.3 m horizontal displacement (E-W) was measured. We also used GNSS data (at 30-s sampling interval) from twelve permanent stations near the epicentres to obtain 3D seismic offsets of station positions. Only the first event produces significant displacement at the GNSS stations (as predicted by the fault models, themselves very well constrained by InSAR). We calculated several post-seismic interferograms, yet we have observed that there is almost no post-seismic deformation, except in the footwall area (Zarkos mountain). This post-seismic deformation is below the 7 mm level (quarter of a fringe) in the near field and below the 1 mm level at the GNSS sites. The cascading activation of the three events in a SE to NW direction points to a pattern of domino-style earthquakes, along neighbouring fault segments. The kinematics of the ruptures point to a counter-clockwise change in the extension direction of the upper crust (from NE-SW near Damasi to N-S towards northwest, near Verdikoussa)

Emerging patterns of resistance in a cohort of Greek patients with recurrent UTIs: a pilot study

Bacterial urogenital infections caused by multi-drug resistant organisms (MDROs), are increasingly becoming a severe public health issue. The purpose of the present study was to examine the epidemiology of recurrent UTIs along with antimicrobial resistance patterns in a cohort of patients followed as outpatients at an Infectious Disease clinic of a tertiary care center in Greece. One hundred, sequential patients suffering from recurrent UTIs and coming for clinical evaluation, follow-up and treatment were examined; microbiological urine culture results were analyzed. Patients were separated into Group A: patients with ≥3 urogenital infections during the last study year, and Group B: patients with ≤2 urogenital infections. Furthermore, antimicrobial resistance patterns and presence of MDROs in relation to the number of urogenital infections during a three years period was evaluated. Group A had a mean of 4.3 ± 1.7 urogenital infections during the last year of the study, while patients in Group B 1.9 ± 0.3 infections over a three years period. An age cut-off of 30 years was critical for higher UTI rates. Escherichia Coli was the predominant isolated pathogen in 96.2% of the patients. Patients with diabetes mellitus had a 3 fold-higher risk for ≥3 UTIs. Resistance to colistin and imipenem was associated with a history of more than 2 episodes of UTIs but observed in a small number of patients with comorbidities. In this pilot study MDRO detection in patients suffering from recurrent UTIs emphasizes the need for continuous epidemiological surveillance in order to improve our understanding of the evolution of resistance in a common community infection as well as to implement successful prevention strategies. © 2019, © 2019 Edizioni Scientifi che per l'Informazione su Farmaci e Terapia

Source Mechanism and Rupture Process of the 24 January 2020 Mw 6.7 Doğanyol–Sivrice Earthquake obtained from Seismological Waveform Analysis and Space Geodetic Observations on the East Anatolian Fault Zone (Turkey)

Here, we present the source mechanism and rupture process for the destructive 24 January 2020 Mw 6.7 Doğanyol–Sivrice earthquake at the East Anatolian Fault Zone (EAFZ, Turkey), obtained from seismological waveform analysis and space geodetic observations. Multi-data analyses and modelling in the present study provide fundamental data and strong constraints for retrieving complex source mechanism of an earthquake and its spatiotemporal slip characteristics along the ruptured segment of fault. The acquired slip model of this earthquake reveals heterogeneous slip distribution along strike N244°E of the fault plane dipping NW (68°) with duration of the source time function (STF) and low stress drop value (Δσ) of ~25 s and ~6 bars, respectively. Back-projection analysis validates fault length (L) stretching along strike for a distance of ~75 km and supports predominant south-westerly bilateral rupture propagation with a variable rupture velocity (Vr) of ~2.3–3.4 km/s along with two main patches, presumably a sequence of two asperities being ruptured following the surface trace of the EAFZ. The distribution of aftershocks based on the analysis of two months long data consistently confirms spreading of seismicity along the ruptured fault. The evaluation of Interferometric Synthetic Aperture Radar (InSAR) data reveals that left-lateral co-seismic slip and significant deformation extends for ~20 km on either side of the fault with evident post-seismic displacement. Yet, no significant vertical offsets were observed as GNSS stations detected only horizontal motions. Coda-wave analysis as an independent tool also confirms moment magnitude of Mw 6.7. Our results highlight a case of a damaging earthquake and enhance our understanding of earthquake mechanics, continental deformation and augmented earthquake risk on the EAFZ. © 2021 Elsevier B.V