Active tectonic deformation and associated earthquakes: a case study—South West Carpathians Bend zone

Topo-Transylvania: a multidisciplinary Earth science initiative in Central Europe to tackle local and global challenges

“…This approach may provide a possible template for a similar investigation of the Transylvanian basin and clearly demonstrates the power, efficiency and limitation of numerical and physical modelling and inversion. Popa et al (2018) (in this issue) studied the focal mechanism of earthquakes occurring in the southwest Carpathian Bend area. The results implied the role of broader tectonic trigger mechanism for these regional earthquakes which challenges previous models and may contribute to the development of refined models for Vrancea earthquakes.…”

Strain partitioning during formation of oroclines and indentation

“…This means that 1 cm in our models corresponds to 7 km in nature, which yields a length-scale ratio L* = 1.43•10 -6 . With this length-scale ratio, 1.5 cm depth of the brittle-viscous transition in our models corresponds to ~10 km depth in nature, which is supported by the shallow seismicity and the crustal structure reported in the South and Serbian Carpathians (e.g., Dimitrijevic, 1994;Popa et al, 2018). Lithostatic stress at this depth in the experiments is 191 Pa, which corresponds to 280 MPa in nature, resulting in a stress-scale ratio of 6.82•10 -7 .…”

“…We choose the length scale ratio such that the brittle-viscous transition in the models is at a depth of ~10 km when scaled to nature. This depth of the brittle-viscous transition is consistent with a change in deformation behaviour of quartz-dominated lithologies from frictional sliding to creep (e.g., Kerrich et al, 1997;van der Pluijm and Marshak, 2004) for average continental geo-thermal gradients in the order of 30 °C/km (Turcotte and Schubert;Limberger et al, 2014Limberger et al, , 2018 and the depth extent of weak seismicity documented in the South-and Serbian Carpathians (e.g., Dimitrijevic, 1994;Popa et al, 2018). At this depth the vertical stress (i.e., lithostatic stress, σ = ρ•g•h, where ρ is quartz sand density, g is the gravitational acceleration and h is the thickness of the overlying sand layer) in the experiments is 220 Pa, corresponding to 280 MPa in nature, which results in a stressscale ratio of 7.87•10 -7 .…”

Identification of Antrophic Activity Interference in the Seismic Catalogue for Banat Region

“…Here we also considered other available information, such as the recording of earthquake sequences which are clearly identi ed. Thus, out of this data set, 122 events were identi ed by (Oros, 2012), (Popa et al, 2018), (Popa et al, 2019) as natural seismicity attributed to the 2014-2015 seismic sequence in Caras-Severin county, Băile Herculane-Mehadia sector and 2012-2018 Timișoara sequence.…”