Crustal Strains in the Ossetian Region of the Greater Caucasus Based on GNSS Measurements

— Based on long-term observations over the Ossetian regional GNSS network, which currently consists of 59 compaign sites and 7 stations, estimates of the strain rate and spatial distribution in the Ossetian part of the Greater Caucasus are obtained. The primary data analysis involves constraining the coordinates of the monitoring GNSS compaign sites by combining the regional network solution with the global solution calculated in global data centers. As many as 45 IGS stations included into the International Terrestrial Reference Frame (ITRF) are selected as fiducial stations. The strain-rate tensor is calculated using the Shen method. To interpret the geodynamic settings, information on regional seismicity acquired from the Earthquakes of Russia database of the Federal Research Center Geophysical Survey, Russian Academy of Sciences (RAS), is used. The results show that, in general, the Ossetian region is in the state of tectonic compression on top of which several characteristics of particular structures of the region are revealed. The Main Caucasian Ridge and the deflection of the southern slope are in the state of not only submeridional compression, but also sublatitudinal extension, which leads to an intense dilatant expansion of the eastern segment of this area. The strain pattern of the northern part of the Ossetian region differs from the southern one. The northern slope of the Main Caucasian Ridge zone and the foothill trough, including the Vladikavkaz Fault Zone, are in the state of compression with moderate intensity. At the same time, an analysis of the distribution of earthquake epicenters has shown that the Northern Branch is currently aseismic in the central and eastern parts of the Vladikavkaz fault. This geodynamic feature indicates the high seismic potential of the Vladikavkaz Fault Zone.