Influence of local seismotectonic and engineering-geological conditions on seismic danger of territories (exemplified by a construction site in Uzhgorod city)

Objective. To identify the location of potentially active seismic zones in which local earthquakes may occur. To evaluate the predicted seismic shaking intensity (in MSK-64 scale points) considering impacts associated with the local tectonic and engineering-geological conditions of the study site. Methodology. The totality of data on the correlation between the length and magnitude of associated maximum energy earthquakes established seismotectonic potential of active or potentially seismoactive fault segments (lineaments) cut off by faults of the same or a lower order being transverse to their strike and located within the maximum possible vicinity to the studied site.  Quantitative assessment of the predicted seismic shaking intensity by seismological analogies for the territory was carried out in accordance with the norms regulated by DBN B.1.1-12-2014. Results. Based on the analysis of information on the geodynamic and seismotectonic situation in the vicinity of the projected structures site, we defined the location of potential seismic zones where local earthquakes may occur. The study determined seismotectonic potential of the closest to the site fault segments in terms of their maximum magnitudes which will not be exceeded for the next 50 years with a probability of 99%. Fault segments (1–5) marked on the tectonic map are located in a close proximity to the site. The greatest seismotectonic potentials Мmax = 4.32, Мmax = 4.03 are specific to faults 1 and 4 with lineament lengths L = ~18.91 km, L = ~13.23 km. Faults 2, 3, 5 demonstrate smaller values of seismotectonic potential Мmax = 3.42; 3.60; 3.48. It is known that earthquakes in the Transcarpathian trough are shallow, i.e. they occur at a depth of 2–5 km. Under these conditions, ІRM = 7.27, ІRM = 7.34 for faults 1 and 4 is the highest, the remaining faults 2, 3 and 5 have lower ІRM = 4.38; 5.49; 3.48 values per MSK-64 macroseismic scale and DSTU-B-V.1.1-28_2010 respectively. For the second category soils the evaluation is made in respect of their seismic properties. The maximum predicted impact of local potential earthquakes on the site area is established as IRM = 7.34 points per MSK-64 macroseismic scale and DSTU-B-V.1.1-28:2010. According to the data of engineering-geological surveys, within the limits of a 10-meter layer below a planning mark, the soils of site allocated engineering-geological area are specific for the 2nd category per their seismic properties. The object of reconstruction falls in CC3 class of consequences (responsibility). According to ZSR-2004–C map, the standard (background or input) intensity of seismic shaking within the site is IN = 8 points per the MSK-64 scale. Scientific novelty. Seismic faults within the vicinity of Uzhgorod city were determined; seismotectonic potential and maximum possible impact of local earthquakes on the site territory and designed structures stability was established. Practical relevance. The construction site SMZ gives specified values of seismic impacts in relation to the general seismic zoning of the country. This allows considering possible increase in seismic magnitude at the stage of seismic resistant construction design. Taking into account SMZ results at construction of engineering structures allows avoiding human casualties and reducing economic losses at seismic manifestations.