Basis of seismic microundation for Syktyvkar

Despite the relatively weak seismicity of the Komi Republic, its southern part, including Syktyvkar, is referred to a six-point seismic zone on a map of general seismic zoning (GSZ-97 C). It is historically known that in 1939 a seven-point earthquake occurred in the junction zone of the Sysolsky arch and the Kirov-Kazhim aulakogen, which was called the Sysolsky earthquake. This gives us the right to assert that in the future a similar seismic event can be repeated. The greatest number of earthquakes occurred in the Kirov-Kazhim seismogenic zone, which is confirmed by instrumental records of seismograms. An important point is that within the city of Syktyvkar there is a large industrial wood chemical plant, which, according to the status of environmental hazard, belongs to the most critical objects (EIO). Therefore, ensuring the safety of the operation of this enterprise requires detailed seismic zoning (DSZ) and microseismic zoning (SMZ), which can determine the parameters of the ultimate seismic effect on the underlying geological section. In accordance with this, we adhered to the following algorithm for solving the problems posed: - a two-level assessment of the seismic effects of the maximum estimated earthquake (MEE), which may exceed the estimated seismic hazard of 0.5 % for 50 years and a projected earthquake (DE), where the probability of exceeding the estimated seismic hazard can reach 1 % for 50 years (scale 1 : 2 500 000 - 1 : 1 000 000); - the set of probabilistic expected seismic impacts on the most important national economic objects was determined (scale 1 : 500 000 - 1 : 200 000); - Quantitative assessment of the effect of engineering-geological conditions on the initial seismicity was carried out (scale 1 : 25 000 - 1: 5 000). Thus, the main goal of this work is to obtain initial parameters corresponding to strong soil motions for the most unfavorable conditions, when rocky soils are covered by thick Quaternary deposits of the second and third (fourth) soil categories.