The Modern Active Tectonics of the Fergana Depression (Uzbekistan) Based on the Results of Tectonophysical Reconstruction of Crustal Stresses and Mathematical Modeling of the Velocity Field
Abstract
The seismotectonic process in the Fergana depression is caused by neotectonic activation of the earth’s crust. This process contributes to maintenance of the high seismic potential of the region, as evidenced by strong and destructive earthquakes, which took place here from ancient times until the present, and the preserved traces of paleoseismo-dislocation. Strong earthquakes are spatially and genetically connected with the areas of intense and differentiated movements in the latest and modern times, with the zones of active fractures in the earth’s crust. They participate in the formation of the neotectonic and modern structure and development of the relief of the Fergana depression. In tectonic zoning, instrumental data obtained by measuring the velocities of movement of geological structures are used. It is assumed that the nature of the movement determines the critical stresses, whose excess leads to the occurrence of earthquakes. At the same time, the results of modeling the stress state of the earth’s crust give a complex scenario, from which it is not always possible to isolate the main direction of forces. Moreover, various methods of modeling the stress–strain state of the earth’s crust give results that do not completely coincide. In this article, we compare the stress state of the earth’s crust and the displacement velocities obtained by numerically solving the equations of equilibrium of continuous media with the reconstructed stresses based on the mechanisms of the earthquake source for the Fergana depression.