DISCHARGE OF SEISMOTTONTONIC VOLTAGES IN THE FOCAL ZONES OF STRONG EARTHQUAKES OF THE CENTRAL PART OF THE GREAT CAUCASUS

Abstract

Aftershock process spatio-temporal-energy distribution analysis was made on Racha (29.04.1991 M = 7,0), Barisaho (23.10.1992 M = 6,5), Zakatala (07.05.2012 M = 5,6) earthquakes occurred on the southern slope of the central part of the Greater Caucasus. On the identified focal areas on the basis of quantitative estimates of the relative deformation characteristic regularities and features of seismotectonic stress release are identified. At the first stage, an analysis of the spatial distribution of aftershocks was carried out. Applying the modern software package GIS, maps of aftershock areas of these earthquakes are constructed and their area values are estimated. At the second stage, a temporary analysis of aftershock processes was performed. For this purpose, the attenuation of the intensity of the aftershock process in time was studied. In order to study the discharge of seismotectonic stresses, Benyoff's graph, which characterizes the release of the energy of seismotectonic deformations, was widely used in seismological practice. Discharge of seismotectonic stresses in the focal zones of the Rachin and Barisakh earthquakes has a steep decline. On the graph of the Zakatala earthquake three stages are visually observed. These features are associated with the lithological composition and stratigraphic features of the geological environments of the focal zones of these earthquakes. In the area of the young mountain-fold structure of the Greater Caucasus, seismotectonic stresses are depleted more intensively and in a relatively short time interval, and in the Transcaucasian Late Alpine intermountain molasses trough this process has a protracted character.