Regional seismotectonics of focal zones of the east Turkey earthquakes on 06 February 2023 and geodynamic model of the source of the strongest earthquake (Mw =7.8)

Abstract

Relevance. The complex structure of interaction of major macro and mezoplates is presented in the paper. The mobile Arabian Plate under the influence of near-meridional tectonic stresses, with an average speed of 30 mm∙year-1, wedges into the orogenic structures of the Lesser and Greater Caucasus, pushing the Anatolian and Black Sea mezoplates to the west along the flanks, and the South Caspian and Iranian mezoplates to the east. Methodology. Based on the analysis of the spatial distribution of focal zones of strongest earthquakes of the region with М≥6.7 for the period 1900 to present days, their confinement to the main deep faults is shown. The focal zones of first two strongest earthquakes of 06 February 2023 with Mw=7.8 and Mw=7.5 are located on the East Anatolian Fault, near the cities of Gaziantep and Karamanmarash, etc. Results. Based on the analysis of parameters of focal mechanisms of the earthquakes 06 February 2023 a version has been put forward that these are “doublet” earthquakes that served as a trigger mechanism for the occurrence of the earthquake of 06 February 2023 with Mw=6.3. The analysis of instrumental data from the Gaziantep (Turkey) earthquake with Mw=7.8 made it possible to determine the parameters and spectral characteristics of the focal zone radiation. It has been determined, that the main rupture is a complex non-linear process of rupture propagation and involves 4 sub focal zones. The geodynamic model of the earthquake helped in identifying the main patterns and characteristic features of the rupture formation of sources and to assess the overall picture of seismogenesis.