Томография литосферы Азербайджанского региона на основе сейсмических шумов

Резюме

The aim of this study is to construct two-dimensional tomographic models of the structure of the Earthʼs crust and upper mantle of the Caucasus region using the dispersion characteristics of Rayleigh waves extracted from ambient seismic noise. The relevance of the work is due to the high seismic activity and geodynamic complexity of the Caucasus – one of the key links of the Alpine-Himalayan orogenic belt, where the ongoing interaction of lithospheric plates generates intense deformation processes. Seismic interferometry based on crosscorrelation of seismic noise records was used as the main method, which made it possible to restore Greenʼs functions and extract dispersion curves for subsequent inversion of group and phase velocities. The study covers the period from 2012 to 2024 and uses data from more than 70 seismic stations installed in Azerbaijan, Georgia and Turkey. As a result of seismic noise analysis, maps of Rayleigh wave group velocity variations at depths from 20 to 200 km were constructed, which made it possible to identify pronounced lithospheric heterogeneities of the Caucasus region. In the South Caspian Basin, the Kura and Alazani depressions, areas of reduced velocities were discovered, indicating the presence of thick sedimentary strata and a thermally weakened crust. Similar anomalies were found under large volcanoes (Elbrus, Kazbek, Ararat), interpreted as potential magmatic centers. High-velocity anomalies corresponding to a thickened, dense crust were recorded in the areas of the Lesser Caucasus and northern Iran, and at depths of 50–200 km – stable zones of the lithospheric mantle. In the eastern part of the Caucasus, signs of subduction processes are traced: deep-focus earthquakes and increased velocities in the mantle. Sharp contrasts are observed across the region’s mantle: from extremely low velocities in the west to extremely high velocities in the east and in the South Caspian zone.