Deep Earthquakes in the Caucasus: Recalculation Results

Abstract

The question of the existence of deep earthquake sources in the Caucasus is extremely important both for solving geodynamics problems, assessing seismic hazard, and seismic zoning of the region. It was previously believed that earthquakes with depths not exceeding 150 km can occur in the Caucasus. However, in recent years, this has become argumentative, reflected in a number of publications. This article shows that in the Caucasus, in addition to crustal earthquakes, rather deep mantle earthquakes also occur. This, in addition to direct determinations, is confirmed by data published in Caucasian earthquake catalogs and bulletins. The presence of deep earthquake sources in the Caucasus significantly changes our views on the regional structure and geotectonics. Obviously, crustal earthquakes dominate in the region’s seismicity, but it is clear that mantle earthquakes also make a significant contribution. The fact that they are fewer than crustal earthquakes in the total number may indicate that the crust is harder and more brittle than the upper mantle.
Keywords: earthquakes, hypocenters, catalogs, bulletins