Spatial Distribution of Crustal Earthquakes in the Caucasus

Abstract

Previous results on the location of crustal earthquake foci in the Caucasus clearly show that the methods used in seismic service practice to determine the hypocenters of earthquakes do not allow accurate localization of events and can hardly be used to forecast earthquakes or study the structure of the Earth’s crust and upper mantle in detail. The arrival times of seismic waves often have large errors that prevent qualitative processing of observations and, therefore, is is difficult to obtain reliable results. In addition, the use of only one velocity curve or one set of travel-time curves for all stations of the network hinders accurate determination of the location of earthquake hypocenters. In order to localize earthquake foci with high precision, it is also necessary to have a sufficiently detailed representation of the structure of the Earth’s crust and upper mantle in the studied region. It is also desirable to take information about the structure of the region not from earthquake data, but based on other observations, e.g., deep seismic sounding (DSS) data. Using seismological bulletins for 1970–2015, we have redetermined the hypocentral coordinates of crustal earthquakes in the Caucasus. The new distribution of crustal earthquake hypocenters in the Caucasus differs significantly from the old distribution obtained from the catalog. This may become the basis for refining ideas about the regional geodynamics.