Analysis of Swarm Earthquakes on the Territory of the Elbrus Volcanic Center

Abstract

The paper presents the results of the analysis of swarm seismic events recorded in 2018 in the area of the Elbrus volcanic center by the North Caucasian seismological network of the FRC GS RAS. The standard method of station processing shows the hypocenters of recorded events in the area of the Elbrus volcanic center. The hypocenters of seismic events in swarm sequences were refined using the LOS software package, a complex combined location algorithm, methods of minimizing the time discrepancy in the source and grid search with depth enumeration. The described approach improves the reliability of location due to accounting for inaccuracies associated with incorrectly taken times of phase arrivals and minor deviations in travel times, depending on the velocity model of the medium used. According to the results of the study of the focal mechanisms of the strongest earthquakes, the type of movement was established, which is consistent with the kinematics of the Elbrus-Mineralnye Vody fault zone. Correlation analysis of the waveforms of the vertical component filtered in the frequency range of 1‒10 Hz, including P and S waves, for the nearest station shows a high coincidence of the analyzed data (correlation coefficient R ≥ 0.85), which indicates a high probability that events have similar sources and paths propagation of seismic waves. Comparison of the power spectral density of individual earthquakes in swarm sequences also demonstrates high similarity.