The source parameters of earthquakes of Bishkek geodynamic proving ground (Northern Tien Shan)

Abstract

Based on the method of polarity of signs of P-waves, the focal mechanisms of 1674 earthquakes with M ≥ 1.6, which occurred on the territory of the Bishkek geodynamic proving ground (BGPG) from 1994 to 2020, were determined. Some characteristics of the complete catalogue are presented. Quantitative distributions by the type of mechanisms and diagrams of azimuths of the main stress axes are constructed. A variety of focal mechanism of earthquake is observed, most of them are reverse fault, oblique reverse fault, and horizontal strike-slip fault. The compression axis for most of the events has a north-northwest direction and a sub-horizontal position. For 183, dynamic parameters (DP, source parameters) were obtained: spectral density Ω0, corner frequency f0, scalar seismic moment M0, source radius (Brune radius) r, and stress drop Δσ. The correlations between DP and energy characteristic (magnitude) and scalar seismic moment are investigated. The smallest correlation coefficient was obtained for stress drop.