Spatiotemporal Distribution of Strong Earthquakes and the Time Course of the Parameters of the Seismic Regime of the Bishkek Seismic Research Site of Kyrgyzstan

Abstract

This paper analyzes spatiotemporal distribution of strong historical earthquakes within the Bishkek seismic research (BSR) site. The main focus is on the spatial and temporal characteristics of crustal earthquakes in the instrumental period of observation, particularly the last 30 years (1991-2020). This period was the time of transition from the analog earthquake recording system to a digital one. Available epicenter maps of weak to moderate earthquakes were analyzed to identify areas of high and low seismic density. The analysis uses such parameters as the total number of earthquakes, magnitude, slope of the recurrence curve, and total seismic energy. The time course of seismic parameters was the main factor used to assess the current seismic setting of the Bishkek seismic research site. The slope of the earthquake recurrence curve was calculated using two methods: the least squares method and the maximum likelihood method. The analysis identified a downward trend showing a decrease in the number of earthquakes in the past 30 years (1991-2020). The results of this research can help develop a methodology for strong earthquake prediction and seismic hazard assessment of the BSR area.