ON THE GEOMAGNETIC FIELD VARIATIONS ASSOCIATED WITH AFTESHOCK-SEQUENCED EARTHQUAKES

This article provides examples of aftershock sequences in the context of time series of the geomagnetic field variations ΔТ for the 2003–2007 period when the Bishkek geodynamic polygon area experienced an increase in seismic activity. These examples are supplemented with an analysis of a series of the 2017 Kegety earthquakes accompanied by a large number of aftershocks; besides, an attempt has been made to analyze the impact of the January 22, 2024 Uqturpan earthquake, China, – the last major M7.0 event, – on the geomagnetic situation within the monitoring network. Changes in the stress-strain state of the geoenvironment associated with the generation and occurrence of earthquakes are recorded in the form of abnormal variations of the geomagnetic field due to the use of high-precision magnetovariation stations operating at the observation locations RS RAS. A relationship has been found between the ΔT variations and the impending earthquake by comparing the magnetometric data with the catalog data from the KNET seismological network. The stationary sites monitored ΔТ variations during seismic events with different energy classes K and, if the earthquakes of energy class K=6–8 (weak) are visible on the ΔТ graphs just sometimes against a continuous background, then the events with K≥10, especially those accompanied by a large number of aftershocks, are seen thereon as well-defined ΔТ anomalies. It seems promising to conduct this kind of research for other earthquakes in order to study the influence of seismic events on variations of the geomagnetic field.

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