SIGNS OF AN UPCOMING SEISMIC EVENT ON THE BISHKEK GEODYNAMIC TEST AREA ACCORDING TO THE TRANSIENT ELECTROMAGNETIC MONITORING DATA

The RAS Research Station conducts geodynamic research on the Bishkek geodynamic test area (BGTA) using on-power time-lapse measurements of an unsteady electromagnetic field produced by a grounded electrical line. In order to relate the electromagnetic monitoring signals to the recorded seismic events, the authors proposed the following characteristics (indicators): a) time of arrival of a maximum value signal at the observation point; b) voltage-time characteristics of the pulse; c) confidence interval for the average daily values of a signal. The sensitivity of these indicators to seismic events was illustrated by the example of a swarm of seismic events (K>8) recorded near the village of Kegety at the BGTA in April 2017. It has been found that, in the period of April 1–17, 2017, the time series of the three indicators contained no temporally synchronized anomalies. However, on April 18–20, 2017, all indicators showed the distinct temporally synchronized anomalies, which can be considered as precursors of the Kegety earthquake swarm whose main shock was recorded on April 21, 2017. The paper substantiates the possibility of using the above-mentioned indicators for medium-term prediction of seismic events. In order to automate the processing of the time series, it is proposed to create a digital platform to analyze a long-term array of electromagnetic monitoring data from all observation points. This paper starts a series of publications on the diffusion kinematics of non-stationary sounding in relation to the problems of electromagnetic monitoring of seismotectonic processes.