AN ESTIMATE OF THE POSSIBLE IMPACT OF AN EXPERIMENTAL ELECTRIC PULSE SOURCE ON SEISMIC AND SEISMOACOUSTIC NOISE IN THE CENTRAL SAKHALIN FAULT ZONE

The paper presents the results of shallow-depth electrical sounding carried out in 2021–2022 near the Central Sakhalin fault at the geophysical test site of the IMGG FEB RAS (Petropavlovskoye village, Aniva district). Electrical soundings were carried out using a pulse voltage generator developed at the IMGG FEB RAS. The aim of the experiment was to evaluate the response of the medium in the near-fault zone to the impact of current pulses, the amplitude of which is significantly greater than that for resistivity prospecting or seismoelectric prospecting methods but many times less than that for high-power electrical sounding in Central Asia with the aid of geophysical MHD generators or electric pulse installations. The response of the medium was determined based on the records obtained from the seismic instruments located at the Petropavlovskoye test site – a broadband seismometer CME-6111, molecular-electron hydrophone, – as well as on the records of seismic noise at the "Ozhidayevo" and "Kholmsk" stations of the of the SB FRS GS RAS and on short-period seismometers Zetlab 7152-N and SPV-3K installed near the temporary sites in the test area. The results of processing of the seismoacoustic data obtained by a hydrophone for four experimental stages (13 days of serial sounding using unipolar current pulses) showed an increase in the noise amplitude in the near-surface layer during electrical soundings in the Central Sakhalin fault zone. This may indicate the influence of electrical soundings on the sources of seismoacoustic signals, i.e. on the medium destruction at the electrical impact site. Waveform recordings from all seismometers revealed the changes in seismic noise levels that correlate with the passage of cyclones causing high wind loads and changes in atmospheric pressure. Autumn-spring cyclones, frequent in Sakhalin, occurred at all stages of the experiment, which is why responses to electrical impact in seismic noise could only be recorded by the CME-6111 seismometer, located near the sounding source. This research determined the direction for improving electric current sources, increasing their power for shallow and deep sounding of the earth’s crust.