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The results of experiments on electrical sounding of the near-surface layer of the Earth's crust in the fault zone, which have involved a recording of seismoacoustic and seismic noise in the close zone near the source (the primary dipole source), are represented. The experiments were carried out in 2021–2022 in the southern part of the Central Sakhalin fault with the use of the generator of electric pulses developed at IMGG FEB RAS, output electric power being up to 3 kW. The aim was to reveal seismoacoustic signatures of the medium reaction to the soundings with current pulses of 5–13 A. The generator provided significantly higher current in the dipole than its typical characteristics in the case of soundings for electrical exploration by resistance methods, as well as in the case of conventional seismic and electrical exploration. At the same time, the range of current amplitudes was much smaller in comparison with the case of a deep sounding based on application of geophysical MHD generators or other extra high-power electric pulses units. Up to now, the inverse seismoelectric effect has remained practically unexplored at currents in the “intermediate” range of ~10 A and scale lengths of the order of few hundreds of meters. The presence or absence of the medium reaction to electrical soundings was distinguished by the records of molecular-electronic sensors developed by R-sensors LLC: the CME-6111 broadband seismometer and the hydrophone, installed at a distance of about 50 m from one of the poles of the electric dipole source. An increase in the average level of seismoacoustic noise during electrical soundings was revealed, which is essentially a variety of the inverse seismoelectric effect of the second kind (excitation of elastic waves during an electric current run in a two-phase medium). Previously, no similar signature of medium reaction to the current pulses was noted in the close zone adjacent to one of the dipole electrodes. The noise level increase occurs almost without delay after the start of electrical soundings, and this is in accordance with the previously obtained results on the responses of seismic acoustic emission to powerful current pulses, which were used for a deep sounding in the Northern Tien Shan.

This article describes the process and results of the development and testing of a cost-effective, portable, safe to move by air geophysical pulse voltage generator for seismic exploration of the subsurface. The generator is based on high-speed power electronic keys of a new generation consisting of an insulated gate bipolar transistor or a field-effect transistor based on silicon carbide, a compact power converter of alternating voltage from an autonomous generator or electric network to direct voltage using pulse-width modulation and current or voltage stabilization depending on the mode set by a researcher. Field tests were conducted to confirm the suitability of the developed design of the generator and the correctness of the chosen parameters of its elements. To this end, a detailed analysis of the effect of the developed geophysical generator on the parameters of the geoenvironment was carried out.

Reliable short-term tsunami forecast on the Kuril Islands when earthquakes occur in the Kuril-Kamchatka Trench is the most difficult. Forecasting by the traditional magnitude method often leads to false tsunami alarms. Based on the examples of the events of 2006, 2007 and 2020 on the Kuril Islands, as well as the event of 2018 in Alaska, it was shown that according to the data of the ocean level measuring stations closest to the tsunami source (tsunami travel time is 10–20 minutes) it is possible to adequately predict the tsunami near the coast. Calculations of tsunami waveforms near the coast from data containing seismic noise have shown that the resulting waveforms contain high-frequency oscillations. However, these fluctuations do not interfere with the assessment of the real waveform and the danger of the expected tsunami. In contrast to forecast methods based on the magnitude criterion, the applied method of short-term tsunami forecast makes it possible to calculate the waveform: the amplitudes of the first, maximum waves, their arrival time at a given point and the estimated duration of the tsunami. The proposed method can become a tool that will improve the quality of operational tsunami warning, significantly reducing the number of false tsunami alarms.

Geophysical fields influenced by tectonics faults were observed, and instrumental observation results are analysed in the article. It is shown that fault zones are characterized by geophysical fields that are more variable than those in midmost segments of crustal blocks, more intense responses to weak external impacts such as lunar and solar tides and atmospheric pressure variations, and intensive relaxation. Transformation of energy between geophysical fields varying in origin takes place mainly in the fault zones.