The results of experimental studies of electric field disturbances generated by sources of an ionospheric origin in the coastal zones of the White and Barents seas are presented. The data recording was performed by geophysical stations GI-MTS-1. The horizontal electric field was recorded by telluric lines 50 m long. The Ex component was set orthogonally to the coastline in the direction from the shore, and the Еy component was directed along the coastline. In the coastal strip of the sea–land contact, a zone of anomalous increase in the amplitude of ULF variations (F < 1 Hz) of the Ex component adjacent to the water’s edge was revealed. An additional narrow zone of anomalous amplification of the ULF variations of the electric field is observed at a distance of 30 m from the water’s edge. The coastal effect reaches its maximum near the water’s edge in the coastal zone and decreases with distance from the seashore.

Представлены результаты экспериментальных исследований возмущений электрического поля, созданных источниками ионосферного происхождения в прибрежных зонах Белого и Баренцева морей. Регистрация данных выполнялась геофизическими станциями GI-MTS-1. Горизонтальное электрическое поле регистрировалось теллурическими линиями длиной ~50 м. Ех компонента напряженности электрического поля устанавливалась ортогонально береговой линии в направлении от берега, компонента Еу - вдоль береговой линии. В прибрежной полосе контакта море-суша выявлена зона аномального увеличения амплитуды в полной и переменной Ех компоненты, примыкающая к кромке воды (береговой эффект). На расстоянии ~ 30 м от кромки воды наблюдается дополнительная узкая зона аномального усиления величины УНЧ-вариаций электрического поля, связанная с локальной геоэлектрической аномалией. Максимальный береговой эффект наблюдается возле кромки воды в береговой зоне и уменьшается с удалением от берега моря.

The possibility of detecting deep polarized objects in natural electromagnetic fields is shown experimentally on the basis of synchronous measurements of the vertical component of long-period variations in the magnetic field of the Earth. Interpretation of the data of induced polarization is performed using the method of analytical continuation of geophysical fields downwards (towards the sources).

This article is devoted to describing the theory, technique, and first experimental results of a control source electromagnetic (CSEM) study of the Earth’s crust and ionosphere with the use of two mutually orthogonal industrial transmission lines 109 and 120 km in length in the frame of FENICS (Fennoscandian Electrical Conductivity from Natural and Induction Control Source Soundings) experiment. The main part of the measurements is executed on the territory of the Fennoscandian shield at distances from the first hundreds kilometers up to 856 km from the source with the purpose of the deep electromagnetic sounding of the Earth’s crust and upper mantle. According to the results of these studies clarifying the parameters of “normal” (standard) geoelectric section of the lithosphere to a depth of 60–70 km, the anisotropy parameters are evaluated and a geothermal and rheological interpretation in conjunction with the analysis of the seismic data is executed. Furthermore, to study the propagation of ELF–LLF waves (0.1–200 Hz) in an “Earth–Ionosphere” waveguide, the measurements are carried out apart from Fennoscandian shield at distances up to 5600 km from the source (in Ukraine, Spitsbergen, Poland, Kamchatka, and other areas). According to the results of these studies, the experimental estimates of the influence of the ionosphere and of the displacement currents on the propagation of ELF–ULF waves in the upper half-space at the different azimuths generation of the primary field are obtained.

Electromagnetic soundings with the fields of natural (magnetotelluric (MT), and audio magnetotelluric (AMT)) and high-power controlled sources have been carried out in the region of the SG-6 (Tyumen) and SG-7 (En-Yakhin) superdeep boreholes in the Yamal-Nenets autonomous district (YaNAD). In the controlled-source soundings, the electromagnetic field was generated by the VL Urengoi-Pangody 220-kV industrial power transmission line (PTL), which has a length of 114 km, and ultralow-frequency (ULF) Zevs radiating antenna located at a distance of 2000 km from the signal recording sites. In the soundings with the Urengoi-Pangody PTL, the Energiya-2 generator capable of supplying up to 200 kW of power and Energiya-3 portable generator with a power of 2 kW were used as the sources. These generators were designed and manufactured at the Kola Science Center of the Russian Academy of Sciences. The soundings with the Energiya-2 generator were conducted in the frequency range from 0.38 to 175 Hz. The external generator was connected to the PTL in upon the agreement with the Yamal-Nenets Enterprise of Main Electric Networks, a branch of OAO FSK ES of Western Siberia. The connection was carried out by the wire-ground scheme during the routine maintenance of PTL in the nighttime. The highest-quality signals were recorded in the region of the SG-7 (En-Yakhin) superdeep borehole, where the industrial noise is lowest. The results of the inversion of the soundings with PTL and Zevs ULF transmitter completely agree with each other and with the data of electric logging. The MT-AMT data provide additional information about the deep structure of the region in the low-frequency range (below 1Hz). It is established that the section of SG-6 and SG-7 boreholes contains conductive layers in the depth intervals from 0.15 to 0.3 km and from 1 to 1.5 km. These layers are associated with the variations in the lithological composition, porosity, and fluid saturation of the rocks. The top of the poorly conductive Permian-Triassic complex is identified at a depth of about 7 km. On the basis of the MT data in the lowest frequency band (hourly and longer periods) with the observations at the Novosibirsk observatory taken into account, the distribution of electric resistivity up to a depth of 800 km is reconstructed. This distribution can be used as additional information when calculating the temperature and rheology of the lithosphere and upper mantle in West Siberia. The results of our studies demonstrate the high potential of the complex electromagnetic soundings with natural and controlled sources in the study of deep structure of the lithosphere and tracing deep oil-and-gas-bearing horizons in the sedimentary cover of the West Siberian Platform within the Yamal-Nenets autonomous district.