Arctic Marine Electromagnetic Sounding

Marine geoelectromagnetic soundings with artificial sources is strongly hampered by the influence of a conductive layer of seawater. It is known, in practice, only one broad, successful application of electrical exploration – in the form of CSEM. However, the method has annoying limitations-the need to dive the installation to the bottom of the deep (more than 1000 m) sea and huge distances (up to 15 km). In the sea, covered with ice, and this method is not applicable. The possibility of deep sounding from the sea surface, and, therefore, from the ice surface arises if you use the TM-polarization field. Such a field in its pure form is generated by a vertical electric line (VEL) or a circular electric dipole (CED). VEL has known drawbacks even when used at sea. At the same time, the efficiency of CED is preserved in one-dimensional and three-dimensional situations, in frequency and time mode. Moreover, with the help of three-dimensional mathematical modeling, we show that the installation of CED is most effective on the sea surface. Thus, for electromagnetic sounding from the ice surface in the Arctic, under the condition of long-term ice drift, the use of CED is optimal and, in fact, there is no alternative. The experience of the NP stations showed that during the drift the station goes a long way in the Arctic regions, where information about the geology of the bottom is extremely scarce. Nowadays, it is planned to organize new drifting stations on the basis of ice-resistant self-propelled platform (LSP), which gives the prospect of geophysical research in the Arctic, including electromagnetic sensing, a new reality. In addition to general questions, the paper develops a three-dimensional mathematical apparatus for the established CED field in the born approximation, which is quite adequate in the conditions of the conducting section, in the presence of deep local inhomogeneities, and also considers the results of experiments with the installation of CED on the ice of the Ob reservoir.