Ground penetrating radar survey of thermocirque on a moraine in the Suntar River valley

The history of glaciation in the North-East of Russia is very poorly studied. In 2022, a thermocircus was discovered for the first time on moraine deposits in the Oymyakon Highlands. In the upper part of the moraine section, ice wedges were found which were not visible from the surface. To establish their size and configuration of the polygonal network, it was necessary to conduct geophysical studies, which were carried out using ground penetrating radar (GPR). Antennas with a central frequency of 150 and 50 MHz were used. The aim of the work was to survey the slope of the moraine adjacent to the thermocircus in the Suntar River valley using the GPR method. The parameters of the polygonal network were described, the applicability of the GPR method for such studies was assessed, and the methodology for taking measurements was developed. The main aims included localizing subsurface ice wedges, analyzing GPR data to identify features of the cryogenic structure, and developing recommendations for predicting thermokarst hazard. At the frozen soil and ice boundary, high-amplitude diffraction of electromagnetic waves is distinguished, which, according to the authors, is one of the attributes of localization of repeated ice wedges. Test measurements were carried out and a set of attributes for localization of underground ice wedges were determined depending on the antenna type. It is shown that the use of the GPR method allows localization of the polygonal-wedge ice system in moraine deposits.