Climate warming in the Russian Arctic over the past 40 years shows a variety of patterns at different locations and time periods. In the second half of the 20th century, the maximum rates of warming were characteristic of the subarctic permafrost regions of Russia. But in the 21st century, the locations of the greatest rates of climate warming moved to the Arctic zone of Russia. It was one of the reasons for a sharp increase in permafrost temperatures, an increase in the depth of seasonal thaw, and the formation of closed taliks. It was found that as a result of climate change, the differences in permafrost temperatures between different cryogenic landscapes in the area of continuous and discontinuous permafrost distribution have decreased, and in the area of sporadic permafrost distribution are now practically absent. The thermal regime of the ground shows dramatic changes everywhere with a pronounced reduction in the depth of zero annual amplitude.

Most residential buildings and capital structures in the permafrost zone are constructed on the principle of maintaining the frozen state of the foundation soils. The changing climate and the increasing anthropogenic impact on the environment lead to changes in the boundaries of permafrost. These changes are especially relevant in the areas of piling foundations of residential buildings and other engineering structures located in the northern regions since they can lead to serious accidents caused by the degradation of permafrost and decrease the bearing capacity of the soil in such areas. Therefore, organization of temperature monitoring and forecasting of temperature changes in the soil under the buildings is an actual problem. To solve this problem, we use computer simulation methods of three-dimensional nonstationary thermal fields in the soil in combination with real-time monitoring of the temperature of the soil in thermometric wells. The developed approach is verified by using the temperature monitoring data for a specific residential building in the city of Salekhard. Comparison of the results of numerical calculations with experimental data showed good agreement. Using the developed computer software, nonstationary temperature fields under this building are obtained and, on this basis, the bearing capacities of all piles are calculated and a forecast of their changes in the future is given. To avoid decreasing the bearing capacity of piles it is necessary to prevent the degradation of permafrost and to supply the thermal stabilization of the soil. The proposed approach, based on a combination of the soil temperature monitoring and computer modeling methods, can be used to improve geotechnical monitoring methods.

Understanding the mechanisms responsible for the origin, evolution, and failure of pingos with explosive gas emissions and the formation of craters in the Arctic permafrost requires comprehensive studies in the context of fluid dynamic processes. Properly choosing modeling methods for the joint interpretation of geophysical results and analytical data on core samples from suitable sites are prerequisites for predicting pending pingo failure hazards. We suggest an optimal theoretically grounded workflow for such studies, in a site where pingo collapse induced gas blowout and crater formation in the Yamal Peninsula. The site was chosen with reference to the classification of periglacial landforms and their relation to the local deformation pattern, according to deciphered satellite images and reconnaissance geophysical surveys. The deciphered satellite images and combined geophysical data from the site reveal a pattern of periglacial landforms matching the structural framework with uplifted stable permafrost blocks (polygons) bounded by eroded fractured zones (lineaments). Greater percentages of landforms associated with permafrost degradation fall within the lineaments. Resistivity anomalies beneath pingo-like mounds presumably trace deeply rooted fluid conduits. This distribution can be explained in terms of fluid dynamics. N–E and W–E faults, and especially their junctions with N–W structures, are potentially the most widely open conduits for gas and water which migrate into shallow sediments in the modern stress field of N–S (or rather NEN) extension and cause a warming effect on permafrost. The results obtained with a new workflow and joint interpretation of remote sensing, geophysical, and analytical data from the site of explosive gas emission in the Yamal Peninsula confirm the advantages of the suggested approach and its applicability for future integrated fluid dynamics research.

We suggest new inversion techniques for IP-affected TDEM data. The method implies joint inversion of inductive and galvanic measurements, the galvanic array being configured in a way to separate the polarization and induction components of transient responses from a layered polarizable earth. The IP effects turned out to be reducible at a certain receiver configuration, which was predicted theoretically and proved valid in field tests.

The site where a peaceful underground nuclear explosion, Crystal, was detonated in 1974, at a depth of 98 m in perennially frozen Cambrian limestones, was studied by electrical resistivity tomography (ERT) in 2019. The purpose of our research, the results of which are presented in this article, was to assess the current permafrost state at the Crystal site and its surroundings by inversion and interpretation of electrical resistivity tomography (ERT) data. Inversion of the ERT data in Res2Dinv verified against ZondRes2D forward models yielded 2D inverted resistivity sections to a depth of 80 m. The ERT images revealed locally degrading permafrost at the Crystal site and its surroundings. The warming effect was caused by two main factors: (i) a damage zone of deformed rocks permeable to heat and fluids, with a radius of 160 m around the emplacement hole; (ii) the removal of natural land cover at the site in 2006. The artificial cover of rock from a nearby quarry, which was put up above the emplacement hole in order to prevent erosion and migration of radionuclides, is currently unfrozen.

The effect the metal casing of a vertical borehole may exert on transient electromagnetic (TEM) responses has been studied in a field experiment. Eddy currents in the casing affect transients only slightly at early times, but the casing effect predominates at late times. Therefore, early-time TEM response measured near a borehole can provide information on shallow subsurface. The late-time TEM signals induced by the eddy currents in the casing show exponential behavior b⋅ exp(–t/τ). The time constant τ refers to the rate of eddy current decay in the casing; the amplitude b is M12⋅ M23⋅ L–1⋅ τ–1, where L is the casing self-inductance, and M12 and M23 are the mutual inductances between the transmitter loop and the borehole and between the borehole and the receiver, respectively. Both M12 and M23 are controllable, while M23 is especially important for survey applications: by reducing it, one can reduce the casing effect on the TEM data. © 2014, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.