Shallow Permafrost at the Crystal Site of Peaceful Underground Nuclear Explosion (Yakutia, Russia): Evidence from Electrical Resistivity Tomography

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.

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A review of open software resources in python for electrical resistivity modelling

Geoscience Letters ◽

10.1186/s40562-022-00214-1 ◽

2022 ◽

Vol 9 (1) ◽

Author(s):

Yonatan Garkebo Doyoro ◽

Ping-Yu Chang ◽

Jordi Mahardika Puntu ◽

Ding-Jiun Lin ◽

Tran Van Huu ◽

...

Keyword(s):

Electrical Resistivity ◽

Electrical Resistivity Tomography ◽

Geophysical Research ◽

Resistivity Tomography ◽

Subsurface Structures ◽

Data Inversion ◽

Scripting Language ◽

And Inversion ◽

Geoelectric Data ◽

Insight Into

AbstractGeophysical modelling performs to obtain subsurface structures in agreement with measured data. Freeware algorithms for geoelectrical data inversion have not been widely used in geophysical communities; however, different open-source modelling/inversion algorithms were developed in recent years. In this study, we review the structures and applications of openly Python-based inversion packages, such as pyGIMLi (Python Library for Inversion and Modelling in Geophysics), BERT (Boundless Electrical Resistivity Tomography), ResIPy (Resistivity and Induced Polarization with Python), pyres (Python wrapper for electrical resistivity modelling), and SimPEG (Simulation and Parameter Estimation in Geophysics). In addition, we examine the recovering ability of pyGIMLi, BERT, ResIPy, and SimPEG freeware through inversion of the same synthetic model forward responses. A versatile pyGIMLi freeware is highly suitable for various geophysical data inversion. The SimPEG framework is developed to allow the user to explore, experiment with, and iterate over multiple approaches to the inverse problem. In contrast, BERT, pyres, and ResIPy are exclusively designed for geoelectric data inversion. BERT and pyGIMLi codes can be easily modified for the intended applications. Both pyres and ResIPy use the same mesh designs and inversion algorithms, but pyres uses scripting language, while ResIPy uses a graphical user interface (GUI) that removes the need for text inputs. Our numerical modelling shows that all the tested inversion freeware could be effective for relatively larger targets. pyGIMLi and BERT could also obtain reasonable model resolutions and anomaly accuracies for small-sized subsurface structures. Based on the heterogeneous layered model and experimental target scenario results, the geoelectrical data inversion could be more effective in pyGIMLi, BERT, and SimPEG freeware packages. Moreover, this study can provide insight into implementing suitable inversion freeware for reproducible geophysical research, mainly for geoelectrical modelling.

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THE ELECTROTOMOGRAPHY SURVEY IN DIFFICULT GEOTECHNOGENIC CONDITIONS AT THE PEACEFUL UNDERGROUND NUCLEAR EXPLOSION "CRYSTAL" SITE

Interexpo GEO-Siberia ◽

10.33764/2618-981x-2021-2-3-61-68 ◽

2021 ◽

Vol 2 (3) ◽

pp. 61-68

Author(s):

Alexandr N. Shein ◽

Svetlana Yu. Artamonova ◽

Vladimir V. Potapov ◽

Nickolay O. Kozhevnikov ◽

Vladislav E. Ushnitskii

Keyword(s):

Electrical Resistivity ◽

Carbonate Rocks ◽

Nuclear Explosion ◽

Forward Modeling ◽

Measured Data ◽

Underground Nuclear Explosion ◽

Geological Environment ◽

Two Dimensional ◽

Data Inversion ◽

Significant Interference

The paper presents the results of measurements in 2019 by electrotomography at the site of the emplacement hole of the peaceful underground nuclear explosion "Crystal", carried in 1974 at a depth of 98 m in permafrost Cambrian carbonate rocks, and the neighboring forest area. The fence made of metal poles and barbed wire around the site, and the buried fragments of the casing of the emplacement hole create significant interference of measurements. To avoid the electromagnetic noise, the measured data of the apparent electrical resistivity was cleaned manually. Data inversion was performed in the Res2Dinv program. Geoelectric models, namely two-dimensional sections of the upper part of the geological environment to a depth of up to 80 m, were obtained. To verify the models, forward modeling was performed using the ZondRes2D program.

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