100 Years of Paper Seismograms from Denmark and Greenland, 1907–2008

The paper seismograms from 100 years of observations in Denmark and Greenland has since October 2021 been made available through the Danish National Archives. Five case stories illustrate the quality and variation of the seismograms, and the historical context of operation of the stations. (1) The earliest recorded earthquake in the archive is recorded at GDH station in Greenland, where the 1907 Mw 7.2 earthquake in Tajikistan is recorded on smoked paper. (2) The first Danish earthquake is a local event close to Copenhagen in 1930. (3) We have illustrated the 50 megaton nuclear explosion in Novaya Zemlya in 1961—the largest nuclear test explosion ever. (4) The M 9.2 earthquake in Alaska in 1964 recorded on several instruments at COP. (5) A local earthquake in northeast Greenland recorded both on paper on World-Wide Standard Seismographic Network instruments and digitally on a modern broadband instrument.

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.

Numerical modeling of strong effects on ionospheric plasma

В работе представлены постановка задачи начальной стадии мощного антропогенного возмущения ионосферы для последующего вычисления высотно-временного распределения ионосферно-магнитосферных параметров. Данная задача имеет огромное значение в плане теоретического исследования таких возмущений на математических моделях изучаемой среды. Такие возмущения сопровождаются различными физико-химическими процессами, которые к настоящему времени плохо изучены. Основным источником сильных возмущений ионосферы являются мощные электромагнитные излучения (сильная солнечная вспышка, мощный ядерный взрыв). Такие электромагнитные возмущения могут вызывать сильнейшие глобальные перераспределение всей атмосферы Земли, которые к настоящему времени недостаточно надежно изучены, и одним из способов их изучения, является математическое моделирование. Приводится результаты вычислительного эксперимента начальной стадии ионизации нейтрального газа, которые могут помочь в дальнейшем исследовании такого процесса. The paper presents the formulation of the problem of the initial stage of a powerful anthropogenic disturbance of the ionosphere for the subsequent calculation of the altitude-time distribution of the ionosphere-magnetospheric parameters. This problem is of great importance in terms of the theoretical study of such perturbations on mathematical models of the studied environment. Such disturbances are accompanied by various physicochemical processes, which are poorly understood by now. The main source of strong disturbances in the ionosphere are powerful electromagnetic radiation (strong solar flare, powerful nuclear explosion). Such electromagnetic disturbances can cause the strongest global redistribution of the entire atmosphere of the Earth, which by now have not been sufficiently studied reliably, and one of the ways to study them is mathematical modeling. The results of a computational experiment of the initial stage of ionization of a neutral gas are presented, which can help in further investigation of such a process.

ECOLOGICAL CONSEQUENCES OF THE UNDERGROUND NUCLEAR EXPLOSION IN KHARKIV REGION

The article covers an event that has been hidden for fifty years, namely the failure of a nuclear explosion at Kharkiv region. The possible ecological consequences of the mentioned event are analyzed. Data from different sources are compared for further planning of researches of an ecological condition of district. The basis for creating a system for studying the environmental consequences of a nuclear explosion at the time of its implementation and at present is provided. The basics of standard calculations of probable exposure of the population, which had to be carried out immediately after the explosion, are provided, and systemic recommendations for further environmental control in the designated area are offered.

Digital comparative analysis of simulation results of radioactive deposition field of nuclear explosion

The radioactive settlement of nuclear explosion is simulated by Lagrange particle diffusion model. The simulated settlement map and the measured data map are digitally extracted into the same format. The effectiveness measurement (MOE) method and normalized absolute difference (NAD) method are used to conduct numerical comparative analysis between each dose simulation area and the measured area.