We present the results of synchronous observations of microbaric oscillations and variations of electric and magnetic fields during large fires of man-made origin in Moscow. The main instrumental observations were carried out at the Center for Geophysical Monitoring in Moscow at the Sadovsky Institute of Geosphere Dynamics of Russian Academy of Sciences (CGM IDG RAS). Using an analysis of the data, we show that large fires in a megalopolis are manifested in microbaric variations and variations of the electric and geomagnetic fields in the surface atmosphere. Under certain conditions (the absence of intense natural movements of air masses and sufficiently strong heating of the atmosphere in the combustion source), fires can lead to an increase in wind speed and direction in an area up to 25 km. The emergence of a dynamic region with altered thermodynamic characteristics above the fire zone causes the formation of infrasonic waves during the period of the most intense combustion. Strong fires lead to an increase in the concentration of fine particles in the surface atmosphere.

Анализируется частота фундаментальной моды F собственных колебаний Земли 0S2, выделенная в спектрах геомагнитных вариаций в Геофизической обсерватории (ГФО) «Михнево» ИДГ РАН, в период сильных землетрясений. Показано, что величина F принимает разные значения в зависимости от даты события, причем значения F выше в периоды, характеризующиеся уменьшением скорости вращения Земли, и ниже - в периоды ее увеличения. По результатам сопоставительного анализа результатов магнитных измерений и данных каталога открытого доступа IERS получена эмпирическая зависимость между вариациями F и скоростью вращения Земли. The frequency of the fundamental mode F of the Earth’s natural oscillations 0S2, identified in the spectra of geomagnetic variations at the Mikhnevo observatory of the IDG RAS, during strong earthquakes is analyzed. It is shown that the value of F takes different values depending on the date of the event, and the values of F are higher during periods characterized by a decrease in the Earth’s rotation rate, and lower during periods of its increase. Based on the results of a comparative analysis of the results of magnetic measurements and the data of the IERS open access catalog, an empirical relationship was obtained between the variations in F and the Earth’s rotation rate.

Abstract—The disturbances of the geomagnetic field in the surface atmosphere were considered during a series of strong earthquakes that occurred on April 2–3, 2024, in the vicinity of the island of Taiwan. The data from the Mikhnevo Geophysical Observatory of the Sadovskii Institute of Geosphere Dynamics, Russian Academy of Sciences, and the observatories of the international INTERMAGNET network were analyzed. It was shown that in the absence of sole-related global disturbances of the Earth’s magnetic field, earthquakes were accompanied by geomagnetic variations with a maximum amplitude of 10 nT and a total duration of about four hours. The delay time of the magnetic effect relative to the main shock of the first earthquake was 60 min. The ionospheric effect of the event considered was established in the form of variations in the critical frequency of the F2 layer of the ionosphere on the basis the ionograms of height–frequency sounding obtained at the Okinawa ionospheric monitoring station and freely available on the website of the Japanese National Institute of Information and Communication Technologies.

— The geophysical effects of a strong seismic event as two earthquakes with magnitudes of 6.8 and 4.9 occurred on September 8, 2023, in Morocco at close times 22:11 and 22:30 UTC with an epicentral distance between the foci of ~4 km were considered. The data of a number of INTERMAGNET observatories and the magnetic recording results obtained at the Mikhnevo Geophysical Observatory of Sadovsky Institute of Geosphere Dynamics of Russian Academy of Sciences, were used. In the absence of considerable global disturbances of the Earth’s magnetic field, earthquakes were accompanied by a series of three positive bay-shaped geomagnetic variations with a maximum amplitude from ~1 to ~10 nT, following each other after ~60 min. The maxima of the induced magnetic field variations were observed almost synchronously at a distance from ~800 to ~10000 km. The magnetic effect delay time relative to the main shock of the first earthquake was ~70 min. Taking into account the almost planetary nature and high synchronicity of the magnetic field disturbances caused over a significant range of distances, as well as the time delays corresponding in order of magnitude to the travel time of the seismic signal of a distance multiple of the Earth’s dimension, it is suggested that the magnetic effect of the seismic event in question was caused by a global source such as an excited geodynamo. The ionospheric effect of the seismic event under consideration is reported as variations in the critical frequency f 0 F 2 calculated from the data obtained by the ground-based sounding station of the del Ebre Observatory.

The variations of the Earth’s magnetic field in the period 2013−2023 are considered on the basis of data from the INTERMAGNET network observatories located in the South Pacific Ocean. It was shown that El Niño in 2015 was accompanied by anomalous geomagnetic variations with an amplitude of up to 120 nT with a well-manifested increase in their mean-square deviation by 1.5 times relative to the average values of 2013. For the period from the end of 2022 to the beginning of 2023, a dramatical increase in the variations of the geomagnetic field and an increase in their mean-square deviation by 2.5 times relative to 2021 was recorded. This fact may indicate the beginning of the activation of a strong El Niño, the maximum intensity of which should be expected in 2024.

We present the results of instrumental observations of acoustic oscillations, geomagnetic variations and variations of the atmospheric electric field during the fall and explosive destruction of the bolide in the southeast of Turkey on September 02, 2023. It is shown that the destruction of the bolide under the action of aerodynamic forces, which occurred in three stages, was accompanied by an acoustic signal of a characteristic shape and manifested in variations of the magnetic and electric fields in the near-surface layer atmosphere. The total energy of the event, estimated by the acoustic effect, was ~ 9×1012 J, which corresponds to about 2.15 kt in TNT equivalent. The maximum amplitude of geomagnetic variations caused by the explosion of the bolide ranged from 0.2 to 2.1 nT depending on the distance. At the same time, the amplitude of variations of the vertical component of the atmospheric electric field at the Mikhnevo observatory (distance ~1900 km) was ~70 V/m. The ionospheric effect of the event under consideration is demonstrated in the form of variations of the critical frequency f0F2 obtained as a result of processing ionograms of height-frequency sounding of the ionosphere at the Rome station.

The results of instrumental observations of acoustic oscillations, geomagnetic variations, and variations in the atmospheric electric field are presented for the period of fall and explosive decomposition of a bolide in southeastern Turkey on September 2, 2023. It is shown that its decomposition under the influence of aerodynamic forces, occurred in three stages, was accompanied by an acoustic signal of specific morphology, and resulted in variations of the magnetic and electric fields in the subsurface atmospheric layer. The total energy of the event estimated from the acoustic effect was ~9 × 10 12 J, which approximately corresponds to 2.15 kt of TNT. The maximum amplitude of geomagnetic variations induced by the bolide explosion varied from 0.2 to 2.1 nT depending on the distance. The amplitude of variations of the vertical component of the atmospheric electric field in the Mikhnevo Geophysical Observatory (at a distance of ~1900 km) was ~40 V/m. This event showed an ionospheric effect in the form of variations in the critical frequency f 0 F2, which was a result of processing the ionograms of height-frequency sounding of the ionosphere at the Rome station.

An analysis of variations in the microbaric background and the terrestrial magnetic and electric fields in the surface layer of the atmosphere accompanying strong earthquakes that occurred on February 6, 2023, in Turkey, is presented. The analysis involved the results of instrumental observations performed at the Moscow Center for Geophysical Monitoring and the Mikhnevo Observatory (Institute of Geospheric Dynamics, Russian Academy of Sciences), as well as the data obtained by a number of magnetic observatories of the INTERMAGNET network. It is shown that, in addition to the seismic effect, these earthquakes were accompanied by variations in the magnetic and electric fields, as well as by the generation of infrasonic waves recorded at a considerable distance from the sources.

The response of the microbaric background and variations in the Earth’s magnetic and electric fields to the paroxysmal activity of the Stromboli Volcano (October 9, 2022, Italy) was analyzed using the results of instrumental observations carried out in the surface atmosphere. The stage of active volcanic eruption was accompanied by the generation of an acoustic signal and pronounced variations in the geomagnetic and atmospheric electric fields at considerable distances both during the period of volcano activity and with the arrival of the infrasonic wave at the observation point. The volcanic eruption was noted to cause a response as critical frequency variations of the F 2 layer in the ionosphere.

An Erratum to this paper has been published: https://doi.org/10.1134/S1028334X23070103

Based on the results of instrumental observations of geomagnetic variations at the Mikhnevo observatory of the IDG RAS and data from the IERS catalog, it was found that the frequency F of the main spheroidal mode of the Earth’s natural oscillations 0S2, distinguished in the spectra of magnetic field variations, changes with time, and the values of F are higher during periods of a decrease in the rotation speed Earth and below with its increase, An empirical relationship between the variations of F and the speed of the Earth’s rotation is obtained,

An analysis of the lithological, isotope-geochemical, and micropaleontological parameters of the surface layer of bottom sediments in the North Atlantic was made at 26 stations on the profile along 59.5° N. The distribution of humidity and granulometric composition of sediments reflects vertical/circumcontinental zonality, since fine-grained and water-saturated material accumulates in the deepest parts of the Iceland Basin and the Labrador and Irminger seas, which are farthest from land. Larger masses of calcium carbonate are also formed there, but organic carbon is unevenly distributed. Both vertical/circumcontinental and climatic (circulation of the warm North Atlantic water) zonalities affect the mineral composition of the sediment fraction 0.063 mm. The accumulation of diatoms, radiolarians, and planktic foraminifers in sediments reflects both vertical/circumcontinental and, to a greater extent, climatic zonality. Variations in the isotopic oxygen and carbon ratios in the shells of benthic and planktic foraminifers require a complex interpretation involving data on the parameters of various surface and bottom water masses. The distribution of planktic microfossil assemblages according to cluster analysis shows areas of distribution of different water masses with a clear boundary along the eastern margin of the Subpolar Gyre. The distribution of “cluster” assemblages of benthic foraminifers does not correspond much to that of planktic microfossils, reflecting the division of the water area into abyssal and shallow water areas.

We present the data of instrumental observations made at the Mikhnevo geophysical observatory of the IDG RAS of magnetic field variations and the response of microbaric oscillations and the electric field in the Earth’s surface atmosphere to a strong magnetic storm on April 23, 2023 (Kp = 8). When determining the response of the ionosphere to a magnetic disturbance in the form of a change in the critical frequency of the F2 layer, we use the results of ionospheric sounding performed at the IAP (Leibniz-Institut Fur Atmospharen Physik). It is shown that during periods of maximum magnetic field variations, increased microbaric variations are recorded and increased electric field variations are noted. The magnetic storm was also accompanied by a change in the critical frequency f0F2, as well as in the spectral characteristics of variations in the electric field strength.

The results of instrumental observations carried out at observatories of the INTERMAGNET network and at the Wakkanai ionospheric sounding station were used to show that the vigorous effusion–explosion eruption of Shiveluch Volcano occurring on April 10, 2023 was accompanied by variations in the Earth’s magnetic field, as well as by changes in the critical frequency of the ionospheric F 2 layer.

The magnetic effects of strong earthquakes are considered using the example of a unique event: two underwater earthquakes of magnitude 6.0 and 7.3 that occurred on March 16, 2022 at close times (at 14:34 and 14:36 UTC, respectively) with a distance between sources of ~11 km. With the use of data from the Mikhnevo geophysical observatory of the IDG RAS (MHV) and a number of magnetic observatories of the INTERMAGNET international network, it is shown that in the absence of global geomagnetic disturbances, earthquakes were accompanied by characteristic variations of the Earth’s magnetic field recorded as a train of alternating geomagnetic field oscillations with an amplitude of ~2–8 nT and a period of ~30 min almost simultaneously at ~15:30 UTC by all magnetic observatories located at distances from 210 to ~13 000 km, as well as by variations in the periods of passage of the seismic and infrasonic signal in the MHV.

An analysis of variations in the microbaric background, magnetic and electric fields in the surface layer of the atmosphere, accompanying strong earthquakes on February 6, 2023 in Turkey, is presented. The analysis involved the results of instrumental observations performed at the Center for Geophysical Monitoring of Moscow and the Mikhnevo observatory of the IDG RAS, as well as data obtained by a number of magnetic observatories of the INTERNAGNET network. It is shown that, in addition to the seismic effect, earthquakes were accompanied by variations in the magnetic and electric fields, as well as the generation of infrasonic waves recorded at a considerable distance from the sources.

— Analysis of the lithological, isotope-geochemical, and micropaleontological parameters of the surface layer of bottom sediments in the North Atlantic was carried out at 26 stations on the profile along 59.5° N. The distribution of moisture content and grain size of sediments reflects vertical/circumcontinental zoning, since fine-grained and water-saturated material accumulates in the deepest parts of the Iceland Basin and the Labrador and Irminger seas, which are farthest from land. Larger masses of calcium carbonate also form there, but organic carbon is unevenly distributed. Both vertical/circumcontinental and climatic (circulation of warm North Atlantic water) zoning affect the mineral composition of the >0.063 mm sediment fraction. Accumulation of diatoms, radiolarians, and planktic foraminifers in sediments reflects both vertical/circumcontinental and, to a greater extent, climatic zoning. Variations in the oxygen and carbon isotopic ratios in the tests of benthic and planktic foraminifers require comprehensive interpretation involving data on the parameters of various surface and bottom water masses. The distribution of planktic microfossil assemblages according to cluster analysis shows distribution areas of different water masses with a distinct boundary along the eastern margin of the Subpolar Gyre. The distribution of cluster assemblages of benthic foraminifers does not correspond much to that of planktic microfossils, reflecting division of the study region into abyssal and shallow areas.

—During a series of destructive earthquakes in Turkey on February 6, 2023, in particular, two strong earthquakes with magnitudes 7.8 and 6.7 immediately following each other, the results of instrumental observations of microbaric and geomagnetic variations made in the surface layer of the atmosphere, as well as variations of the electric field and the critical frequency of the regular F 2 layer of the ionosphere are presented. It is shown that the earthquakes were accompanied by variations of magnetic and electric fields, generation of infrasound waves recorded at a considerable distance from the sources, as well as variations of the critical frequency f 0 F 2.

Based on the results of instrumental observations of geomagnetic variations at the Mikhnevo Observatory of the Institute of Geosphere Dynamics, Russian Academy of Sciences, and the data from the IERS catalog, it is found that the frequency F of the fundamental spheroidal mode 0 S 2 of the Earth’s free oscillations, distinguished in the spectra of magnetic field variations, changes with time; the values of F are higher when the speed of the Earth’s rotation decreases and are lower when it increases. An empirical relationship between the variations in F and the speed of the Earth’s rotation is obtained.

The analysis of the relationship of benthic foraminifera and of natural radionuclides (232Th, 238U and 226Ra) distribution in the deep-water sediments of the North Atlantic in the section of 60○N crossing the arctic front is fulfilled. A oppositely directed correlation between the distribution of natural radionuclides in sediments and Alabaminella Weddellensis (Rs = 0.8) and Cibicidoides wuellerstorfi (Schwager, 1866) (Rs = –0.68) species occupying different ecological niches was revealed. The weighted radiation dose is calculated. The dose values obtained are in the range of 0.63–2.16 μGr/hour. It is assumed that under the conditions of measured background radiation, the effect of radiation hormesis in foraminifera manifests itself, stimulating their development.