UDC 550.844+546.791.027+632.126

https://doi.org/10.26516/2541-9641.2025.4.73

EDN: STZRHL

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Earthquakes of the Baikal Rift System in 2025: Decrease in Seismicity without Sufficient Changes in Hydrogeodynamics

S.V. Rasskazov^1,2, E.P. Chebykin^1,3, S.V. Snopkov^2,4, A.M. Ilyasova¹, I.S. Chuvashova¹

¹Institute of the Earth's Crust SB RAS, Irkutsk, Russia

²Irkutsk State University, Irkutsk, Russia

³A.P. Vinogradov Institute of Geochemistry SB RAS, Irkutsk, Russia

⁴Irkutsk National Research Technical University, Irkutsk, Russia

Abstract. In the context of the 10-12-year seismic cycles development in the Baikal Rift System (BRS), seismicity in 2025 decreases with the transition from episodic displaying of strong earthquakes of the Baikal-Khubsugul and North Baikal-Hangay reactivations of 2020-2024 (energy class K=13–15.7) to moderate and weak earthquakes of the seismic cycle middle (K<13). Respectively, the content of the thermophilic component Si in groundwater at station 27 of the Kultuk area slightly decreases in 2025 relative to 2020–2024 values. Meanwhile, other groundwater parameters of 2025 (²³⁴U/²³⁸U activity ratio, concentrations of U, ²³⁴U, Li, and Na) preserve signatures that are characteristic of 2020–2024. The further course of the BRS seismic cycle depends on the balance of forces generated in the Japan-Baikal geodynamic corridor and Sayan-Mongolian sector of the Indo-Asian Convergence. Various scenarios for the transition to future strong seismic activities are possible. The direction of evolution of the seismic process will be determined through trends of hydrogeodynamic parameters of groundwater.

Keywords: groundwater, monitoring, hydrogeochemistry, oxidation-reduction potential, earthquakes, Baikal

Earthquakes of the Baikal Rift System in 2025: Decrease in Seismicity without Sufficient Changes in Hydrogeodynamics

S.V. Rasskazov^1,2, E.P. Chebykin^1,3, S.V. Snopkov^2,4, A.M. Ilyasova¹, I.S. Chuvashova¹

¹Institute of the Earth's Crust SB RAS, Irkutsk, Russia

²Irkutsk State University, Irkutsk, Russia

³A.P. Vinogradov Institute of Geochemistry SB RAS, Irkutsk, Russia

⁴Irkutsk National Research Technical University, Irkutsk, Russia

Abstract. In the context of the 10-12-year seismic cycles development in the Baikal Rift System (BRS), seismicity in 2025 decreases with the transition from episodic displaying of strong earthquakes of the Baikal-Khubsugul and North Baikal-Hangay reactivations of 2020-2024 (energy class K=13–15.7) to moderate and weak earthquakes of the seismic cycle middle (K<13). Respectively, the content of the thermophilic component Si in groundwater at station 27 of the Kultuk area slightly decreases in 2025 relative to 2020–2024 values. Meanwhile, other groundwater parameters of 2025 (²³⁴U/²³⁸U activity ratio, concentrations of U, ²³⁴U, Li, and Na) preserve signatures that are characteristic of 2020–2024. The further course of the BRS seismic cycle depends on the balance of forces generated in the Japan-Baikal geodynamic corridor and Sayan-Mongolian sector of the Indo-Asian Convergence. Various scenarios for the transition to future strong seismic activities are possible. The direction of evolution of the seismic process will be determined through trends of hydrogeodynamic parameters of groundwater.

Keywords: groundwater, monitoring, hydrogeochemistry, oxidation-reduction potential, earthquakes, Baikal

References

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Vorobiev V.S. Model of distribution of terrigenous reservoirs and salinized sandy-gravelly deposits within the fields of the central part of the Nepa Arch / V.S. Vorobiev, I.V. Chekanov, Ya.S. Klinovaya // Geology of Oil and Gas. Moscow : 2017, No. 3. P. 47–60.

Vorobiev V.S. Patterns of distribution of reservoirs and salinization intervals in the Vendian terrigenous complex of the Chonsk group of fields (Eastern Siberia) / V.S. Vorobiev, L.N. Shakirzyanov, E.A. Zhukovskaya // Abstracts of the conference "Problems and Experience in Developing Hard-to-Recover Reserves of Oil and Gas Condensate Fields". Saint Petersburg : 2015.

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Rasskazov Sergei Vasilevich

doctor of geological and mineralogical sciences, professor,

664025, Irkutsk, Lenin st., 3,

Irkutsk State University, Faculty of Geology,

Head of Dynamic Geology Char,

664033, Irkutsk, Lermontov st.,

128, Institute of the Earth's Crust SB RAS,

Head of the Laboratory for Isotopic and Geochronological Studies,

tel.: (3952) 51–16–59,

еmail: rassk@crust.irk.ru

 

Snopkov Sergei Viktorovich,

Candidate of Geological and Mineralogical Sciences,

664003, Irkutsk, Lenin str., 3,

Irkutsk State University, Faculty of Geology,

Associate Professor,

664074, Irkutsk, Kurchatov st., 3,

Siberian School of Geosciences, Irkutsk National Research Technical University,

Leading Researcher,

email: snopkov_serg@mail.ru.

 

Aslamov Ilya Aleksandrovich,

Candidate of physical and mathematical sciences, Senior Researcher,

664033, Irkutsk, Ulan-Batorskaya st., 3,

Limnological Institute SB RAS,

еmail: ilya_aslamov@bk.ru

 

Arkhipenko Vladislav Ivanovich,

664033, Irkutsk, st. Ulan-Batorskaya, 3,

Limnological Institute SB RAS,

Main Electronics Engineer,

еmail: vladarxip@gmail.com

 

Ilyasova Aigul Maratovna,

candidate of geological and mineralogical sciences,

664033, Irkutsk, Lermontov st., 128,

Institute of the Earth's Crust SB RAS,

Leading Engineer,

еmail: ila@crust.irk.ru

 

Chebykin Eugene Pavlovich,

Candidate of Chemical Sciences,

664033, Irkutsk, Lermontov st., 128,

Institute of the Earth's Crust SB RAS,

664033, Irkutsk, Favorskiy st., 1A,

A.P. Vinogradov Institute of Geochemistry SB RAS,

Senior Researcher,

еmail: epcheb@yandex.ru

 

Chuvashova Irina Sergeevna,

candidate of geological and mineralogical sciences,

664033, Irkutsk, st. Lermontov, 128,

Institute of the Earth's Crust SB RAS,

Senior Researcher,

tel.: (3952) 51–16–59,

email: chuvashova@crust.irk.ru