THE BYSTRINSKOE EARTHQUAKE IN THE SOUTHERN BAIKAL REGION (21 SEPTEMBER, 2020, Mw = 5.4): MAIN PARAMETERS, PRECURSORS, AND ACCOMPANYING EFFECTS
K.Zh. Seminsky1, S.A. Bornyakov1,2, A.A. Dobrynina1,3, N.A. Radziminovich1,4, S.V. Rasskazov1,2, V.A. San’kov1,2, P. Mialle5, A.A. Bobrov1, A.M. Il’yasova1, D.V. Salko1, A.V. San’kov1, A.K. Seminsky1, E.P. Chebykin1,6, A.N. Shagun1, V.I. German1,7, Ts.A. Tubanov3, M. Ulzibat8
1Institute of the Earth’s Crust, Siberian Branch of the Russian Academy of Sciences, ul. Lermontova 128, Irkutsk, 664033, Russia
2Irkutsk State University, ul. Lenina 3, Irkutsk, 664003, Russia
3Geological Institute, Siberian Branch of the Russian Academy of Sciences, ul. Sakh’yanovoi 6a, Ulan-Ude, 670047, Russia
4Buryat of the Federal Research Center of the Geophysical Survey of the Russian Academy of Sciences, ul. Sakh’yanovoi 6a, Ulan-Ude, 670047, Russia
5Comprehensive Nuclear-Test-Ban Treaty (CTBTO) Preparatory Commission, Vienna International Centre, 1400 Vienna, POB 1200, Austria
6Limnological Institute, Siberian Branch of the Russian Academy of Sciences, ul. Ulan-Batorskaya 3, Irkutsk, 664033, Russia
7Krasnoyarsk Research Institute of Geology and Mineral Resources, pr. Mira 55, Krasnoyarsk, 660049, Russia
8Institute of Astronomy and Geophysics, Mongolian Academy of Sciences, Ulaanbaatar, POB 152, Mongolia
Keywords: Aftershocks, focal mechanism, precursors, faults, rock massif deformations, radon emanation, groundwater dynamics, Bystrinskoe earthquake in the southern Baikal region
Abstract
We present the preliminary results of a study of the Bystrinskoe earthquake, which occurred in the southern Baikal region on 21 September 2020 and was accompanied by shaking with an intensity of VI-VII on the MSK-64 scale in the epicentral area and with an intensity of V in large cities of southern East Siberia (Irkutsk, Angarsk, Usolye-Sibirskoe, Zakamensk, etc.). A preliminary characteristic of the seismic event is given on the basis of a comprehensive analysis of seismological, structural-tectonic, strain, emanation, and hydrogeochemical data obtained during the monitoring of hazardous geologic processes in the Baikal natural territory. We have estimated the seismologic parameters of the Bystrinskoe earthquake, characterized the accompanying phenomena, and identified the effects that are of interest as probable precursors of future strong earthquakes in the Baikal region. The data obtained suggest that the earthquake occurred in the zone of the Main Sayan Fault as a result of strike-slip movement along the W-NW fault. The earthquake focus was apparently located at a shallow depth, as evidenced by the duration of the shocks, macroseismic manifestations, and the strong rumble heard at different directions from the epicenter.
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