GEOLOGICAL, GEOPHYSICAL AND MACROSEISMIC DATA
ON THE SEPTEMBER 28, 2019,
Mw = 5.1 EARTHQUAKE OCCURRED
AT THE NORTH-EAST OF THE BAIKAL RIFT


A.I. Seredkina1, Ya.B. Radziminovich 2, V.I. Melnikova2, N.A. Gileva3


1 Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation,
Russian Academy of Sciences, Moscow, Troitsk, Russia

2 Institute of the Earth’s Crust, Siberian Branch of the Russian Academy of Sciences, Irkutsk,
Russia

3 Baikal Branch of Federal Research Center «Geophysical Survey of Russian Academy
of Sciences», Irkutsk, Russia


Corresponding author: A.I. Seredkina, e-mail: ale@crust.irk.ru


Abstract. This paper considers the September 28, 2019 earthquake occurred at the north-eastern flank of the Baikal rift zone (BRZ) and called the Lenger earthquake according to its location. A seismic moment tensor and a hypocentral depth of the seismic event are calculated from the data on surface wave amplitude spectra with additional information on P-wave first-arrival polarities recorded at regional stations. The hypocentral depth is found to be 11–12 km, moment magnitude Mw = 5.1 and scalar seismic moment M0 = 5·1016 N·m. The earthquake source was formed under the influence of the horizontal submeridional extension and subhorizontal NE-SW compression. The latter approximately coincides with the azimuth of the fast S-wave velocity in the upper mantle obtained from SKS-splitting and surface wave tomography data. The Lenger earthquake was felt at the epicentral distances more than 600 km. Comparison of its macroseismic effects with effects of other strong seismic events of the study area demonstrates that the regional equation of macroseismic field should be actualized for the territory of the north-eastern flank of the BRZ. Analysis of the obtained data along with the available information on stress-strain field of the crust of the considered area evidences that the geodynamical pattern of the conjunction zone of the north-eastern flank of the BRZ and the Olekma-Stanovoy orogenic system influences the low active Transbaikalia block. However, due to low tectonic activity, the period of accumulation of tectonic stresses, which are sufficient for occurrence of relatively strong seismic events, is larger than in regions with high level of tectonic activity.


Keywords: earthquake, seismic moment tensor, surface waves, macroseismic data, seismotectonic deformations, anisotropy, Baikal rift.


About the authors

SEREDKINA Alena Igorevna – Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences. Russia, 108840, Moscow, Troitsk, Kaluzhskoye Highway, 4. E-mail: ale@crust.irk.ru

RADZIMINOVICH Yan Borisovich – Institute of the Earth’s Crust, Siberian Branch of the Russian Academy of Sciences. Russia, 664033, Irkutsk, Lermontova st., 128. E-mail: ian@crust.irk.ru

MELNIKOVA Valentina Ivanovna – Institute of the Earth’s Crust, Siberian Branch of the Russian Academy of Sciences. Russia, 664033, Irkutsk, Lermontova st., 128. E-mail: vimel@crust.irk.ru

GILEVA Nadezhda Alekseevna – Baikal Branch of Federal Research Center «Geophysical Survey of Russian Academy of Sciences». Russia, 664033, Irkutsk, Lermontova st., 128. E-mail: nagileva@crust.irk.ru


Cite this article as: Seredkina A.I., Radziminovich Ya.B., Melnikovа V.I., Gileva N.A. Geological, geophysical and macroseismic data on the September 28, 2019, Mw = 5.1 earthquake occurred at the North-East of the Baikal rift, Voprosy Inzhenernoi Seismologii (Problems of Engineering Seismology). 2020. V. 47, No. 1. P. 5169 [in Russian]. https://doi.org/10.21455/VIS2020.1-3


English translation of the article will be published in Seismic Instruments, ISSN: 0747-9239 (Print) 1934-7871 (Online), https://link.springer.com/journal/11990