PALEOSEISMIC STUDIES IN THE SELENGA DELTA, LAKE BAIKAL
Institute of the Earth's Crust, SB RAS
Journal: Problems of Engineering Seismology
Tome: 48
Number: 2
Year: 2021
Pages: 5-23
UDK: 551.248.2
DOI: 10.21455/VIS2021.2-1
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SMEKALIN O.P., ESKIN A.Y. PALEOSEISMIC STUDIES IN THE SELENGA DELTA, LAKE BAIKAL // . 2021. Т. 48. № 2. С. 5-23. DOI: 10.21455/VIS2021.2-1
@article{SMEKALINPALEOSEISMIC2021,
author = "SMEKALIN, O. P. and ESKIN, A. Y.",
title = "PALEOSEISMIC STUDIES IN THE SELENGA DELTA, LAKE BAIKAL",
journal = "Problems of Engineering Seismology",
year = 2021,
volume = "48",
number = "2",
pages = "5-23",
doi = "10.21455/VIS2021.2-1",
language = "English"
}
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Keywords: Tsagan earthquake, tsunami, paleoearthquake, trenching, shallow geophysics, Delta fault
Аnnotation: The article is devoted to the analysis of possible mechanisms of the formation of Proval Bay, Lake Baikal as a result of the Tsagan earthquake (12 January, 1862, М = 7.5 ± 0.3) and an assessment of the recurrence rate of catastrophic earthquakes in the Selenga delta based on the results of the study of seismic deformations. The previously unpublished results of seismogeological and geophysical studies are presented. Geological and geophysical studies of seismic dislocations in the epicentral zone of the Tsagan earthquake indicate that the source of this earthquake could be associated only with the largest Morskoi fault. The displacement along this fault, as well as along the zone of the feathering Delta fault, contributed to the occurrence of the tsunami and the landslide mechanism of the formation of Proval Bay. Paleoseismological interpretation of the trench sections and the results of radiocarbon dating show that in the north of the Selenga delta, events similar to the Tsagaan earthquake also occurred in 1399-1496, 1256-1401, 887-1150, 233 BC - 221 AD. This gives the average frequency of catastrophic earthquakes in the region as once every 500 years. Trenching and geophysical studies have established signs of upthrust-thrust kinematics of movements in Holocene, Pleistocene and Neogene-Quaternary sediments along the Delta fault. It is possible that the geodynamic compression regime manifested itself over relatively short time intervals. The conclusions drawn do not contradict the geological and geomorphological situation in the region, historical information about the dislocations and surface effects of the Tsagaan earthquake.