EVALUATION OF SEISMIC IMPACTS OF STRONG EARTHQUAKES IN VARIOUS PERMAFROST AND SEISMIC ZONES OF THE MONGOLIAN-SIBERIAN REGION

Based on the study of the features of seismicity within the limits of continuous permafrost and in transitional climatic zones, the influence of natural and climatic factors on the magnitude of seismic impacts is revealed. The results of studies carried out to develop a regional methodology for predicting the parameters of seismic effects of strong earthquakes in the Mongolian-Siberian region during permafrost degradation are summarized. These results are based on the data of complex geophysical measurements. They are aimed at developing methods and techniques for assessing the seismic impacts of strong earthquakes on critical engineering structures located within the permafrost zone and at developing recommendations for conducting seismic micro zoning in various seismic-climatic zones of Siberia and Mongolia, taking into account potential earthquake sources.

The main goal of this study is to use the data obtained in planning and construction in seismically active permafrost areas. The developed methods and approaches are presented at the current level of requirements for the design of earthquake-resistant structures in the permafrost zone in specific areas: at the Uyanga site sum, located in Northern Mongolia, and at the Tupik site (using the example of the construction of a tailings dam), located in Russia in the Zabaykalsky Krai (Transbaikal Territory). The first section is located in the zone of insular permafrost with a probability of earthquakes of VIII-degree intensity. The second is in the area of continuous permafrost with a likelihood of VII-degree earthquakes.

The proposed and implemented integrated methodological approach makes it possible to obtain at the present level of research for the natural and predicted state of soils in the foundations of designed structures a set of seismic characteristics (accelerograms, spectra, frequency characteristics) and the main parameters of seismic effects for predicted strong earthquakes (maximum accelerations, prevailing frequencies, maxima spectra and resonant frequencies). The noted set of characteristics and parameters of seismic effects meets the modern requirements of designers. It should be accounted for earthquake-resistant structures located in various seismic-climatic zones of the Mongolian-Siberian region.

1. Building Regulations II-7-81*, 2018. Construction in Seismic Areas. SP 14.13330.2018. Moscow, 117 p. (in Russian).

2. Dzhurik V.I., Bryzhak E.V., Serebrennikov S.P., Eskin A.Yu., 2020. The Spectral Behavior of Ground Coseismic Motion in the Baikal Region: Effect of Seasonal Thawing-Freezing Cycles. Russian Geology and Geophysics 61 (8), 929–936. https://doi.org/10.15372/RGG2019123.

3. Dzhurik V.I., Drennov A.F., Serebrennikov S.P., Bryzhak E.V., Eskin A.Yu., 2015. A Study of Dynamic Parameters for Earthquakes in the Baikal Rift Zone in Order to Derive the Expected Seismic Shaking. Journal of Volcanology and Seismology 9, 339–348. https://doi.org/10.1134/S0742046315050036.

4. Dzhurik V.I., Klyuchevsky A.V., Serebrennikov S.P., Demyanovich V.M., Batsaikhan Ts., 2009. Seismicity and Seismic Zoning of the Territory of Mongolia. IEC SB RAS, Irkutsk, 420 p. (in Russian).

5. Dzhurik V.I., Serebrennikov S.P., Bryzhak E.V., Eskin A.Y., 2021. A Preliminary Seismic Hazard Assessment of the Sakhalin–Mainland Area for a Critical Linear Structure. Russian Journal of Pacific Geology 15, 456–466. https://doi.org/10.1134/S1819714021050031.

6. Gileva N.A., Kobeleva E.A., Radziminovich Ya.B., Melnikova V.I., Chechelnitsky V.V., 2020. The September 21, 2020, Mw=5.5, Bystraya Earthquake in the Southern Baikal Region: Preliminary Results of Instrumental and Macroseismic Observations. Problems of Engineering Seismology 47 (4), 55–71 (in Russian). https://doi.org/10.21455/VIS2020.4-4.

7. Khilko S.D., Kurushin R.A., Kochetkov V.M., Misharina L.A., Melnikova V.I., Gilyova N.A., Lastochkin S.V., Baljinnyam I., Monkhoo D., 1985. Earthquakes and Basis for Seismic Zoning of Mongolia. Nauka, Moscow, 224 p. (in Russian).

8. Pavlov O.V. (Ed.), 1988. Assessing the Influence of Ground Conditions on Seismic Hazard. Methodological Guide to Seismic Microzoning. Nauka, Moscow, 223 p. (in Russian).