Assessment of Adverse Engineering Geological Conditions during Seismic Microzonation of the Sentachan Mining and Refining Facility (Eastern Yakutia)

In this study, the authors used complex seismotectonic, geological and geophysical methods when carrying out scientific research, identifying unfavourable engineering geological conditions for the designed mining facility located in the cryolithozone, as well as when determining the level of basic seismic hazard and performing seismic microzonation. The seismotectonic methods consisted in establishing the relationship between the distribution of local earthquake epicentres and active geological structures. The geophysical studies employing the methods of near-surface seismic tomography and electrical resistivity tomography allowed obtaining of detailed and reliable information on the features of the engineering geological structure of the studied site required to assess the influence of soils on the seismic wave attenuation of possible earthquakes in the region, thus solving the issue of seismic microzonation. Seismotectonic studies consisted in determining the level of basic seismic hazard and were based mainly on previous field studies summarised in a number of published works, some of whose conclusions were used in this article. The analysis of geophysical data allowed the authors to establish probable location of the distributions of ice and ice-rich permafrost, as well as the heterogeneity of soil conditions that affect their behaviour under dynamic loads. The calculated values of probable earthquake intensities allowed the authors to determine the level of maximum earthquake intensity at the designed industrial sites of the mining and refining facility.