Introduction. In seismic zoning of the survey area, a mandatory condition is the determination of seismic hazard. It is determined by the maximum possible seismic impacts expressed in points of the macroseismic intensity scale, as well as in peak ground acceleration and dynamic coefficient spectra.

Aim. The aim of the article is to present a methodology for a comprehensive assessment of seismicity using the example of hydraulic structures (HS) of a sludge storage facility and to identify the features of the seismic characteristics of the soil.

Materials and methods. These parameters are taken into account in the design, construction and operation of buildings and structures in seismically active areas. In addition, dominant and resonant frequencies of the ground strata are determined, which are necessary for structural stability calculations and for tuning the natural vibration frequencies of the designed structure from the existing vibration frequencies in the ground strata. Such a set of geophysical surveys is included in the practice of the research laboratory of geophysics of JSC “VNII Galurgiya” when conducting engineering geological surveys at various stages of design and operation of capital construction facilities, including hydraulic structures. Dams and dams of sludge storages (slurry storages, tailings storages) and/or other objects placed on the territory of sludge storages, as a rule, belong to hydraulic structures of II, III and IV classes of danger.

Conclusions. The paper presents the possibilities of an integrated approach to seismic microzonation of the sludge storage area, which allows to reduce the risk of underestimation of factors of various origins affecting seismic intensity under different geological conditions. In conclusion, the authors highlighted a number of conclusions related to the methodology and principles of the work.

Introduction. The concept of “reference soil” was not formalized initially neither by the author of the method of seismic stiffnesses, nor later by the authors of modifications of the same method of seismic intensity estimation due to ground conditions. At the same time, the characteristics of the reference soil determine the value of the seismic intensity increment, which in turn determines the value of the design seismic intensity.

Aim of the article is to substantiate the concept of “reference soil” and its actualization in the modern realities of seismic microzonation.

Materials and methods. Based on the study of literature sources, the criteria for the selection of reference soil are defined. At the same time, the shortcomings of the reference soil concept in the method of seismic stiffnesses are revealed. Instead of the concept of “reference soil” and the realization of an ambiguous procedure for selecting reference soils, it is proposed to introduce into practice the term “reference strata”, relative to which the value of seismic intensity increment is calculated.

Conclusions. It is shown that the values of seismic increments calculated by the method of reference soil and by the method of reference thickness for the same models of soil strata have the same trend. In this case, the reference stratum acts as a reference on which macroseismic estimates of seismic intensity and seismic intensity increments at the survey site are “docked”.