The regulatory framework for seismic microzoning in Russia has recently been supplemented by a number of new generation documents. In particular, the document SP 283.1325800.2016 was adopted. In it for the description of spectral characteristics of a soil thickness the value of a maximum of coefficient of dynamism b was used. The scope of the normative document did not allow to describe in detail the method of obtaining and features of the use of this parameter, which is why it turned out to be an unusual innovation for prospectors. The article describes in detail how this value is obtained and how to use it. The ways of setting the standard values of the dynamic coefficient are analyzed. It is shown that the standard values do not cover the range of possible variations in both the properties of seismic effects and the reactions of the soil mass to these effects. The values of the maximum coefficient of dynamism can be significantly higher than the current normative values of 2.5. The importance of taking into account the internal structure of the soil mass is shown. Instead of soil categories the basic concept of construction, the defining features of engineering-seismological investigations in the study area, it is proposed to use the notion of model ground conditions. Special attention is paid to the consideration of nonlinear phenomena under strong seismic impacts. The effect of the nonlinearity of the stress-strain relationship on the spectral characteristics of the soil layer under strong seismic impacts is studied. It is shown that the nonlinearity significantly reduces the intensity of resonance processes in the soil massif.