The macroseismic equation,giving the convergent solution（regardless of magnitude） for relative intensity at lg R-0,was derived. Investigation of seismically resistant characteristics of rocks in the Baikal region together with literary data and unified theory allowed one to evaluate the equipotential source surface. The constancy of earthquake intensity at the boundary of a source,the radiator of elastic waves in the crust,is established. This made it possible to carry out transition from the main parameter of an earthquake, the magnitude, to the quantitative calculation of intensity with distance from a source. Bilinear dependence of intensity（density of energy flux） on a distance is obtained. Correlation between density of energy flux and relative intensity is given. Intensity of oscillatory loads depending on physical characteristics of grounds-building bases was derived. The proposed method of quantitative prediction of large seismic effects in seismological aspect is one of the possible methods to provide the detailed seismic zoning and microzoning of the territories.