The article presents the results of studies conducted in the fall of 2008 in the southern part of Lake Baikal, where the Kultuk earthquake occurred. The impact of the earthquake on rocks and foundations of social and public buildings (hospitals, schools, etc.) in Slyudyanka, pos. Kultuk and in other settlements. A large amount of factual material on soil reinforcement by cementation was obtained during the demolition of residential buildings in the city of Irkutsk. It was established that the destruction of the foundations of buildings and structures, which occurred as a result of the Kultuk earthquake in the Slyudyansky region, is due to: a) in some cases, the almost total absence of a foundation cushion; b) a combination of rocky and dispersed soils at the base of the foundation that caused the heterogeneity of the bearing layer, which led to the destruction of the building; c) heterogeneity of the composition, state and properties of dispersed soils at the base of the foundations, when uneven deformation (compression) of the soil contributed to the emergence of a different amplitude system of oscillations of the foundation and walls of buildings during an earthquake.