Long-term registration of small deformations of the Earth’s crust with the subsequent data processing is necessary for solving many actual problems. Such deformations are measured predominantly using unique laser measurer (deformograph). Experimental data allow us to investigate the frequency spectrum of deformations and on the basis of this analysis to draw conclusions about the level of seismic activity in the region. Variations of the tidal parameters allow estimating the parameters of the fractured zone. Measurements of deformations in two orthogonal directions are carried out using an original automated laser measurer for ultra-small movements of the Earth’s crust. The advantage of the laser measuring complex created for measurements in the mountain tunnel is that even in the presence of the atmosphere it possesses a high relative sensitivity of the order of 10-9-10-10 to small displacements in a wide range of oscillation periods of 100-107 s. It allows recording of the Earth’s own and tidal oscillations, deterministic daily variations of micro deformational oscillations, as well as features of the deformation processes in the Earth’s crust that accompany seismicity. This paper presents the results of long-term monitoring of oscillations of the Earth’s crust in the area of Lake Baikal, measured in the observatory Talaya in mountain tunnel with a laser meter.