The paper presents results of microseismic and electromagnetic studies of a landslide in the Suusamyr River valley (northern Tien Shan, Kyrgyzstan) and laboratory pulse transmission experiments on soil samples from the landslide. Spectral and polarization patterns of microseisms on the slope show that the main portion of seismic energy in the frequency range of 120 to 210 Hz is related to microcracking in zones of stress concentration. The high-resolution image of the landslide obtained by the applied techniques of areal TEM soundings and the high sensitivity of seismic parameters to the stress-strain state of the soil demonstrated in the pulse transmission experiments confirm the efficiency of geophysical methods in investigation of landslides and slope stability.

The conditions of the performed experiments were as follows. A three-component receiver was installed in a thermostatic pavilion of the seismological station "Novosibirsk". A vibrator (force amplitude 50-100 tons) was functioning out-of-doors. The source-receiver distance was 49 100 m. Vibration sessions were performed each one-two weeks during 1.5 years. The experiments have shown that seismograms are highly reproducible when obtained under summer ground conditions (from June till October) or in winter (from January till March). The "summer" seismograms strongly differ in appearance from the "winter" ones, but the domains of the first arrivals of P waves show the presence of stable waves. These waves are virtually the same in the "summer" and "winter" seismograms. They are recommended for monitoring the stress-strained state of a medium by periodical vibrating dangerous zones of active seismicity. The high reproducibility of vibroseismic signals (under the same seasonal conditions) enables one to register wave fields on large areas by resetting receivers. This method was used to reveal fracture sites in the Baikal Rift Zone from changes in the spectrum of received vibroseismic signals.