In 1980s of the last century, several thousands soundings were performed by the methods of transient electromagnetic sounding (TEM) and vertical electrical sounding (VES) in the region of the Chuya depression. The coaxial symmetric array was used for TEM sounding. In consequence of field material interpretation using the “ERA” program system, the detailed geoelectrical model of the Chuya depression was constructed. The map of earthquake epicenters evidences that large-scale events were not observed in the depression region during significant time interval.

After the destructive Altay earthquake in summer 2004, repeated electromagnetic measurements were performed in the western part of the Chuya depression along the traverses of 1980s keeping the array sizes. The main objective of these works was to determine up-to-date geoelectrical parameters of the section and to ascertain dynamics of changes in these parameters after the seismic event. The basic cause of significant changes in electrical parameters (up to 100% and more) after a seismic event is areal redistribution of interstitial and formation water in the epicentral region of the Alrtay earthquake as demonstrated by the hydrogeological data.