Vertical and horizontal components of the lake Baikal electrotelluric field and their relation to the electric conductivity

Synchronous observations of the electrotelluric field were performed on the lake ice and the coast. The ice-based vertical/horizontal field ratio at periods of a few seconds to a few minutes ranges from a few hundredths to a few thousandths, which is comparable to the noise level. The results of these observations favor a plane wave model. At the coastal station, the vertical and horizontal fields are similar, which is related to geoelectric heterogeneity of the medium. An electric tipper is used to control the behavior of heterogeneity in the spectral-time domain. Anomalous changes associated with earthquakes of K >= 12 are revealed from data of the tipper monitoring at epicentral distances of up to 300 km. A longitudinal MTS curve free from the effect of local geoelectric heterogeneities is obtained from ice-based data. Deep conducting layers are recognized as minimums in this curve.