A new tectonic map of the Vendian-Silurian stage in the Lena-Tunguska petroleum province has been compiled following special principles and methodology, on the basis of the pioneer digital version of the 1: 1,000,000 structural map of the Vendian-Cambrian surface for the same region. Mapping revealed the distribution and morphology of tectonic elements of different hierarchies.

Differential-normalized electrical measurements (DNEM) have shown their efficiency in petroleum prospecting. The method implies detection of oil and gas deposits from polarization anomalies in haloes around rocks altered under the effect of the hydrocarbon pool. Polarization. in the geoelectric section is determined layer-by-layer using space and time derivatives of the TEM process and differential-normalized parameters.

We have studied the main factors that effect consolidation of terrigenous rocks. The porosity of mudstones of the Nepa Formation (Siberian Platform) is shown to reflect the maximum pressures under which the rocks existed throughout their geologic history. It can be used for regional paleotectonic analysis. The porosity of sandstones depends on much more factors operating both on sedimentogenesis and on subsequent catagenesis of the rocks; the major factors are the depths of the maximum burial of sediments, the size of mineral grains, and the intensity and time of secondary cementation of rocks.

The data derived from the monitoring of the electromagnetic field created by an artificial source, which was conducted for years on the eastern Lake Baikal coast, are presented. Twelve observation points are spaced 1 to 40 km apart. One of the points was located on the far coast of Lake Baikal. Measurements have been made every day, The depth of the controlled parts of the Earth's crust does nor exceed 2 to 3 km. Long-term series of the apparent resistivity, meteorological parameters, and water level in Lake Baikal were studied with the help of multivariate analysis software. The electrical conductivity of the uppermost crust is shown to be virtually independent of the water level, atmospheric pressure, and air temperature. The canonical coherence of the multivariate: time series of the apparent resistivities is shown to increase before higher seismicity periods in the Baikal rift zone. An increase in the coherence precedes earthquakes of an energy class of 15 and higher at epicentral distances of up to 650 km. Anomalous effects in the aggregated signal of the multivariate time series of the apparent resistivities, associated with earthquakes of energy classes of 12 and 13, were also revealed at epicentral distances of up to 40 km. As the number of channels increases, the resolution of the aggregated signal also increases, and anomalous features of the signal are recognized at longer epicentral distances. The anomalies of the canonical coherence and aggregated signal may serve as precursors of strong earthquakes in the Baikal rift zone.

The technique, interpretation algorithms, and some results of long (since 1968) tectonomagnetic monitoring in the central part of the Baikal Rift Zone are considered. Today precisional geomagnetic observations are performed at 7 stationary and 280 ordinary stations. In the region of the Ust'-Selenga basin 3-4-year periods of the increased amplitudes of tectonomagnetic anomalies have been revealed (1969-72, 1979-82, and 1991-93), which evidences more quick and intense stress changes in the Earth's crust in these years. This is confirmed by the occurrence of strong earthquakes (M greater than or equal to 5) in these periods, It is noted that such periods of seismotectonic activity repeat roughly every 11 years. The causes of the lower amplitudes of tectonomagnetic anomalies in the BRZ, compared with the Central-Asian regions, are discussed. The possible mechanisms of magnetic-field changes depending on the seasonal variations in the Baikal water level are considered. Interpreting tectonomagnetic anomalies permitted a quantitative estimation of stress changes at the final stage of an earthquake preparation, which are in most cases no more than 0.5-1 determined. This permitted timely revealing the MPa. Some tectonomagnetic criteria of an intermediate-time forecast of earthquakes with M greater than or equal to 5 have been preparation of earthquake in the delta of the Selenga River (13 July 1993, M = 5) - eight months before it.