Electron paramagnetic resonance (EPR) spectra and the magnetic susceptibility are measured in 44 samples of bottom deposits of the Akademicheskii submarine ridge, Lake Baikal. The EPR spectral amplitude I, magnetic susceptibility chi, and chemical composition of the samples are shown experience significant irregular variations with depth. The variations in X and I have synchronous maximums at a variable period of 50-100 cm; the susceptibility variations are characterized by the values chi(max) = 939 x 10(-6) SI units, chi(min) = 202 x 10(-6) SI units, and chi(av) = 548 x 10(-6) SI units. The variations in the composition of rock-forming elements fit into a scheme of simple mixing of two independent constant sources of sedimentary material: products of provenance areas and silica of eolian transport. The magnetic properties of the samples are mainly controlled by microphases containing Fe3+, ions of the goethite type that do not belong to the provenance material, and the process of their formation is inversely correlated with the silica supplied into the reservoir: maximum values of chi and I invariably correlate with a minimum Si concentration. Samples similar in chemical composition exhibit significant variations in chi and I, indicating a high sensitivity to the temperature of formation of magnetic particles. Their content and sizes have higher values at relatively low temperatures.

We report results from a GPS network installed following special criteria in the framework of an international project and implications for recent crustal movements in the western Altai-Sayan region. The network includes one permanent (NVSK, near Novosibirsk) and 17 campaign sites resurveyed yearly in the Altai mountains and their northern surroundings. The sites were operated with three Trimble 4700 GPS receivers and hard-mounted antennas at geodetic marks, in 2-3 day sessions at each site. The experience of seasonal and permanent monitoring along the similar to76 km Talaya-Irkutsk baseline was used to analyze some methodological issues of GPS measurements.

The formation temperature below the sea or lake floor is frequently measured with a sensor probe that is inserted into the unconsolidated sediment, and the thermal conductivity of sediment is measured in situ with an independent heating experiment. Friction during the insertion raises the temperature of a probe. This paper presents the method and the test results of using the cooling history of friction-heated probes for the determination of equilibrium formation temperature and thermal conductivity. The inverse modelling (IM) for the desired parameters is formulated together with the finite-element simulation of the cooling history. The starting parameter values for IM are generated with a genetic algorithm (GA) that searches for them in the likely parameter ranges. The IM is constrained in an objective function by a commonly used asymptotic relation between the declining temperature and the inverse time. In addition to satisfying the root-mean-square misfit, the results are assessed by the equality between the model conductivity and the conductivity obtained through the asymptotic relation and by how well the models can predict the cooling behaviour at time beyond the record period for IM. The results of testing synthetic data with random noise up to +/-0.005 K and twenty 8-11 min long data sets from four sites in Lake Baikal indicate that the desired parameters can be determined from the first 2.5 min of the cooling records. By comparison with independent measurements or through repeated GA-IM, equilibrium temperatures can be consistently determined to within 0.002 K and thermal properties typically to +/-5 per cent. The method has also been successfully applied to seven sets of 5 min long data sets at one marine heat flow station.

The paper presents analysis of seismotectonic strain associated with the aftershocks of the 19 August 1992 M = 7.3 Suusamyr earthquake. Surface rupturing produced by the main shock falls into the zone of maximum uniform strain. The earthquake caused reorientation of strees axes on the ends of the major rupture was accompanied by rift-type aftershocks. The nearly horizontal N-S orientation of the principal P-axis remained invariable and that of the T-axis changed 25 years before the main shock and during the aftershock and post-aftershock activity, which is consistent with the trend of maximum regional compression.

A geoelectric model of the Chuya basin has been constructed on the basis of an extensive collection of TEM data obtained In the 1970-80s. The experimental data were interpreted by solving inverse problems using the ERA and SONET computer systems. The modeling imaged the deep structure of the basin and provided a more exact idea of the thickness of its Cenozoic fill. Moreover, it revealed main features of the regional seismicity pattern.

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.

Measurements performed by means of tiltmeters and expansometers in special-purpose underground observatories are important part of the research of the crustal kinematic parameters in the northern Tien Shan. Long runs of tilts and deformations observed at the Ala-Archa underground station (42.63 degrees N, 74.50 degrees E) have been analyzed. Results of tidal analysis are reported. Slow variations in tilts and deformations reveal seasonal changes and slope effects caused by seismic activity of the region. The annual average rate of meridional compression was 3 . 10(-7) for the period 1985-97 and 7 . 10(-7) for 1989-97.

The Messoyakha gas field has long been considered a world unique field where gas is extracted from natural gas hydrates. At the same time, this idea has been based solely on implicit evidence. The present study addresses the problem of the gas-hydrate-bearing capacity of the field proceeding from data on its gas production geology and temperature measurements in boreholes and from long-term (1981-97) observations of variability of gas composition.The Cenomanian productive beds of the Messoyakha field are remarkable for their inhomogeneity. Extraction of gas chiefly from the lower portion of the productive beds has caused a descending gas flow from the upper beds, which is marked by negative temperature anomalies observed during logging of abandoned wells. The conditions within the anomalies are favorable for the formation of gas hydrates related to gas extraction. Repeated analyses of PT-conditions in the field showed that they are favorable for gas formation only in the upper strata, and thus the available PT-data do not allow us to be positive about the gas-hydrate-bearing capacity of the field. We have attempted to estimate this capacity on the basis of gas geochemistry using 3000 analyses for helium, 100 analyses for hydrocarbons, carbon dioxide, and nitrogen, 23 analyses for argon, and eight analyses far all rare gases. During that work we based upon the fact that a number of gas components (primarily helium) do not form hydrates and thus should accumulate in the coexisting gas.Helium concentrations in the Messoyakha field showed to be strongly variable, which might be caused by the hydrate process, including the effects of the field operation. Data on the variability of gas composition, especially on helium concentrations, indicate that natural gas hydrates have never existed in the central part of the field (top of the anticline). Natural gases may occur (or may have occurred prior to the field operation) on the periphery of the field, whereas in its central part, in the upper portion of the productive beds, gas hydrates may have formed around the boreholes during gas extraction. We suppose that the quantitative estimation of the gas-hydrate-bearing capacity of the Messoyakha field should be the main focus of further studies.

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.

Geothermal data on six kimberlite provinces of ancient platforms in Siberia, Africa, North America, and South America are considered. The intensity of heat flow there varies from 10-18 to 62-100 mW/m(2), averaging 46-54 mW/m(2). These average values are in concordance with conductive geotherms obtained by thermobarometry of mineral associations from deep-seated xenoliths from kimberlite pipes. The only exclusion is the Yakutian kimberlite province In the east of the Siberran Platform, where the intensity of measured heat flows (20-30 mW/m(2)) is considerably lower than that calculated for the time of kimberlite formation (35-40 mW/m(2)). This anomaly may be related not to the climate cooling but to a decrease in the intensity of radiogenic heat generation in the Earth's crust and shielding of mantle heat now. This is suggested from the occurrence of kimberlite fields within the protrusions of the lower crust with minimum contents of radioactive elements in its rocks.

A gamma-spectroscopic analysis of the upper (to 20 cm) layer of the Teletskoe bottom sediments was carried out immediately at the sites of investigations. A total of 30 sites were studied for Cs-137 distribution throughout the bottom section. The content of Cs-137 varies from 1-5 to 130-140 Bq/kg. Maximum 137Cs concentrations are observed at depths of 2-10 cm. The horizon of the maximum 137Cs contamination is dated to 1963. The horizon dated to 1948 is taken as the upper boundary of the "preatomic" sedimentation period. The known depth and time of formation of these bench marks permitted estimation of the rate of recent (the last 50 years) sedimentation in the Teletskoe basins. On the most part of the lakescape the rate changes by 1-2 mm/year, averaging 1.33 mm/year. The spatial variations in sedimentation rate are governed mainly by the dynamics of the lake waters. The modern resources of buried Cs-137 are estimated at 0.2-0.5 Bq/cm(2) and correlate with the sedimentation rate.

As a result of seismic works carried out by the CDP-reflected wave method on Baikal in 1989-92, seismic boundaries were recognized for the first time for a fresh-water basin in the sedimentary cover, which may be identified with the lower boundary of a methane hydrate layer. Thus, for a considerable part of Baikal the thickness of the gas hydrate layer (its upper boundary coincides with the bottom) is estimated to range from 0 to 350-400 m. Depths of occurrence of the lower boundary of the gas hydrate layer were mapped; then this map was used to estimate an terrestrial heat flow. A technique for the calculation of a heat flow is described in this paper. Along with typical seismic boundaries, the heat flow was estimated from data on depth and temperature of the bottom, from the thermal conductivity of bottom sediments within the gas hydrate layer. The temperature at the lower boundary of the layer was determined from the most known phase diagram of the methane hydrate stability. The number of estimates of heat flow in the central and southern parts of the lake totalled to 480, averaging to 76 mW/m(2) with variations from 58 to 116 mW/m(2). Comparison of calculated and measured values of heat flow shows their general correspondence. At the same time, the seismic data predict a higher and more uniform heat flow, probably, because of its increase with depth. Analysis shows that the calculations are accurate within +/-10 mW/m(2) The study performed is tentative. It is shown that the seismic data can principally be used for estimation of thermal regime of bottom sediments of the Baikal basin.