Seismic Location Calibration of the European Arctic

—?A crustal velocity model has been developed for Fennoscandia, the Baltic shield and adjacent areas. This model represents a simplified average of various models developed for parts of this region. We show that P-wave travel times calculated with this model provide an excellent fit to observations at the Fennoscandian, KRSC and IRIS station networks for a set of seismic events with known or very well-constrained locations. The station-event paths cover large parts of Western Russia and the Barents Sea, thus indicating that this model, which we denote the Barents model, is appropriate for this entire region. We show by examples that significant improvements in event location precision can be achieved compared to using the IASPEI model. We finally use the Barents model to calculate locations of recent small seismic events in the Novaya Zemlya region of interest in a CTBT monitoring context.     

Assessing the Rate of Dissolved Oxygen Consumption in the Epilimnion of a Stratified Water Body

The results of field studies in the Mozhaisk Reservoir are used to assess variations in the consumption rate of O₂dissolved in water at different patterns of the reservoir hydrological structure.     

The effect of water level variations on production-destruction processes in the Mozhaisk Reservoir

The results of many-year studies of production destruction processes in the Mozhaisk Reservoir are used to examine their specific features in extremely dry years. It is shown that the processes of organic matter formation and destruction in the reservoir are more active when water level is low. Variations in the intensity of production-destruction processes in all phases of synoptic cycle are analyzed (during cooling, cold, heating, and warm). Changes in weather conditions are shown to be accompanied by phytocenosis restructuring. Fine-cell phytoplankton forms are shown to dominate in phytocenosis composition when water level in the reservoir is extremely low.     

Dynamics of Phosphorus and Balance Estimate of Its Exchange Processes with the Bed in the Mozhaisk Reservoir during Vegetation Period

Data of complex offshore observations were used to analyze variations in the concentrations of mineral and organic phosphorus in the epilimnion and hypolimnion of the Mozhaisk Reservoir within the vegetation period. Vertical phosphorus fluxes at the hypolimnion boundaries were assessed by using the balance method with allowance made for the phosphorus transformations in the water mass within the vegetation periods considered. Destruction processes were found to proceed most intensely during the moderate blooming of phytoplankton, when these processes facilitate the formation of anaerobic conditions in hypolimnion, whereas exchange processes intensify abruptly in the periods of intense phytoplankton blooming and during its decline.     

Assessment of the oxygen consumption rate in the water column for the Mozhaisk and Ivankovo reservoirs

Long-term studies of oxygen consumption rate in the water column of the Mozhaisk and Ivankovo reservoirs enabled the calculation of statistical dependencies of oxygen consumption rate on oxygen deficit, taking into account the trophic level and hydrological structure of the water column. On the basis of the values of oxygen deficit, the vertical distribution of water density, and water transparency, the oxygen consumption rate in the water column can be estimated.     

Induced seismicity in the Khibiny Massif (Kola Peninsula)

The topic of this paper is to review recent processes of increasing seismic activity in the Khibiny Massif in the Kcla Peninsula. It is a typical example of induced seismicity caused by rock deformation due to the extraction of more than 2·10⁹ tons of rock mass since the mid-1960s. The dependence of seismic activity on the amount of extracted ore is demonstrated. Some of the induced earthquakes coincide with large mining explosions, thus indicating a trigger mechanism. The largest earthquake, which occurred on 16 April 1989 (M _L= 4.1) could be traced along the surface for 1200 m and observed to a depth of at least 220 m. The maximum measured displacement was 15–20 cm.     

Sedimentation of suspension in the Mozhaisk Reservoir

Sedimentation fluxes of suspension were determined in experimental studies on the Mozhaiskoe Reservoir in summer. The leading factors of formation and the rate of accumulation of sedimentary material and organic mater in the reservoir in different phases of synoptic cycle in the channel and shallow zones of the bed in the central part of the reservoir.     

Influence of intrareservoir and meteorological factors on the rate of oxygen demand by valley reservoir sediments

Analyzed are the spatial and temporal variations of the sediment oxygen demand rate in the Mozhaisk Reservoir. It is demonstrated that this rate in summer depends both on the sediment characteristics and on the biological and meteorological factors. It is revealed that the content of labile organic substances in the silt is of great importance for the oxygen consumption rate (all other factors being equal). The inflow of these substances to the bottom is regulated by the water column stratification depending considerably on weather conditions. Estimated is the contribution of main organic matter consumers in the bottom sediments.     

On Seasonal Alternation of Priority Factors that Control the Rate of Oxygen Consumption by Soils in a Valley-Type Reservoir

Data of long-term studies are used to evaluate the rate of O₂ consumption by soils in the Mozhaisk Reservoir as a function of a number of physicochemical and biological factors. Seasonal variations in the rate of O₂ consumption by the soils and the relationship between these variations and the priority factors are established.     

On the role of hydrometeorological factors in formation of the valley-type reservoir anoxic zone

Based on the multiyear researches of the Mozhaisk reservoir oxygen regime and methods of mathematical modeling, dependence of the anoxic zone formation rate on the hydrometeorological factors was studied. These factors define a degree of the water mass stratification and intensity of the production and degradation processes and, hence, the anoxia development rate.