V. V. Adushkin

Near-surface geophysics: Complex investigations of the lithosphere-atmosphere interactions

The key trends and problems in the study of interactions between the geospheres in the near-surface areas of the continental crust of the Earth which are of most interest for the formation of living environment are formulated. The main periodicities in the variations of geophysical fields determining the natural environmental rhythms are determined. The interactions and transformations of geophysical fields (electric field in the ground and in the atmosphere, radon emanation field, and the field of microseismic vibrations) are considered. It is noted that the tectonic discontinuities and weak disturbances in the solid Earth such as lunar-solar tides and variations in the atmospheric pressure play an important role in the formation of the regimes of geophysical fields at the boundary of the Earth’s crust and the atmosphere. The synchronous instrumental observations reveal a mutual influence and significant correlation between the amplitude variations of geophysical fields of different nature.

Effects of lunar-solar tides in the variations of geophysical fields at the boundary between the Earth’s crust and the atmosphere

Extraterrestrial forcing of natural environmental processes by gravitational interaction between the Sun, the Moon, and the Earth is considered. Based on the instrumental data, the main periodical components and cycles are identified in the time variations of some geophysical fields at the boundary between the Earth’s crust and the atmosphere. Correlation analysis shows that the lunar-solar tides are the key factor responsible for diurnal and quasi-biweekly variations in the ground electric field, radon emanation, water level in wells, and microseismic vibrations. The tidal influence on the various-scale movements of the blocks of the Earth’s crust is analyzed. In the context of the vertical, lateral, and rotational motion of crustal blocks, which is very important for the platforms, a new, precession-like type of displacements is revealed. These movements develop as a result of the nonsynchronous tidal responses of the block and the adjacent interblock gaps or tectonic structures whose strength and strain properties are different in different directions.

Mikhnevo: from seismic station no. 1 to a modern geophysical observatory

The Mikhnevo seismic station was founded in accordance with directive no. 1134 RS of the Council of Ministers of the Soviet Union of February 6, 1954. The station, installed south of Moscow, began its operations on monitoring nuclear tests in the United States and England in 1954. For dozens of years this station was the leading experimental base for elaborating new technical solutions and methods for monitoring nuclear explosions, equipped with modern seismological instruments. At present, the focus of activities has been moved from military applications to fundamental geophysical research. The station preserves its leading position in seismological observations due to the development of national high-performance digital instruments and creation of the small-aperture seismic array, the only one in the central part of European Russia, which is capable of recording weak seismic events with ML ≥ 1.5 within a distance of 100 km.

Blasting-induced seismicity in the European part of Russia

The paper focuses on the increasing contribution of blasting operations to the energy balance of seismic processes. Although the progress in blasting technologies will not produce energy outputs that exceed the energy of natural earthquakes on a global scale, it is shown that in some cases, the regional contribution to seismic energy release by blasting operations is by a few orders of magnitude higher than the energy released by natural earthquakes. In particular, this is valid for the European part of Russia, which is characterized by reasonably weak natural seismic activity. In order to identify the sources of natural seismicity over the European territory of Russia, we present the classification of the industrial blasting operations. The spatial distribution of explosive activities is presented; the consumption of explosives is estimated; and the technology of short-delay mass explosions, which might be helpful for interpretation of seismic records, is described. Zoning the territory of the European part of Russia in terms of the release rate of seismic energy and the peak local magnitudes observed during blasting operations is carried out. It is shown that the hazard level associated with blasting activities does not exceed the corresponding parameters of seismic zoning.The results presented in this paper will probably be useful for solving an important question of seismological studies: is the recorded seismic event a blast or earthquake?

Parameters determining the portion of energy radiated during dynamic unloading of a section of rock massif

Presented are the main results of laboratory experiments aimed at studing the regularities of transition of the cumulated deformation energy to the kinetic one when a block exhibits stick-slip along model fracture filled with geomaterials with different properties. It was shown that even a small variation of material composition of the fault principal slip zone may result in a significant variation of the portion of seismic energy radiated during dynamic unloading of the enclosing rock massif.

Modern Geodynamically Active Zones in the Central East European Craton

To identify the modern geodynamic processes in the structures of the East European Craton (EEC), the complex approach is used. The results of visual and automated deciphering of the LANDSAT satellite images are analyzed combined with the data of preci� sion measurements for horizontal components of motion rates of GPS reference points. The approach used allowed us to consider the modern activity of geo� logical structures and to distinguish the zones of higher geodynamic instability. To analyze the morphostructures and geodynamic setting of the studied territory, we constructed a space� tectonic scheme of the central EEC using the LESSA software packet [1] and data on the deep structure of the Earth’s crust [2] (Fig. 1). In the scheme, the sys� tems of extended lineaments of different directions are marked; these lineaments shape the integrated struc� tural pattern describing the complex geological evolu� tion of the region. Deep faults in the basement are often expressed on the surface as localized deforma� tions and clustered cracking zones. The rheological properties of sedimentary rocks predetermine the “scatter” of boundaries (faults) between the basement blocks [3]. The orientation of extended lineaments and linea� ment forms in the central EEC reflects the block struc� ture of the basement and partially reveals the buried structures that were activated at the neotectonic stage. Figure 1 shows that the major lineaments are oriented in the SW–NE and SE–NW directions and are related with the primary regmatic division of the crust trans� formed by tectonic processes. Sublatitudinal and sub� meridional lineaments are of secondary value [4]. The distinguished extended Moscow–Ryazan lineament zone of SE–NW strike consists of a series of subparal� lel extended lineaments and corresponds to the transi� tion zone boundary at the layer of sedimentary cover

Application of a three-component seismic array to improve the detection efficiency of seismic events by the matched filter method

It is found that the best results, in terms of the efficiency of detecting regional seismic phases from blast sources, are achieved by using the method of waveform cross correlation applied to the data from a small-aperture array of three-component sensors

Detection of ultraweak signals on the Mikhnevo small-aperture seismic array by using cross-correlation of waveforms

Original Russian Text

Radiative forcing of aerosols in Central Asia

137 In this work, we present the results of investigations that characterize the role and radiation effects of small scale aerosol over the region of Central Asia. Fine dispersed particles fundamentally influence the climate and biosphere owing to their influence on the distribution of solar energy over the surface of the Earth [1–3]. They decrease the solar irradiance by absorption and reflection before it reaches the surface and cause distortions in the temperature, precipita tion, and biomass production cycles. Absorption leads to the heating of the atmosphere. Fine dispersed par ticles initiate condensation in the clouds. An increase in the number of drops in a cloud intensifies the sun light reflection effect (makes clouds brighter), which also leads to darkening and cooling of the surface.

Response of the seismic background to geomagnetic variations

642 The interaction and transformation of geophysical fields in the surface regions of the Earth’s crust is of special interest for distinguishing the nature and mechanisms of intergeospheric interactions and determining the influence of the geophysical field on the environment [1, 2]. The field of natural seismic oscillations of the Earth’s crust reflecting the degree of stability of its specific parts (for example, active facture zones, mobility of the block system, etc.) has become one of the most important fields in the human engi neering activity that contains information about the time variability of the geodynamic state of the Earth’s crust [3, 4]. This is the reason why it is important to distinguish the possible links between the background seismic field and other geophysical fields necessary for recognition of the interaction and transformation mechanisms. In this work, we analyze the influence of pulse geomagnetic perturbations on the field of back ground seismic oscillations in the Earth’s crust. A quantitative relation between the amplitude of pulse geomagnetic variations and fluctuations in the velocity of oscillations in the Earth’s seismic background in specific conditions was obtained for the first time.