Microbarograph

The microbarograph of a new design has been offered, and the general principle of its operation is considered. The microbarograph is distinguished from well-known ones; it incorporates a compensatory spring eliminating a zero-point drift of the measuring spring, two additional springs that upgrade the angular displacement sensitivity of the microbarograph, and a control and calibration block that makes it possible to perform the remote calibration of the microbarograph and to control it.     

Temporal evolution of backward erosion piping in small-scale experiments

Backward erosion piping (BEP) is a form of internal erosion which can lead to failure of levees and dams. Most research focused on the critical head difference at which piping failure occurs. Two aspects have received less attention, namely (1) the temporal evolution of piping and (2) the local hydraulic conditions in the pipe and at the pipe tip. We present small-scale experiments with local pressure measurements in the pipe during equilibrium and pipe progression for different sands and degrees of hydraulic loading. The experiments confirm a positive relation between progression rate and grain size as well as the degree of hydraulic overloading. Furthermore, the analysis of local hydraulic conditions shows that the rate of BEP progression can be better explained by the bed shear stress and sediment transport in the pipe than by the seepage velocity at the pipe tip. The experiments show how different processes contribute to the piping process and these insights provide a first empirical basis for modeling pipe development using coupled seepage-sediment transport equations.

     

Hot dry rocks: An inexhaustible and renewable source of energy

Geological, methodological, and economic aspects of the production and utilization of petrother mal resources (heat of “dry” rocks) for electric energy production and heat supply are considered. Possibility of the utilization of natural fracture zones or artificial fissure zones, which are created by hydraulic fracturing of underground rock massifs, is noted. Application of new tools for drilling deep wells makes the petrochemical energy competitive relative to both other types of renewable resources and traditional organic fuel.     

The earthquake sequence of May 1951 at Jucuapa, El Salvador

Three earthquakes that happened over two days in May 1951 caused extensive damage to villages in a small area of eastern El Salvador (Central America). Contemporary hypocentral solutions indicated focal depths, confirmed by re-calculations using available seismic data, of the order of 90 km, suggesting events associated with the subducted Cocos plate. Macroseismic observations strongly indicate that the earthquakes were of very shallow focus and this is supported by wave-form modeling and the appearance of seismograms recorded in Guatemala. A re-evaluation of the location and source characteristics for these events is presented, together with a fault plane solution and additional macroseismic evidence. The implications for seismic hazard and risk assessment in Central America, where shallow earthquakes of moderate magnitude, frequently occurring in clusters, pose the greatest threat to settlements which, like the area affected by these events, are concentrated along the axis of Quaternary volcanoes.     

Application of laser strainmenters to the study of earthquake physics

The paper considers possibilities of applying laser strainmeters for the study of earthquake physics. One of laser strainmeters is described. A high efficiency of using the laser strainmeters for the study of earthquakes and their precursors is shown. In records of the spaced laser strainmeters, anomalous deformations propagating from the east to the west with the speed comparable with that of migration of earthquakes were found.     

Comparative toxicities of chlorinated biphenyls on sea urchin egg fertilisation and embryogenesis

The aim of this study was to compare the biological actions of selected chlorinated biphenyls (CB's) (with different degrees of chlorine substitution), using the sea urchin test system, for their ability to affect fertilisation, embryogenesis and mitotic activity. Sea urchin embryos were exposed to the test agents throughout larval development or for shorter intervals (e.g. before or after hatching). Sperm or eggs were exposed before fertilisation, thereafter the contaminants were removed from embryo cultures. The results showed maximal activities from medium-chlorinated (tetra- and hexachloro-substituted) compounds, as compared to low- and high-chlorinated biphenyls (mono-, di- and octachloro-substituted), at nominal levels ranging from 10⁻⁶m to 10⁻⁵m. This held true for the different parameters and treatment schedules. Developmental defects were only detected following post hatching exposure of embryos to CB's, whereas pre-hatching exposure failed to reveal any embryological or cytogenetic abnormalities.     

Explosion breccias of the Vysokogorskoe tin–porphyry deposit: Genesis and role in ore formation (Kavalerovo ore district,Primorye)

Detailed geological observations and analytical studies make it possible to distinguish two groups of fluid-explosion breccias (FEB) in the Vysokogorskoe tin deposit of the Kavalerovo ore district. These breccias are assumed to be related to different stages of geological (geodynamic) evolution and played different roles in ore formation. The earlier breccias (79–69 Ma), which were altered by boron metasomatism and subsequent main tin mineralization, were most probably formed at the Cretaceous subduction stage. The later breccias (55–51 Ma) are syngenetic to the dacite (rhyolite) porphyry dikes of the Paleocene–Eocene transform stage. They were formed after precipitation of the majority of the cassiterite, but prior to the latest quartz–fluorite–carbonate stage of ore formation. According to the Sillitoe classification, the explosion breccias of the Vysokogorskoe deposit correspond to a magmatic–hydrothermal genetic type. They are characterized by multiple brecciation and intersection by small bodies of porphyritic rhyolites.     

Analysis of the reproduction of dynamic processes in the stratosphere using the climate model of the institute of numerical mathematics,Russian academy of sciences

The reproduction of dynamic processes in the stratosphere at extratropical latitudes is considered in calculations of the atmospheric module of the global climate model of the Institute of Numerical Mathematics, Russian Academy of Sciences, with an upper boundary of 0.2 hPa (~60 km) for the period from 1979 to 2008 in comparison with the data observational. Changes in temperature, zonal wind, activity of planetary waves, heat fluxes in the lower stratosphere, and sudden stratospheric warmings with the displacement and splitting of the polar vortex, as well as the distribution of associated circulation anomalies in the troposphere, are analyzed.     

Study of neotectonic activity of morphostructures in the central part of the east european craton by remote sensing methods

The combined approach is used for studying recent tectonic activity in the central part of the East European Craton (EEC).This approach incorporates the methods of automated lineament analysis and satellite geodesy with the conventional geological mapping analysis. The space tectonic map (space image based) is reconstructed, and morphostructures that are active at the recent and present tectonic stage are delineated by processing the Landsat image mosaic. The direction and rate of horizontal displacement of crustal blocks, which is caused by deep geodynamical processes, are determined using the GPS data. The study is preliminary since only few GPS stations within the EEC have sufficiently long time series of observations.     

Geometrical focusing as a mechanism for significant amplification of ground motion in sedimentary basins: analytical and numerical study

We study the geometrical and material conditions which lead to focusing of seismic waves traveling across a concave velocity interface representing the boundary of a sedimentary basin within a denser rock. We approximate, using geometrical analysis for plane-waves, the combination of interface eccentricities and velocity ratios for which the seismic rays converge to a near surface region of the basin. 2-D finite difference modeling is used to compute Peak Ground Velocity (PGV) and spectral amplification across the basin. We show that effective geometrical focusing occurs for a narrow set of eccentricities and velocity ratios, where seismic energy is converged to a region of $\pm $ 0.5 km from surface. This mechanism leads to significant amplification of PGV at the center of the basin, up to a factor of 3; frequencies of the modeled spectrum are amplified up to the corner frequency of the source. Finally, we suggest a practical method for evaluating the potential for effective geometrical focusing in sedimentary basins.