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Some attempts of polarimetric sounding of Comet Halley will be undertaken from the flyby probes. In order to facilitate the final planning and the future interpretation of these experiments we have done a thorough analysis of practically all available polarimetric observations. An emphasis is made on interpretation attempts and their discussion. The results of the phase dependence of polarization investigations are presented covering a wide range of phase angles . The chief peculiarities of this dependence are: maximum polarization at = 90, diminishing through zero at 20, negative values up to several per cent and a final growth to zero at zero . A division into gaseous and dusty comets on polarimetric basis is revealed. The wavelength dependence of polarization is discussed. The numerous results of detailed polarimetry are compared to the negative results of attempts to detect the elliptical polarization. New observational problems arising from the evidence given by the negative polarization at small phase angles and by the opposition effect recently discovered are discussed. 相似文献
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Shevchenko V. I. Guseva T. V. Dobrovolsky I. P. Krupennikova I. S. Lukk A. A. 《Izvestiya Atmospheric and Oceanic Physics》2018,54(8):826-847
Izvestiya, Atmospheric and Oceanic Physics - The tectonic structure, seismicity, and modern geodynamics of the roughly EW-trending Pyrenees are considered based on the literature data. Geological... 相似文献
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Subhorizontal compressive stresses and deformations play a leading role in the formation of the tectonic structure of mobile belts. These stresses and deformations can arise due to either a lateral convergence of lithospheric plates, subplates, and other lithospheric units or an increase in the volume of layered rocks between fixed walls. Results of geodetic measurements indicate a great role of the latter process. 相似文献
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E.V. Dobrovolsky 《Chemical Geology》1987,60(1-4):89-94
The peculiarities of weathering processes involving duration, slow change of ambient conditions, isothermality as well as proceeding in open systems permit to study these processes in a steady-state approach (dCi/dt = 0, where Ci is concentration of intermediates; and t is time). The most typical quasi-stationary processes for a water-rock system are: (1) non-equilibrium step - surface reaction of primary-mineral dissolution; and (2) non-equilibrium step - secondary-mineral precipitation. These respectively determine two extreme mechanisms of mineral formation: (1) pseudomorphous replacement; and (2) dissolution-transfer-crystallization. Besides non-stationary weathering processes are known. It is the case when a process is controlled by diffusion through a layer of secondary minerals which have been deposited on the surface of the primary mineral. A mathematical model of weathering dynamics of feldspar with its metasomatic replacement by clay minerals is presented. Numerical simulation led to the prediction of mineral zonality development along the weathering profile at any time. 相似文献
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I. P. Dobrovolsky 《Izvestiya Physics of the Solid Earth》2006,42(5):429-433
In the 20th century, observations conducted with the local leveling network of the Garm research area revealed vertical displacements of the Earth’s surface that were considered as precursors of the earthquakes of September 13, 1973 (M = 4.2), and June 9, 1975 (M = 5.2). In this paper, these observations are used to solve inverse problems of the theory of earthquake preparation in relation to the prediction problem. On the basis of such observations immediately before an earthquake, only the location and energy of the forthcoming earthquake could be determined. Results obtained for the stronger earthquake show satisfactory agreement with parameters of the real event. Results for the weaker earthquake are less satisfactory, but the disagreement cannot be regarded as absolutely unacceptable. 相似文献
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Estimation of the size of earthquake preparation zones 总被引：8，自引：0，他引：8
During the earthquake preparation a zone of cracked rocks is formed in the region of a future earthquake focal zone under the influence of tectonic stresses. In the study of the surrounding medium this region may be considered as a solid inclusion with altered moduli. The inclusion appearance causes a redistribution of the stresses accompanied by corresponding deformations. This paper deals with the study of deformations at the Earth's surface, resulting from the appearance of a soft inclusion. The Appendix contains an approximate solution of the problem for a soft elastic inclusion in an elastic half-space. It is assumed that the moduli of the inclusion differ slightly from those of the surrounding medium (by no more than 30%). The solution permits us to calculate the deformations at the Earth's surface for the inclusion with an arbitrary heterogeneity and anisotropy. The problem is solved by the small perturbation method. The calculation is made for a special case of a homogeneous isotropic inclusion where only the shear modulus decreases. The shear stresses act at infinity. The equations are deduced for the estimation of deformations and tilts at the Earth's surface as a function of the magnitude of the preparing earthquake and the distance from the epicentre. Comparison has shown a satisfactory agreement between the theoretical and field results. Let us assume that the zone of effective manifestation of the precursor deformations is a circle with the centre in the epicentre of the preparing earthquake. The radius of this circle called ‘strain radius’ may be calculated from the equation $$\rho = 10^{0.43M} km,$$ where M is the magnitude. It was shown that the precursors of other physical nature fall into this circle. 相似文献
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A. A. Soloviev A. D. Gvishiani A. I. Gorshkov M. N. Dobrovolsky O. V. Novikova 《Izvestiya Physics of the Solid Earth》2014,50(2):151-168
We present the results of verifying the areas that were detected as prone to strong earthquakes by the pattern recognition algorithms in different regions of the world with different levels of seismicity and, therefore, different threshold magnitudes demarcating the strong earthquakes. The analysis is based on the data presented in the catalog of the U.S. National Earthquake Information Center (NEIC) as of August 1, 2012. In each of the regions considered, we examined the locations of the epicenters of the strong earthquakes that occurred in the region after the publication of the corresponding result. There were 91 such earthquakes in total. The epicenters of 79 of these events (87%) fall in the recognized earthquake-prone areas, including 27 epicenters located in the areas where no strong earthquakes had ever been documented up to the time of publication of the result. Our analysis suggests that the results of the recognition of areas prone to strong earthquakes are reliable and that it is reasonable to use these results in the applications associated with the assessment of seismic risks. The comparison of the recognition for California with the analysis of seismicity of this region by the Discrete Perfect Sets (DPS) algorithm demonstrates the agreement between the results obtained by these two different methods. 相似文献
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