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81.
Yu. F. Kopnichev I. N. Sokolova K. N. Sokolov 《Izvestiya Physics of the Solid Earth》2013,49(6):786-795
The characteristics of the attenuation field of short-period shear waves in the region of Nevada nuclear test site (NNTS) are studied. The seismograms of underground nuclear explosions (UNEs) and earthquakes recorded by three seismic stations in 1975–2012 at the epicentral distances of up to 1000 km are processed by the methods based on the analysis of the amplitude ratios of Sn to Pn and Lg to Pg waves, as well as the S-coda envelopes for close events. It is shown that the structure of the attenuation field in the Earth’s crust and upper mantle in the NNTS region experienced significant temporal variations during the interval of nuclear operations. The strongest variations were associated with UNEs conducted in the Pahute Mesa area, which held about two-thirds of the most intense explosions. Our data indicate that temporal variations in the structure of the attenuation field are related to the migration of deep fluids. A comparison of the general characteristics of the attenuation field in the regions of the three large nuclear test sites is presented. 相似文献
82.
Generalized geothermal data was used to produce two electronic atlases for Asian Russia,Geothermal Atlas of Siberia（GAS）（1995-2000） and Geothermal Atlas for Siberia and Russian Far East（GASRFE）（2009-2012）.The atlases include heat flow maps,temperatures at depths of 0.5,1,2,3,5 km and lower boundary of permafrost.Quantitative values of parameters are presented as isolines（GAS） and symbols（GASRFE）.GAS website is located at the Trofimuk Institute（www.ipgg.sbras.ru/ru/institute/structure/geophysics/natural-fields）.GASRFE provides the most complete geothermal data on Asian Russia,which has been growing for the last 50 years,and is published on the Internet at http：//maps.nrcgit.ru/geoterm.In this atlas,data about the depth of permafrost lower boundary（ ＂zero＂ isotherm） are presented for the first time. 相似文献
83.
We examine the theoretical and applied aspects related to the concept of the ecological potential of vegetation as an important factor for pursuing of the public environmental policy. Taking into consideration the ecological potential in the nature management system is essential. A map fragment illustrating the ecological potential of the Baikal region is provided. 相似文献
84.
85.
Cosmic gamma-ray burst spectroscopy 总被引：1，自引：0，他引：1
E. P. Mazets S. V. Golenetskii V. N. Ilyinskii Yu. A. Guryan R. L. Aptekar V. N. Panov I. A. Sokolov Z. Ya. Sokolova T. V. Kharitonova 《Astrophysics and Space Science》1982,82(2):261-282
A review is given of the gamma-ray burst energy spectrum measurements on Venera 11 and Venera 12 space probes. The gamma burst continuum approximates in shape thermal brems-strahlung emission of a hot plasma. The radiation temperature varies over a broad range, 50–1000 keV, for different events. Spectra of many bursts contain cyclotron absorption and/or redshifted annihilation lines. Strong variability is typically observed in both continuum and line spectra. These spectral data provide convincing evidence for the gamma-ray bursts being generated by neutron stars with superstrong magnetic fields 1012–1013 G. 相似文献
86.
We bring up the issue related to the need and importance of undertaking an assessment of the present status of vegetation in Prebaikalia. The vegetation of this region has long been experiencing strong anthropogenic destructions, especially in the southern, more developed, areas. Anthropogenic impacts on vegetation continue to be enhanced thus influencing the processes of spontaneous development of vegetation and decreasing its ecological potential. Assessment of the present status of vegetation as a complex self-evolving autotrophic natural entity having its own evolutionary history of development and dynamical potential is used in reference to identifying and evaluating the degree of disturbance of its native (spontaneous) florocenotic structure. To improve objectivity of research results uses a cartographic method supported by GIS technologies. On the basis of the principles of a structural-dynamical classification of plant communities as suggested by V. B. Sochava, we compiled a universal geobotanical medium-scale (1:500 000) map for Prebaikalia. The map was generated for two purposes: inventory, i.e. identifying the typological belonging of existing plant communities in the region, and for assessment–dynamical purpose to identify the epitaxon structure of the entire vegetation cover. These efforts were accompanied by a formalized assessment of the age structure of tree stands of the region’s forest communities as well as a clear differentiation between forest and non-forest vegetation by identifying new burns and felling areas. The findings formed the basis for generating a detailed 1:500 000 map of disturbances to Prebaikalia’s vegetation displaying 11 kinds of vegetation disturbances ranging from the persisting native communities to those substituted by agrocenoses and introductions of urban settlements. A general outline of the present status of vegetation is provided as well as the main directions for nature management optimization in the region within the framework of the state ecological policy. 相似文献
87.
This paper presents a study of ongonites from the Chechek and Akhmirovo dike belts located within the Kalba—Narym batholith in Eastern Kazakhstan. The obtained conclusions are based on the investigations of melt and fluid inclusion in quartz phenocrysts, supplemented by mineralogical and geochemical data. It was established that the dike rocks were formed by crystallization of volatile-rich rare-metal melts in the presence of an aqueous fluid phase with subordinate amounts of carbon dioxide and methane. The ongonites crystallized from three geochemically different melts. Porphyritic phenocrysts in the ongonites of the Chechek and Akhmirovo dike belts crystallized at close temperatures 560–605°C and pressure of 3.6–5.3 kbar. Ongonite magmas that formed the Chechek and Akhmirovo dike belts had a high ore potential. However, degassing dynamics was not favorable for the development of metasomatism and formation of hydrothermal mineralization at the level of dike emplacement. The area of the rare-metal magmatism represented by ongonite dikes and rare-metal granite pegmatites has been distinguished in the northern part of the Kalba—Narym zone. The formation of rare-metal magmas was related to the differentiation in large granitoid chambers under the effect of juvenile fluids derived from the Tarim mantle plume. 相似文献
88.
Records of deep-focus Hindu Kush earthquakes in the depth ranges 70–110 and 190–230 km made by 45 digital and analogue seismic stations were analyzed to study the attenuation field of short period seismic waves in the lithosphere of central Tien Shan. The dynamic characteristics studied include the ratio of peak amplitudes in S and P waves (S/P) and the ratio of the S-wave maximum to the coda level in the range t = 400 ± 5 s, where t is the lapse time (S/c400) for 1.25 Hz. Comparatively high values of S/P are shown to prevail in most of the area, corresponding to lower S-wave attenuation. Upon this background is a band of high and intermediate attenuation in the west of the area extending along the Talas-Fergana fault in the south and afterwards turning north-northeast. The rupture areas of the two largest (M ≥ 7.0) earthquakes which have occurred in Tien Shan during the last 25 years are confined to this band. Abnormally high values of S/c400 were obtained for stations situated in the rupture zone of the August 19, 1992, magnitude 7.3 Suusamyr earthquake and around it. For two of the stations we found considerable time variations in the coda envelope before the earthquake. The effective Q was derived from compressional and shear wave data for the entire area, as well as for the band of high attenuation. Comparison with previous data shows that the attenuation field in the area has changed appreciably during 20–25 years, which can only be due to a rearrangement of the fluid field in the crust and uppermost mantle. It is hypothesized that a large earthquake is very likely to occur in the northern part of the attenuating band. 相似文献
89.
Seismicity characteristics in the areas of Sarez Lake and the Nurek water reservoir are studied. Ring-shaped seismicity structures in two depth ranges (0–33 and 34–70 km) formed prior to the Pamir earthquake of December 7, 2015 (M w = 7.2). Seismicity rings cross each other near the Usoi Dam, which formed after the strong earthquake in 1911 and led to the formation of Sarez Lake, and near the epicenter of the Pamir earthquake. In addition, three out of the four strongest events (М ≥ 6.0) recorded in the Pamir region at depths of more than 70 km since 1950 have occurred near Sarez Lake. An aggregate of the data allows us to conclude that the Pamir earthquake, despite its very large energy, refers to events related to induced seismicity. Ring-shaped seismicity structures in two depth ranges also formed in the Nurek water reservoir area. It is supposed that the formation of ring-shaped structures is related to the self-organization processes of a geological system, which result in the ascent of deep-seated fluids. In this respect, the lithosphere is gradually adapting to the additional load related to the filling of the water reservoir. The difference between Nurek Dam (and many other hydroelectric power stations as well) and Usoi Dam is the permanent vibration in the former case due to water falling from a height of more than 200 m. Such an effect can lead to gradual stress dissipation, resulting in the occurrence of much weaker events when compared to the Pamir earthquake of December 7, 2015, in the areas of artificial water reservoirs. 相似文献
90.
Yu. F. Kopnichev D. D. Gordienko I. N. Sokolova 《Journal of Volcanology and Seismology》2009,3(1):44-58
This paper deals with characteristics of the short period S-wave attenuation field in the rupture zones of 37 large and great earthquakes with M s = 7.0–8.6, as well as in low seismicity areas. We estimate the effective quality factor from Sn and Lg coda envelopes in two time intervals (Q 1 and Q 2). The quantity Q 1 is a measure of shear wave attenuation in the uppermost mantle, at depths of down to approximately 200–250 km, while Q 2 is relevant to deeper horizons of the upper mantle. We studied variations in the attenuation field in the rupture zone of the 1950 Assam earthquake. We examined the parameters Q 1, Q 2, and Q 1/Q 2 as functions of the time ΔT elapsed after a large earthquake. It is shown that the parameter Q 2 in rupture zones is practically independent of ΔT, while the quantities Q 1 and Q 1/Q 2 increase until ΔT ～ 20–25 years, especially rapidly for normal, normal-oblique, and strike-slip earthquake mechanisms. This analysis provides evidence that, as ΔT increases, so does the quality factor in the upper mantle for shear waves. It is supposed that this is related to the rise of mantle fluids to the crust. Geodynamic mechanisms are discussed that can support a comparatively rapid “drying” of the upper mantle beneath earthquake rupture zones. 相似文献