The instrumental seismicity of the Barents and Kara sea region: relocated event catalog from early twentieth century to 1989     

Alexey Nikolaevich Morozov  Natalya V. Vaganova  Vladimir E. Asming  Yana V. Konechnaya  Zinaida A. Evtyugina 《Journal of Seismology》2018,22(5):1171-1209

We have relocated seismic events registered within the Barents and Kara sea region from early twentieth century to 1989 with a view to creating a relocated catalog. For the relocation, we collected all available seismic bulletins from the global network using data from the ISC Bulletin (International Seismological Centre), ISC-GEM project (International Seismological Centre–Global Earthquake Model), EuroSeismos project, and by Soviet seismic stations from Geophysical Survey of the Russian Academy of Sciences. The location was performed by applying a modified method of generalized beamforming. We have considered several travel time models and selected one with the best location accuracy for ground truth events. Verification of the modified method and selection of the travel time model were performed using data on four nuclear explosions that occurred in the area of the Novaya Zemlya Archipelago and in the north of the European part of Russia. The modified method and the Barents travel time model provide sufficient accuracy for event location in the region. The relocation procedure was applied to 31 of 36 seismic events registered within the Barents and Kara sea region.  相似文献   

Euxinia as a dominant process during OAE1a (Early Aptian) on the Eastern Russian Platform and during OAE1b (Early Albian) in the Middle Caspian     

Svetlana O. Zorina  Oksana V. Pavlova  Bulat M. Galiullin  Vladimir P. Morozov  Alexey A. Eskin 《中国科学:地球科学(英文版)》2017,60(1):58-70

A detailed study of the mineral composition and microstructure of the black shales associated with OAE1a (Eastern Russian Platform), OAE1b (Middle Caspian), and the host rocks has been carried out using X-ray diffraction, scanning electron microscopic, and microprobe analyses. The results provide important constraints for depositional environments in the sedimentary basins. Black shales with pyrite framboids imply euxinic (sulfidic) conditions with increased organic matter preservation. Disintegrating framboids suggest partial or complete dissolution of the organic matter inside the framboids due to increasing water oxygenation. OAE1a on the Eastern Russian Platform is heterogeneous as it includes thin interbeds of concretionary coccolith limestones within the interval of bituminous shales, and correlates with the Lower Aptian Rhagodiscus angustus nannofossil zone. The coccolith limestones indicate short intermittent episodes of interrupted stagnation, rapid oxygenation, and restoration of normal marine conditions. The presence of montmorillonite, albite, microcline, and diopside in the bituminous siltstones and in the host siltstones of OAE1a on the Eastern Russian Platform, as well as a high content of titanium in the black siltstones correlated with OAE1b in the Middle Caspian allow proposing significant input of pyroclastic material into the extant sea.  相似文献   

Perturbation‐based moveout approximations in anisotropic media          下载免费PDF全文

Shibo Xu  Alexey Stovas  Qi Hao 《Geophysical Prospecting》2017,65(5):1218-1230

The moveout approximations play an important role in seismic data processing. The standard hyperbolic moveout approximation is based on an elliptical background model with two velocities: vertical and normal moveout. We propose a new set of moveout approximations based on a perturbation series in terms of anellipticity parameters using the alternative elliptical background model defined by vertical and horizontal velocities. We start with a transversely isotropic medium with a vertical symmetry axis. Then, we extend this approach to a homogeneous orthorhombic medium. To define the perturbation coefficients for a new background, we solve the eikonal equation with horizontal velocities in transversely isotropic medium with a vertical symmetry axis and orthorhombic media. To stabilise the perturbation series and improve the accuracy, the Shanks transform is applied for all the cases. We select different parameterisations for both velocities and anellipticity parameters for an orthorhombic model. From the comparison in traveltime error, the new moveout approximations result in better accuracy comparing with the standard perturbation‐based methods and other approximations.  相似文献   

A possible mechanism of stimulation of seismic activity by ionizing radiation of solar flares     

Valery M. Sorokin  Alexey K. Yashchenko  Victor A. Novikov 《地震科学（英文版）》2019,32(1):26-34

A possible mechanism of earthquake triggering by ionizing radiation of solar flares is considered. A theoretical model and results of numerical calculations of disturbance of electric field, electric current, and heat release in lithosphere associated with variation of ionosphere conductivity caused by absorption of ionizing radiation of solar flares are presented. A generation of geomagnetic field disturbances in a range of seconds/tens of seconds is possible as a result of large-scale perturbation of a conductivity of the bottom part of ionosphere in horizontal direction in the presence of external electric field. Amplitude-time characteristics of the geomagnetic disturbance depend upon a perturbation of integral conductivity of ionosphere. Depending on relation between integral Hall and Pedersen conductivities of disturbed ionosphere the oscillating and aperiodic modes of magnetic disturbances may be observed. For strong perturbations of the ionosphere conductivities amplitude of pulsations may obtain ~10² nT. In this case the amplitude of horizontal component of electric field on the Earth surface obtains 0.01 mV/m, electric current density in lithosphere –10^–6 A/m², and the power density of heat release produced by the generated current is 10^–7 W/m³. It is shown that the absorption of ionizing radiation of solar flares can result in variations of a density of telluric currents in seismogenic faults comparable with a current density generated in the Earth crust by artificial pulsed power systems (geophysical MHD generator " Pamir-2” and electric pulsed facility " ERGU-600”), which provide regional earthquake triggering and spatiotemporal variation of seismic activity. Therefore, triggering of seismic events is possible not only by man-made pulsed power sources but also by the solar flares. The obtained results may be a physical basis for a novel approach to solve the problem of short-term earthquake prediction based on electromagnetic triggering phenomena.  相似文献   

Isotopic composition of gas hydrates in subsurface sediments from offshore Sakhalin Island, Sea of Okhotsk   总被引：1，自引：1，他引：0  

Akihiro Hachikubo  Alexey Krylov  Hirotoshi Sakagami  Hirotsugu Minami  Yutaka Nunokawa  Hitoshi Shoji  Tatiana Matveeva  Young K. Jin  Anatoly Obzhirov 《Geo-Marine Letters》2010,30(3-4):313-319

Hydrate-bearing sediment cores were retrieved from recently discovered seepage sites located offshore Sakhalin Island in the Sea of Okhotsk. We obtained samples of natural gas hydrates and dissolved gas in pore water using a headspace gas method for determining their molecular and isotopic compositions. Molecular composition ratios C₁/_C2+ from all the seepage sites were in the range of 1,500–50,000, while δ¹³C and δD values of methane ranged from ?66.0 to ?63.2‰ VPDB and ?204.6 to ?196.7‰ VSMOW, respectively. These results indicate that the methane was produced by microbial reduction of CO₂. δ¹³C values of ethane and propane (i.e., ?40.8 to ?27.4‰ VPDB and ?41.3 to ?30.6‰ VPDB, respectively) showed that small amounts of thermogenic gas were mixed with microbial methane. We also analyzed the isotopic difference between hydrate-bound and dissolved gases, and discovered that the magnitude by which the δD hydrate gas was smaller than that of dissolved gas was in the range 4.3–16.6‰, while there were no differences in δ¹³C values. Based on isotopic fractionation of guest gas during the formation of gas hydrate, we conclude that the current gas in the pore water is the source of the gas hydrate at the VNIIOkeangeologia and Giselle Flare sites, but not the source of the gas hydrate at the Hieroglyph and KOPRI sites.  相似文献   

中蒙俄高铁建设的影响机理及对策   总被引：1，自引：1，他引：0  

董锁成  杨洋  李富佳  程昊  李静楠  BILGAEV Alexey  李泽红  李宇 《地理学报》2019,74(2):297-311

中蒙俄高铁建设是促进中蒙俄交通基础设施互联互通、打造国际陆上交通走廊的重要举措,是中蒙俄经济走廊建设的重要突破口。科学合理地布局中蒙俄高铁线路、规避高铁建设面临的不利影响和风险,急需理清高铁建设的影响因子,揭示其作用机理和空间分布格局,制定针对性强的防控对策。本文分析了中蒙俄高铁建设的主要影响因子,阐明了各类因子对高铁建设的影响机理,通过构建一种综合集成的影响指数评估模型（IIIEM）,量化评估了不同地区各类影响因子的影响指数,揭示了其空间分布格局,并据此制定了消除影响的中蒙俄高铁东线和西线的线路布局建议方案。提出通过“高铁换资源、高铁换市场”等互利共赢创新合作模式,消除经济影响;加强沟通和技术展示,降低社会影响;通过设置缓冲区及高科技手段,规避生态风险;构建中蒙俄跨境地区三大生态风险跨国联合防控体系,加强政策对接,促进中蒙俄经济一体化等防控对策及保障措施。本研究将为中蒙俄高铁建设线路科学合理布局、风险防控提供科技支撑和决策参考。  相似文献   

Reindeer Herders Without Reindeer. The Challenges of Joint Knowledge Production on Kolguev Island in the Russian Arctic     

Alexey O. Pristupa  Machiel Lamers  Maria Tysiachniouk  Bas Amelung 《社会与自然资源》2019,32(3):338-356

Kolguev Island in the Russian Arctic has a unique tundra ecosystem and an indigenous Nenets population whose livelihood is traditionally based on reindeer herding. The Nenets faced a major crisis in 2013–2014 when the reindeer population collapsed. Widely different explanations for this collapse were put forward. This lack of a shared perspective points at the failure of genuine joint knowledge production (JKP) in the island’s UNEP–GEF’s ECORA project (2004–2009). The ECORA project aimed to achieve integrated ecosystem management by stimulating dialog and mutual learning among indigenous people, state agencies, and scientists. This paper analyses the failure of ECORA’s JKP, using a recently developed framework of conditions for successful JKP. The results suggest that ECORA met none of these conditions. It failed at bringing the scientific and indigenous knowledge systems together, and the produced knowledge did not resonate with indigenous people’s perception of living in Kolguev.  相似文献   

The evolution of eccentricity in the eclipsing binary system AS Camelopardalis     

Valentina Kozyreva  Anatoly Kusakin  Alexey Bogomazov 《天文和天体物理学研究(英文版)》2018,(1)

In 2002,2004 and 2017 we conducted high precision CCD photometry observations of the eclipsing binary system AS Cam.By analysis of the light curves from 1967 to 2017(our data + data from the literature) we obtained photometric elements of the system and found a change in the system's orbital eccentricity of ?e = 0.03 ± 0.01.This change can indicate that there is a third companion in the system in a highly inclined orbit with respect to the orbital plane of the central binary,and its gravitational influence may cause the discrepancy between observed and theoretical apsidal motion rates of AS Cam.  相似文献   

Taphonomic phenomenon of ancient hair from Glacial Beringia: perspectives for palaeoecological reconstructions          下载免费PDF全文

Irina V. Kirillova  Johannes van der Plicht  Stanislav V. Gubin  Oksana G. Zanina  Olga F. Chernova  Elena G. Lapteva  Svetlana S. Trofimova  Eugeny V. Zinovyev  Anton A. Zharov  Elena O. Fadeeva  Thijs Van Kolfschoten  Fedor K. Shidlovskiy  Alexey A. Kotov 《Boreas: An International Journal of Quaternary Research》2016,45(3):455-469

An accumulation of mammoth hair, discovered in the Bol'shaya Chukochya River valley (northeast Yakutia, Russia), was found to contain remains of terrestrial and aquatic organisms, including plants, insects, crustaceans, birds and mammals. Radiocarbon dating indicated that this post‐mortem taphocoenosis represented multiple time periods. The mammoth hair was dated to older than 45 ka BP, the plants were dated to 12 750±50 a BP (which corresponds to a shift in the environmental conditions and landscapes during the formation of thermokarst in northeastern Russia) and the bird feathers were dated to 4115±40 a BP. A scenario of the formation of this fossil assemblage is proposed, covering the MIS 3‐1 time range. The hair also yielded various Arctic branchiopod crustaceans, which inhabit shallow temporary water bodies and therefore are important for reconstruction of palaeoenvironments. The cladoceran subgenus Daphnia (Ctenodaphnia), currently absent from the Asian part of Beringia, is reported from this region for the first time. The study demonstrates that the discovered permafrost‐preserved hair is a unique repository of Ice Age organisms.  相似文献   

Another Record: Ocean Warming Continues through 2021 despite La Ni?a Conditions     

Lijing CHENG  John ABRAHAM  Kevin E. TRENBERTH  John FASULLO  Tim BOYER  Michael E. MANN  Jiang ZHU  Fan WANG  Ricardo LOCARNINI  Yuanlong LI  Bin ZHANG  Zhetao TAN  Fujiang YU  Liying WAN  Xingrong CHEN  Xiangzhou SONG  Yulong LIU  Franco RESEGHETTI  Simona SIMONCELLI  Viktor GOURETSKI  Gengxin CHEN  Alexey MISHONOV  Jim REAGAN 《大气科学进展》2022,39(3):373-385

The increased concentration of greenhouse gases in the atmosphere from human activities traps heat within the climate system and increases ocean heat content (O...  相似文献