Radial profile of sunspot magnetic field on the SDO data     

I. Zhivanovich  A. A. Solov’ev  V. V. Smirnova  A. Riehokainen  V. G. Nagnibeda 《Astrophysics and Space Science》2016,361(3):102

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Freshening of near-bottom waters in Lake Baikal triggered by the Mw6.2 Kultuk earthquake of August 2008     

Nikolay G. Granin  Natalia A. Radziminovich  Liba Z. Granina  Vadim V. Blinov  Ruslan Y. Gnatovskiy 《Geo-Marine Letters》2012,32(5-6):453-464

In September 2008, freshening of near-bottom water and an increase in concentration of suspended particles were observed in the western part of southern Lake Baikal. The reduction in the content of total dissolved solids was about 0.4–0.7?mg/kg (0.7?%), and average suspended particle concentration increased strongly to 6–9?mg/l, the background value being 0.2?mg/l. The spatial distribution of these waters was virtually identical to the focal area of the M_w6.2 Kultuk earthquake that occurred on 27 August 2008. It is suggested that there was a causal relationship between these two phenomena. Freshening of a significant amount (about 20?km³) of near-bottom waters was plausibly caused by an input of poorly mineralized pore waters from bottom sediments as a result of dissociation of methane gas hydrates suspected to occur in the area. The energy radiated by the earthquake source was four orders of magnitude smaller than that needed to explain the observed freshening of near-bottom waters. This points to other mechanisms leading to seismic-induced sediment failure and possible subsequent hydrate dissociation in the case of the Kultuk earthquake.  相似文献   

Sand dune migration as a factor of geoheritage loss: Evidence from the Siwa Oasis (Egypt) and implications for geoheritage management     

Kholoud M. AbdelMaksoud  Wael M. Al-Metwaly  Dmitry A. Ruban  Natalia N. Yashalova 《Proceedings of the Geologists' Association. Geologists' Association》2019,130(5):599-608

Anthropogenic damage of geoheritage is documented widely, but natural processes can also lead to geoheritage loss. For instance, sand dune migration causes submergence of unique geological and palaeontological sites in desert environments of the Sahara. The Siwa Oasis in the Western Desert of Egypt boasts rich geoheritage, which is represented in many localities. Three of them in the southern part of the oasis are outcrops of highly-fossiliferous limestones. Palaeontological, sedimentary, palaeogeographical, and geomorphological types of geoheritage are recognized there. Sand dune activity on the study area is registered both visually and with remote sensing techniques. Denudation and destruction of naturally-exposed rocks is documented. Evidence of outcrop submergence with sand is found in all cases. The localities are situated in the pathway of rapid (up to ?10 m/yr) dune migration. One locality may disappear within one–two years. Sand dune migration has to be considered as a factor of geoheritage loss in the Siwa Oasis, and the relevant protection of the studied localities is necessary. Geopark creation and improvement of water use in the oasis can also help significantly, as well as the reference to archaeological experience of excavation and protection of heritage sites submerged by sands. More generally, geoheritage conservation should be integrated with a program for sustainable oasis development.  相似文献   

High-pressure single-crystal X-ray diffraction and synchrotron Mössbauer study of monoclinic ferrosilite     

Natalia V. Solomatova  Ayya Alieva  Gregory J. Finkelstein  Wolfgang Sturhahn  Michael B. Baker  Christine M. Beavers  Jiyong Zhao  Thomas S. Toellner  Jennifer M. Jackson 《Comptes Rendus Geoscience》2019,351(2-3):129-140

The phase and spin transitions in single-crystal monoclinic ferrosilite, FeSiO₃, were investigated using X-ray diffraction and Mössbauer spectroscopy up to lower-mantle pressures and room temperature in a helium pressure medium. Using single-crystal X-ray diffraction, we measured the equation of state of ferrosilite up to about 43 GPa. We observed a P2₁/c-to-C2/c phase transition between 1.5 and 1.7 GPa and a phase transition from C2/c to a distinct P2₁/c structure between 30 and 34 GPa. With time-domain Mössbauer spectroscopy, we determined the hyperfine parameters of ferrous iron up to 95 GPa. The phase transitions were correlated with discontinuities in Mössbauer spectral features. We observed the onset of high-spin-to-low-spin transitions in the M1 and M2 sites at ～37 GPa and ～74 GPa, respectively. Understanding the electronic structure of iron in a well-characterized single crystal of ferrosilite may help interpret the behavior of iron in complex dense silicate phases.  相似文献   

Pyroclast textural variation as an indicator of eruption column steadiness in andesitic Plinian eruptions at Mt. Ruapehu     

Natalia Pardo  Shane J. Cronin  Heather M. N. Wright  C. Ian Schipper  Ian Smith  Bob Stewart 《Bulletin of Volcanology》2014,76(5):1-19

Hudson is one of the most active volcanoes in the Southern Andes—it had one of the largest eruptions of the 20th century in 1991 (VEI?=?5) and smaller eruptions in 1971 (VEI?=?3), maybe 1973, and 2011 (VEI of 1-2). We use satellite-based interferometric synthetic aperture radar (InSAR) and thermal imagery to characterize the activity of Hudson between 2004 and 2011 and during the 2011 eruption. InSAR data show that the volcano inflated between 2004 and 2010 with a maximum change rate of between 2 and 3 cm/yr—about half of the deformation rate observed during a previous deformation episode from 1993–1999. Inversion for an inflating point source suggests magma accumulation beneath the SW part of the caldera at an average depth of 10 km. This inferred source is deeper than both the sources estimated for the magma chamber of the 1991 eruption (from petrology) and for the 1993–1999 deformation event. Also, the deformation from 2004–2010 is centered at a slightly different location and has a smaller volume change than that between 1993–1999—further indicating that there is either a large magma reservoir or several separate ones. While the deformation center is a few km from the eruption location near the caldera rim, the two are possibly linked since the predicted static Coloumb stress changes due to the inferred inflation source would encourage unclamping on potential faults in the caldera rim. We also analize nighttime satellite thermal images from MODIS and ASTER. While MODIS did not show any unambiguous evidence for hot spots, ASTER thermal imagery show that at least four months before the eruption there were locations with temperatures 7–8ºK above background. Lahars observed by helicopter overflights on 4 March 2011 and October 2011 suggest that the hotspots may have been caused by lakes or subglacial melting. There is no InSAR data available for the months immediately preceding the eruption, but the ASTER thermal imagery results may indicate an increase in geothermal activity that could have been used to forecast the eruption.  相似文献   

Hydrology needed to manage droughts: the 2015 European case   总被引：1，自引：0，他引：1       下载免费PDF全文

Henny A.J. Van Lanen  Gregor Laaha  Daniel G. Kingston  Tobias Gauster  Monica Ionita  Jean‐Philippe Vidal  Radek Vlnas  Lena M. Tallaksen  Kerstin Stahl  Jamie Hannaford  Claire Delus  Miriam Fendekova  Luis Mediero  Christel Prudhomme  Ekaterina Rets  Renata J. Romanowicz  Sébastien Gailliez  Wai Kwok Wong  Mary‐Jeanne Adler  Veit Blauhut  Laurie Caillouet  Silvia Chelcea  Natalia Frolova  Lukas Gudmundsson  Martin Hanel  Klaus Haslinger  Maria Kireeva  Marzena Osuch  Eric Sauquet  James H. Stagge  Anne F. Van Loon 《水文研究》2016,30(17):3097-3104

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Bayesian logistic regression for presence-only data     

Fabio Divino  Natalia Golini  Giovanna Jona Lasinio  Antti Penttinen 《Stochastic Environmental Research and Risk Assessment (SERRA)》2015,29(6):1721-1736

Presence-only data are referred to situations in which a censoring mechanism acts on a binary response which can be partially observed only with respect to one outcome, usually denoting the presence of an attribute of interest. A typical example is the recording of species presence in ecological surveys. In this work a Bayesian approach to the analysis of presence-only data based on a two levels scheme is presented. A probability law and a case-control design are combined to handle the double source of uncertainty: one due to censoring and the other one due to sampling. In the paper, through the use of a stratified sampling design with non-overlapping strata, a new formulation of the logistic model for presence-only data is proposed. In particular, the logistic regression with linear predictor is considered. Estimation is carried out with a new Markov Chain Monte Carlo algorithm with data augmentation, which does not require the a priori knowledge of the population prevalence. The performance of the new algorithm is validated by means of extensive simulation experiments using three scenarios and comparison with optimal benchmarks. An application to data existing in literature is reported in order to discuss the model behaviour in real world situations together with the results of an original study on termites occurrences data.  相似文献   

Simulation of Subterahertz Emission from the April 2, 2017 Solar Flare Based on the Multiwavelength Observations     

Morgachev  A. S.  Tsap  Yu. T.  Smirnova  V. V.  Motorina  G. G. 《Geomagnetism and Aeronomy》2018,58(8):1113-1122

Geomagnetism and Aeronomy - Millimeter (93 and 140 GHz) emission of the М6.4 solar flare detected on April 2, 2017 in the NOAA 12644 active region by the RT-7.5 telescope of the Bauman Moscow...  相似文献   

On the Source of Sub-Terahertz Radiation of the Solar Flare on April 2, 2017     

Morgachev  A. S.  Tsap  Yu. T.  Smirnova  V. V.  Motorina  G. G. 《Geomagnetism and Aeronomy》2019,59(8):1114-1120

Geomagnetism and Aeronomy - The study analyzes the millimeter emission of a solar flare on April 2, 2017, observed by the Bauman Moscow State Technical University telescope RT-7.5. Based on the...  相似文献   

A conceptual framework for studying collective reactions to events in location-based social media     

Alexander Dunkel  Gennady Andrienko  Natalia Andrienko  Dirk Burghardt  Eva Hauthal  Ross Purves 《International journal of geographical information science》2019,33(4):780-804

Events are a core concept of spatial information, but location-based social media (LBSM) provide information on reactions to events. Individuals have varied degrees of agency in initiating, reacting to or modifying the course of events, and reactions include observations of occurrence, expressions containing sentiment or emotions, or a call to action. Key characteristics of reactions include referent events and information about who reacted, when, where and how. Collective reactions are composed of multiple individual reactions sharing common referents. They can be characterized according to the following dimensions: spatial, temporal, social, thematic and interlinkage. We present a conceptual framework, which allows characterization and comparison of collective reactions. For a thematically well-defined class of event such as storms, we can explore differences and similarities in collective attribution of meaning across space and time. Other events may have very complex spatio-temporal signatures (e.g. political processes such as Brexit or elections), which can be decomposed into series of individual events (e.g. a temporal window around the result of a vote). The purpose of our framework is to explore ways in which collective reactions to events in LBSM can be described and underpin the development of methods for analysing and understanding collective reactions to events.  相似文献