Collisional processes at the junction of the Aleutian–Kamchatka arcs: new evidence from fission track analysis and field observations     

Ralf Freitag  Christoph Gaedicke  Boris Baranov  & Nikolay Tsukanov 《地学学报》2001,13(6):433-442

The Aleutian island arc collides with the Kuril–Kamchatka arc in the area of the Cape Kamchatka peninsula. Field studies of neotectonic structures and apatite fission track analysis provide evidence for crustal plate shortening onshore the Cape Kamchatka peninsula. Tectonic blocks show differential mean exhumation rates varying from 0.18 ± 0.04 mm yr⁻¹ in the north up to 1.2 ± 0.18 mm yr⁻¹ in the south of the peninsula. A few of the fission track length data point to an unsteady exhumation rate. The blocks are separated by major dextral fault zones splaying off from Aleutian island arc fault zones. Across the western segment of the North American–Pacific Plate boundary the strain is partitioned along the fault zones and increases from north to south. Results from this study suggest that indentation and accretion of island arc fragments has recently occurred in the southeastern part of the Cape Kamchatka peninsula.  相似文献   

Man-and-machine technology for the prediction of mineral deposits using geophysical data     

Boris S. Bysigin 《Mathematical Geology》1992,24(6):711-717

To predict secondary geological structures that control the localization of mineral deposits in areas of cover, it is practical to use complex geophysical data. The prediction process is iterative and employs pattern recognition techniques. Each iterative cycle can include the procedure of location and ranging according to their appropriateness to the problem. The quality of the prediction is a function of the suitability of the geological environment under investigation and of the anomalies contained in the geophysical data and their selection.  相似文献   

Quasi-static Motions of Viscoelastic Satellites     

Boris S. Bardin  Andrzej J. Maciejewski 《Celestial Mechanics and Dynamical Astronomy》2001,81(1-2):51-56

We consider the motion of a spacecraft which consists of a rigid body with a thin viscoelastic circular ring attached at some point of the body. Assuming that the stiffness of the ring is large and the dissipation is small enough, we study the quasi-static motion which is set in after free elastic oscillations have damped. In particular, the steady-state motions in the weakly elliptic orbit are found and their stability is investigated.  相似文献   

On the Normal-Incidence Reflection Coefficient in Porous Media     

Carcione  José M.  Gei  Davide  Gurevich  Boris  Ba  Jing 《Surveys in Geophysics》2021,42(4):923-942

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Engineering Geological Map of the Sakha （Yakutia） Republic     

Vladimir B. Spektor  Yaroslav I. Torgovkin  Alena A. Shestakov  Valentin V. Spektor  Lena D. Ivanov  Boris M. Kozmin 《寒旱区科学》2014,6(5):0484-0493

The Engineering Geological Map of the Sakha（Yakutia） Republic covers about 3 million kilometers which is one-fifth of the territory of Russia.The map displays ground and geocryological conditions and active faults.Seismic intensity,schemes of zoning by factors of engineering geological conditions,and the general scheme of engineering geological zoning of the Sakha（Yakutia） Republic or the SR（Y）,are shown on the inset maps.The map is required to provide information for planning,construction and exploitation of engineering structures in the SR（Y）.A distinguishing feature of the map is the indication of almost blanket distribution of the frozen ground class.Types of the frozen ground class are separated by lithology,while ground varieties are separated by temperature.Fresh and ultra-fresh suprapermafrost water is predominant within the territory.The compiled map indicates parts of the Arctic-Asian and Baikalo-Stanovoi planetary seismic belts that make engineering geological conditions more complicated.  相似文献   

Quantitative estimates of temperature and precipitation changes over the last millennium from pollen and lake-level data at Lake Joux, Swiss Jura Mountains     

Michel Magny  Odile Peyron  Boris Vannière  Bruno Vermot-Desroches 《Quaternary Research》2011,75(1):45-54

This paper presents quantitative climate estimates for the last millennium, using a multi-proxy approach with pollen and lake-level data from Lake Joux (Swiss Jura Mountains). The climate reconstruction, based on the Modern Analogue Technique, indicates warmer and drier conditions during the Medieval Warm Period (MWP). MWP was preceded by a short-lived cold humid event around AD 1060, and followed by a rapid return around AD 1400 to cooler and wetter conditions which generally characterize the Little Ice Age (LIA). Around AD 1450 (solar Spörer minimum), the LIA attained a temperature minimum and a summer precipitation maximum. The solar Maunder minimum around AD 1690 corresponded at Joux to rather mild temperatures but maximal annual precipitation. These results generally agree with other records from neighbouring Alpine regions. However, there are differences in the timing of the LIA temperature minimum depending on the proxy and/or the method used for the reconstruction. As a working hypothesis, the hydrological signal associated with the MWP and LIA oscillations at Lake Joux may have been mainly driven by a shift around AD 1400 from positive to negative NAO modes in response to variations in solar irradiance possibly coupled with changes in the Atlantic meridional overturning circulation.  相似文献   

GeoWeb and crisis management: issues and perspectives of volunteered geographic information   总被引：3，自引：0，他引：3  

Stephane Roche  Eliane Propeck-Zimmermann  Boris Mericskay 《GeoJournal》2013,78(1):21-40

Mapping, and more generally geopositioning, has become ubiquitous on the Internet. This democratization of geomatics through the GeoWeb results in the emergence of a new form of mapping based on Web 2.0 technologies. Described as Web-mapping 2.0, it is especially characterized by high interactivity and geolocation-based contents generated by users. A series of recent events (hurricanes, earthquakes, pandemics) have urged the development of numerous mapping Web applications intended to provide information to the public, and encourage their contribution to support crisis management. This new way to produce and spread geographic information in times of crisis brings up many questions and new potentials with regard to urgency services, Non Governmental Organisations (NGO), as well as individuals. This paper aims at putting into perspective the development of GeoWeb, both in terms of technologies and applications, against crisis management processes.  相似文献   

Vanishing capillarity solutions of Buckley–Leverett equation with gravity in two-rocks’ medium     

Boris Andreianov  Clément Cancès 《Computational Geosciences》2013,17(3):551-572

For the hyperbolic conservation laws with discontinuous-flux function, there may exist several consistent notions of entropy solutions; the difference between them lies in the choice of the coupling across the flux discontinuity interface. In the context of Buckley–Leverett equations, each notion of solution is uniquely determined by the choice of a “connection,” which is the unique stationary solution that takes the form of an under-compressive shock at the interface. To select the appropriate connection, following Kaasschieter (Comput Geosci 3(1):23–48, 1999), we use the parabolic model with small parameter that accounts for capillary effects. While it has been recognized in Cancès (Networks Het Media 5(3):635–647, 2010) that the “optimal” connection and the “barrier” connection may appear at the vanishing capillarity limit, we show that the intermediate connections can be relevant and the right notion of solution depends on the physical configuration. In particular, we stress the fact that the “optimal” entropy condition is not always the appropriate one (contrarily to the erroneous interpretation of Kaasschieter’s results which is sometimes encountered in the literature). We give a simple procedure that permits to determine the appropriate connection in terms of the flux profiles and capillary pressure profiles present in the model. This information is used to construct a finite volume numerical method for the Buckley–Leverett equation with interface coupling that retains information from the vanishing capillarity model. We support the theoretical result with numerical examples that illustrate the high efficiency of the algorithm.  相似文献   

Formation of a White-Light Jet Within a Quadrupolar Magnetic Configuration     

Boris Filippov  Serge Koutchmy  Ehsan Tavabi 《Solar physics》2013,283(1):143-156

The cadence and resolution of solar images have been increasing dramatically with the launch of new spacecraft such as STEREO and SDO. This increase in data volume provides new opportunities for solar researchers, but the efficient processing and analysis of these data create new challenges. We introduce a fuzzy-based solar feature-detection system in this article. The proposed system processes SDO/AIA images using fuzzy rules to detect coronal holes and active regions. This system is fast and it can handle different size images. It is tested on six months of solar data (1 October 2010 to 31 March 2011) to generate filling factors (ratio of area of solar feature to area of rest of the solar disc) for active regions and coronal holes. These filling factors are then compared to SDO/EVE/ESP irradiance measurements. The correlation between active-region filling factors and irradiance measurements is found to be very high, which has encouraged us to design a time-series prediction system using Radial Basis Function Networks to predict ESP irradiance measurements from our generated filling factors.  相似文献   

Impact airblast triggers dust avalanches on Mars     

Kaylan J. Burleigh  Henry J. Melosh  Livio L. Tornabene  Boris Ivanov  Alfred S. McEwen  Ingrid J. Daubar 《Icarus》2012,217(1):194-201

Visible images from the Mars Reconnaissance Orbiter have revealed more than 200 new impact sites on Mars (almost all in dust-mantled regions) containing 1–50 m diameter craters, often in clusters. We count approximately 65,000 small-scale slope streaks within 2 to 3 km of one such cluster and categorize them into four morphologically distinct types. Here we show that these slope streaks (interpreted as dust avalanches) are triggered by the impact event but, surprisingly, are not due to seismic shaking; instead, the dust avalanches are due to airblasts created by the supersonic meteor(s) before impact. Sixteen of the new impact sites are associated with high areal densities of dust avalanches. The observed dust avalanche frequency suggests that impact-generated airblasts constitute a locally important and previously unrecognized process for inducing slope degradation on Mars.  相似文献