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Seismic Hazard Estimate at the Iberian Peninsula 总被引：1，自引：0，他引：1
—?Seismic hazard at the Iberian Peninsula has been evaluated by using a methodology which combines both zonified and non-zonified probabilistic methods. Seismic sources are used when considering zones where certain calculation parameters may be considered homogeneous, as in zonified methods, while, on the other hand, earthquakes are considered wherever it has taken place, as in non-zonified methods. The methodology which is applied in this paper has been originally used to calculate the seismic hazard maps in the United States. In our case, it has been necessary to adapt the method to the specific features of the seismicity in the Iberian Peninsula and its geographical surroundings, not only with respect to its distribution and characteristics, but also with respect to the properties of the seismic catalog used.¶Geographically, the main feature of the result is the fact that it reflects both historical seismicity and current seismic clusters of the region. Despite the smoothing, maps show marked differences between several seismic zones; these differences becoming more noticeable as exposure time increases. Maximum seismic hazard is found to be in the southwestern region of the Peninsula, especially in the area of the Cape St. Vicent, and around Lisbon. The uncertainty of the results, without considering that due to the attenuation laws, as deduced from the other evaluation parameters, is quite stable, being more sensitive to the parameters b and m max of the Gutenberg-Richter relation. 相似文献
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Using alternative independent variables in lieu of time has important advantages when propagating the partial derivatives of the trajectory. This paper focuses on spacecraft relative motion, but the concepts presented here can be extended to any problem involving the variational equations of orbital motion. A usual approach for modeling the relative dynamics is to evaluate how the reference orbit changes when modifying the initial conditions slightly. But when the time is a mere dependent variable, changes in the initial conditions will result in changes in time as well: a time delay between the reference and the neighbor solution will appear. The theory of asynchronous relative motion shows how the time delay can be corrected to recover the physical sense of the solution and, more importantly, how this correction can be used to improve significantly the accuracy of the linear solutions to relative motion found in the literature. As an example, an improved version of the Clohessy-Wiltshire (CW) solution is presented explicitly. The correcting terms are extremely compact, and the solution proves more accurate than the second and even third order CW equations for long propagations. The application to the elliptic case is also discussed. The theory is not restricted to Keplerian orbits, as it holds under any perturbation. To prove this statement, two examples of realistic trajectories are presented: a pair of spacecraft orbiting the Earth and perturbed by a realistic force model; and two probes describing a quasi-periodic orbit in the Jupiter-Europa system subject to third-body perturbations. The numerical examples show that the new theory yields reductions in the propagation error of several orders of magnitude, both in position and velocity, when compared to the linear approach. 相似文献
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Seismicity pattern of the Betic Cordillera(southern Spain) derived from the fractal properties of earthquakes and faults 
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下载免费PDF全文 Several studies on earthquake occurrence and associated faulting have demonstrated that both phenomena have a scale-invariant behavior which can be analyzed by means of a set of non-integer dimensions(Dq) describing their fractal properties and the calculation of multi-fractal spectra.It is the case that the behavior of these spectra is asymptotic at the ends of the variation interval of q,which is a real number that enters into the definition of the partition function of the dataset.The difference between the extreme values,called multi-fractal spectrum slope,is used to investigate the heterogeneity of the spatial distribution of earthquakes and fault systems.In this paper we focus on the Betic Cordillera,southeastern Spain,which is commonly considered the contact between the Eurasian and African plates and has an important seismic activity in the context of the Iberian Peninsula.Some of the most conspicuous Iberian earthquakes,such as the 1829 mb6.3 Torrevieja and the 1884 mb6.1 Alhama de Granada earthquakes occurred in this mountain range and both reached intensity X.The present work implies a new analysis based on the slope of multi-fractal spectra and referred to the historical seismicity of the region,specifically b-value(frequency distribution of earthquakes respect to magnitude),epicentral location,seismic energy and faulting.On this basis we propose a seismotectonic zonation that is contrasted with the stress state and the geodynamical evolution of the Betic Cordillera. 相似文献
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Petra Hájková Michal Horsák Michal Hájek Adam Lacina Hana Buchtová Barbora Pelánková 《Boreas: An International Journal of Quaternary Research》2012,41(4):690-706
Calcareous fens are unique environments whose history is almost unexplored. The radiocarbon dates of the basal layers of 49 undisturbed calcareous fens showed that in the Western Carpathians (central Europe) many of the extant fen sites originated fairly recently, with two peaks in the High Middle and Roman Ages, the former corresponding to human‐induced changes of the landscape. Conspicuous number of fens also appeared in the Lateglacial and later in the Bronze Age owing to suitable environmental conditions. The Lateglacial calcareous fens were of semi‐open character with coniferous trees, a heliophilous understorey, and mollusc communities composed of several snail species typical of glacial landscapes. We found wood of Taxus baccata in six localities between 7390 and 600 cal. a BP, suggesting that calcareous fens could have represented a refugial habitat for this red‐listed species during the middle Holocene. Using plant macrofossil and mollusc analyses of three representative profiles we illustrate the most common developmental types: (i) fens originating in the Lateglacial, having an open or semi‐open character during the whole Holocene; (ii) open fens originating as wooded wetlands; and (iii) open fens starting their development de novo in the late Holocene. Human activities were responsible for the formation of a high number of calcareous fens, especially in the Outer Western Carpathians, and became important drivers of fen biodiversity development. Only a few recently existing calcareous fens contain old sequences of calcareous deposits. They represent unique natural archives and harbour highly endangered relic populations of fen specialists, making their strict protection urgent. 相似文献
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Jesús Peláez José Manuel Hedo Pedro Rodríguez de Andrés 《Celestial Mechanics and Dynamical Astronomy》2007,97(2):131-150
The special perturbation method considered in this paper combines simplicity of computer implementation, speed and precision, and can propagate the orbit
of any material particle. The paper describes the evolution of some orbital elements based in Euler parameters, which are
constants in the unperturbed problem, but which evolve in the time scale imposed by the perturbation. The variation of parameters
technique is used to develop expressions for the derivatives of seven elements for the general case, which includes any type
of perturbation. These basic differential equations are slightly modified by introducing one additional equation for the time,
reaching a total order of eight. The method was developed in the Grupo de Dinámica de Tethers (GDT) of the UPM, as a tool for dynamic simulations of tethers. However, it can be used in any other field and with any kind of
orbit and perturbation. It is free of singularities related to small inclination and/or eccentricity. The use of Euler parameters
makes it robust. The perturbation forces are handled in a very simple way: the method requires their components in the orbital
frame or in an inertial frame. A comparison with other schemes is performed in the paper to show the good performance of the
method. 相似文献
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The particularly well developed reef-type cyclical sedimentation seen in the Givetian stage of the Dinant synclinorium (Belgium), is discussed in detail with respect to the various facies, their faunal and physicochemical characteristics and their sequence. More recent (Upper Aptian) reef phenomena in the Province of Santander in northern Spain are similar to the Givetian complex (except for their more marked dolomitization) in that they have the same sequence of identical facies and, generally speaking, the same cyclical sedimentation. A comparative study underscores the similarity of environment between the two stages. This environment, during the Upper Aptian, facilitated the deposition of lead-zinc ores at Reocin, which are limited to certain dolomitized reef levels. A close relationship thus emerges between reefs, the process of dolomitization and stratiform ore deposits. 相似文献
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Ch. Leinert U. Graser F. Przygodda L.B.F.M. Waters G. Perrin W. Jaffe B. Lopez E.J. Bakker A. Böhm O. Chesneau W.D. Cotton S. Damstra J. de Jong A.W. Glazenborg-Kluttig B. Grimm H. Hanenburg W. Laun R. Lenzen S. Ligori R.J. Mathar J. Meisner S. Morel W. Morr U. Neumann J.-W. Pel P. Schuller R.-R. Rohloff B. Stecklum C. Storz O. von der Lühe K. Wagner 《Astrophysics and Space Science》2003,286(1-2):73-83
After more than five years of preparation, the mid-infrared interferometric instrument MIDI has been transported to Paranal
where it will undergo testing and commissioning on theVery Large Telescope Interferometer VLTI from the end of 2002through
large part of this year 2003. Thereafter it will be available as a user instrument to perform interferometric observations
over the8 μm–13 μm wavelength range, with a spatial resolution of typically 20 milliarcsec, a spectral resolution of up to
250, and an anticipated point source sensitivity of N = 3–4 mag or 1–2.5 Jy for self –fringe tracking, which will be the only
observing mode during the first months of operation. We describe the layout of the instrument, laboratory tests, and expected
performance, both for broadband and spectrally resolved observing modes. We also briefly outline the planned guaranteed time
observations.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Giulio Baù Claudio Bombardelli Jesús Peláez 《Celestial Mechanics and Dynamical Astronomy》2013,116(1):53-78
A formulation of the perturbed two-body problem that relies on a new set of orbital elements is presented. The proposed method represents a generalization of the special perturbation method published by Peláez et al. (Celest Mech Dyn Astron 97(2):131–150, 2007) for the case of a perturbing force that is partially or totally derivable from a potential. We accomplish this result by employing a generalized Sundman time transformation in the framework of the projective decomposition, which is a known approach for transforming the two-body problem into a set of linear and regular differential equations of motion. Numerical tests, carried out with examples extensively used in the literature, show the remarkable improvement of the performance of the new method for different kinds of perturbations and eccentricities. In particular, one notable result is that the quadratic dependence of the position error on the time-like argument exhibited by Peláez’s method for near-circular motion under the $J_{2}$ perturbation is transformed into linear. Moreover, the method reveals to be competitive with two very popular element methods derived from the Kustaanheimo-Stiefel and Sperling-Burdet regularizations. 相似文献