Results 1 - 10 of 250
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[en] The spatial features of the aftershock sequences triggered by three moderate magnitude events with coda-duration magnitudes 4.1, 5.1 and 5.6, which occurred in Northeastern Italy and Western Slovenia, were investigated. The fractal dimension and the orientations of the planar features fitting the hypocentral data have been inferred. The spatial organization is articulated through two temporal phases. The first phase is characterized by the decreasing of the fractal dimension and by vertically oriented planes fitting the hypocentral foci. The second phase is marked by an increase of the fractal dimension and by the activation of different planes, with more widespread orientation. The aftershock temporal distribution is analysed with a model based on a static fatigue process. The process is favoured by the decrease of the overburden pressure, the sharp variations of the mechanical properties of the medium and the unclamping effect resulting from positive normal stress changes caused by the mainshock stress step.
[en] The report provides an assessment of the route for the SNF Fuel transport system from the K Basins to the CVDF and to the CSB. Results include the identification of any underground structures or utilities traveled over by the transport, the overburden depths for all locations identified, evaluation of the loading conditions, and determination of the effects of the loads on the structures and utilities
[en] A search for diffuse neutrinos with energies in excess of 105 GeV is conducted with AMANDA-II data recorded between 2000 and 2002. Above 107 GeV, the Earth is essentially opaque to neutrinos. This fact, combined with the limited overburden of the AMANDA-II detector (roughly 1.5 km), concentrates these ultra high-energy neutrinos at the horizon. The primary background for this analysis is bundles of downgoing, high-energy muons from the interaction of cosmic rays in the atmosphere. No statistically significant excess above the expected background is seen in the data, and an upper limit is set on the diffuse all-flavor neutrino flux of E2 Φ90%CL < 2.7 x 10-7 GeV cm-2s-1 sr-1 valid over the energy range of 2 x 105 GeV to 109 GeV. A number of models which predict neutrino fluxes from active galactic nuclei are excluded at the 90% confidence level
[en] The Modane Underground Laboratory, with an overburden of 4800 m.w.e, offers an excellent site for experiments requiring a low-background environment. The laboratory is currently hosting experiments in particle and astroparticle physics and low-level germanium gamma-ray spectrometry activities. This paper sketches the main characteristics, scientific activities and facilities of the laboratory as well as its insertion in the European program ILIAS. Special emphasis is given to the description of the low radioactivity measurements and Germanium detectors
[en] Newly emerging building materials, such as concrete hollow block and aerated concrete, is currently general wall construction materials. Radon exhalation from concrete hollow block, cement mortar and aerated concrete was measured through experiment under the same environmental conditions. The impacts of cement mortar overburden on radon exhalation rate from construction materials were evaluated and comparison of radon exhalation rates from different materials was made. This can provide data for the choice of construction materials in aspects of prevention and reduction of radon. (authors)
[en] We investigate the surface thermophysical properties (thermal emissivity, thermal inertia, roughness fraction and geometric albedo) of asteroid (99942) Apophis, using the currently available mid-infrared observations from CanariCam on Gran Telescopio CANARIAS and far-infrared data from PACS on Herschel, based on the Advanced Thermophysical Model. We show that the thermal emissivity of Apophis should be wavelength dependent from 8.70 μm to 160 μm, and the maximum emissivity may appear around 20 μm, similar to that of Vesta. Moreover, we further derive the thermal inertia, roughness fraction, geometric albedo and effective diameter of Apophis within a possible 1 scale of , , and , and 3 scale of , , and . The derived low thermal inertia but high roughness fraction may imply that Apophis could have regolith on its surface, where stronger space weathering but weaker regolith migration has happened in comparison with asteroid Itokawa. Our results show that small-size asteroids could also have fine regolith on the surface, and further infer that Apophis may have been delivered from the Main Belt by the Yarkovsky effect. (paper)
[en] The ALEPH detector at LEP has been used to measure the momentum spectrum and charge ratio of vertical cosmic ray muons underground. The sea-level cosmic ray muon spectrum for momenta up to 2.5 TeV/c has been obtained by correcting for the overburden of 320 meter water equivalent (mwe). The results are compared with Monte Carlo models for air shower development in the atmosphere. From the analysis of the spectrum the total flux and the spectral index of the cosmic ray primaries is inferred. The charge ratio suggests a dominantly light composition of cosmic ray primaries with energies up to 1015 eV.
[en] Full text: We know that in some cases the processes of oil and gas development is followed by variations in bardic drive and fluid saturation in the formation, and thus, variations in reservoir-rock properties may take place. The present paper deals with some effects that appear in reservoirs at the development process. Being at natural occurrence conditions the reservoir rocks are influenced by effective pressure. The above pressure is a difference of overburden and formation pressures. The variation of formation pressure results in effective pressure increase, and this, in its turn may result in deformation processes in the formation
[en] Coseismic folds induced by blind thrust faults have been observed in many earthquake zones, and they have received widespread attention from geologists and geophysicists. Numerous studies have been conducted regarding fold kinematics; however, few have studied fold dynamics quantitatively. In this paper, we establish a conceptual model with a thrust fault zone and tectonic stress load to study the factors that affect coseismic folds and their formation mechanisms using the finite element method. The numerical results show that the fault dip angle is a key factor that controls folding. The greater the dip angle is, the steeper the fold slope. The second most important factor is the overburden thickness. The thicker the overburden is, the more gradual the fold. In this case, folds are difficult to identify in field surveys. Therefore, if a fold can be easily identified with the naked eye, the overburden is likely shallow. The least important factors are the mechanical parameters of the overburden. The larger the Young’s modulus of the overburden is, the smaller the displacement of the fold and the fold slope. Strong horizontal compression and vertical extension in the overburden near the fault zone are the main mechanisms that form coseismic folds.