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21.
Felix Borleanu Mihaela Popa Mircea Radulian Johannes Schweitzer 《Journal of Seismology》2011,15(3):431-442
The BURAR seismic array, located in Northern Romania (Bucovina region), is designed to monitor events located in an area poorly
covered by other existing seismic stations. In order to use the BURAR array for single-station locations, it is crucial to
calibrate the azimuth and slowness parameters, which are currently used in array techniques to locate earthquakes, blasts
or nuclear explosions. The goal of this study is to apply “f–k” and plane wave fit techniques in order to constrain the slowness
and azimuth parameters at BURAR for teleseismic, regional and local events. The analysis was carried out using P and S waves
recorded for events occurred between 2004 and 2008 within a radius of 50° around BURAR. The azimuth values obtained applying
both methods strongly deviated from the theoretical values for regions like Central Turkey, Bulgaria, Dodecanese Islands and
other parts of Greece, while the ray parameter deviations with respect to a 1-D IASP91 reference model are less significant.
For the local events, the anomalies are smaller, except the particular case of Vrancea intermediate-depth earthquakes for
which strong azimuth deviations (33.5°), both positive and negative, are observed. We investigate how these systematic deviations
in azimuth are explained by the structure lateral heterogeneities which characterize the study region. 相似文献
22.
The systematic analysis of seismograms recorded on the Romanian territory using Vrancea intermediate-depth earthquakes shows a strong asymmetric pattern relative to the epicentral area: on one side, in the Transylvanian Basin and the Eastern Carpathians (approximately along the inner volcanic chain), the amplitudes are reduced by a factor of 20 on average and the high frequencies are attenuated, in contrast with the other side, in the foreland platform. This pattern is explained by a significant attenuation increase caused by a strong lateral variation of the structure in the upper mantle, immediately towards NW of the Vrancea seismic active volume. This region corresponds to the most recent volcanic activity in the Persani Mountains and with the low-velocity body adjacent toward NW to the high-velocity body subducted beneath Vrancea area as indicated by seismic tomography and heat flow results. The CALIXTO'99 tomography experiment, deployed for 6 months in 1999, provides the largest number of observations for Vrancea earthquakes ever recorded on the Romanian territory. We select data from 8 earthquakes generated in this time interval in the Vrancea nest, which were recorded with signal / noise ratio greater than 5 by at least 25 stations. All of them are small- to moderate-magnitude events (3.6 ≤ Mw ≤ 4.2). The attenuation is much more important in the high-frequency range (> 1 Hz), than at low frequencies. Since the large Vrancea earthquakes can radiate significant energy in the low-frequency range (< 1 Hz), our results show that the seismic hazard level is much more uniform all over the Romanian territory in the low-frequency range than in the high-frequency range. 相似文献
23.
The water leakage in the urban areas causes a continuous rise in the water table, with harmful effects. An experimental drainage
system, based on horizontal well technology, was designed and implemented in a populated area. Groundwater flow modeling was
used to assess the hydrodynamic efficiency of the system through drain conductance parameter estimation. 相似文献
24.
The VRANCEA99 and VRANCEA2001 seismic refraction experiments are part of a multidisciplinary project to study the Eastern Carpathians in Romania. The objectives of these studies are intended to disclose a more detailed picture of the crustal and upper mantle structures above the seismically active Vrancea region. In this paper we provide additional constraints for the upper crustal structures of the area. The 1999 campaign consisted of a 320-km-long N–S profile and a 70-km-long E–W profile. The intersecting 2001 profile extended in E–W direction from the Hungarian border to the Black Sea. In order to enhance the model resolution, first arrival data from local crustal earthquakes were also included.This configuration allowed for the first time to derive a 3-D velocity model for the upper crust of the Romanian Carpathian Orogen, within a 115×235 km wide region, centred over the Vrancea seismic zone. The 3-D model reveals lateral velocity variations, which were not visible on the in-line interpretations. It allows us to distinguish between foreland platform areas, foreland basins and the Carpathian Orogen. Clear velocity differences between the foreland basins south and southeast of the Eastern Carpathians and the Focsani Basin further north indicate different pre-Miocene sedimentary compositions and geological evolutions of these foreland platforms. The involved Moesian and Scythian platforms are separated by the Trotus Fault system, which is observed as a velocity discontinuity. An upper crustal high-velocity zone, above the northern Vrancea seismic zone, could also be identified. This high-velocity zone is explained by a Middle Pliocene to Pleistocene E–W oriented out-of-sequence thrust of the crystalline basement, below the decollement of the flysch nappes. 相似文献
25.
26.
Goro Komatsu Gaetano Di Achille Ciprian Popa Stefano Di Lorenzo Jose Alexis Palmero Rodriguez 《Icarus》2009,201(2):474-491
The plains of Aurorae and Ophir in the equatorial region of Mars display geomorphic evidence indicative of extensive but generally short-lived paleohydrological processes. Elaver Vallis in Aurorae Planum south of Ganges Chasma is an outflow channel system >180 km long, and here inferred to have formed by cataclysmic spillover flooding from a paleolake(s) contained in the Morella crater basin. Ganges Cavus is an enormous 5-km-deep depression of probable collapse origin located in the Morella basin. The fluid responsible for the infilling of the Morella basin likely emerged at least partially through Ganges Cavus or its incipient depression, and it may have been supplied also from small-scale springs in the basin. Similar paleohydrological processes are inferred also in Ophir Planum. It is reasonable to assume that water, sometimes sediment-laden and/or mixed with gases, was the responsible fluid for these phenomena although some of the observed features could be explained by non-aqueous processes such as volcanism. Water emergence may have occurred as consequences of ground ice melting or breaching of cryosphere to release water from the underlying hydrosphere. Dike intrusion is considered to be an important cause of formation for the cavi and smaller depressions in Aurorae and Ophir Plana, explaining also melting of ground ice or breaching of cryosphere. Alternatively, the depressions and crater basins may have been filled by regional groundwater table rising during the period(s) when cryosphere was absent or considerably thin. The large quantities of water necessary for explaining the paleohydrological processes in Aurorae and Ophir Plana could have been derived through crustal migration from the crust of higher plains in western Ophir Planum where water existed in confined aquifers or was produced by melting of ground ice due to magmatic heating or climatic shift, or from a paleolake in Candor Chasma further west. 相似文献
27.
VLAD Popa 《Astrophysics and Space Science》2002,282(1):235-244
During the 1999 total solar eclipse we intended to search for photons emitted by a possible radiative decay of the heavier
component of solar neutrinos, using two telescopes: an airborne one, and another at mountain altitude, in Romania(the NOTTE
experiment). The weather conditions did not allow us to perform the measurements. Alternatively, we analyzed a video tape
of the eclipse offered to us by a local television, obtaining some qualitative estimations on the neutrino lifetimes. We present
also a first report on the observations made 21 June 2001, from Zambia.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
28.
P. Negrea A. Popa L. Lupa R. Voda 《International Journal of Environmental Science and Technology》2016,13(8):1873-1882
This article presents the use of ionic liquid in the removal process of thallium ions using solid–liquid extraction by impregnating ionic liquid (1-n-hexyl-3-methylimidazolium chloride) onto an inorganic solid support (Florisil). The influence of impregnation was studied in order to improve the adsorption capacity of the material obtained. Impregnation was realized with the help of a rotavapor. Stirring time and temperature used were varied. Ionic liquid-impregnated materials obtained at different conditions of impregnation were characterized using scanning electron microscopy, energy-dispersive X-ray analysis, and Fourier transform infrared spectroscopy. In order to determine the most efficient adsorbent material, the materials obtained were used in the removal process of thallium ions from aqueous solutions, varying the initial concentration of thallium ions and the stirring time used in the adsorption process. It was observed that for the improving the adsorption capacity of the obtained ionic liquid-impregnated material, it is not necessary to increase the stirring time of the impregnation process but to increase the temperature. The experimental data obtained in the adsorption process were fitted with the Langmuir isotherm. Adsorption of thallium ions onto Florisil impregnated with 1-n-hexyl-3-methylimidazolium chloride ionic liquid corresponds to a pseudo-second-order kinetic model. 相似文献
29.
Alessandro Ellero Leonardo Leoni Michele Marroni Ionel Nicolae Luca Pandolfi Franco Sartori 《Comptes Rendus Geoscience》2002,334(5):347-354
The Fenes Nappe belongs to the stack of tectonic units cropping out in the southern Apuseni Mts (Romania). It is characterised by a structural history consisting of two folding phases that developed during the time spanning from Early Aptian to Late Maastrichtian. The D1 phase produced west-northwest-verging, isoclinal to very tight folds, associated to a slaty cleavage. The main metamorphic imprint of the Fenes Nappe is linked to this deformation phase; illite and chlorite ‘crystallinity’ values indicate metamorphic conditions of the late diagenesis, close to the diagenetic zone/anchizone boundary. The subsequent D2 phase produced north-northwest-verging, parallel folds, not associated with synkinematic recrystallisation. These phases are interpreted as developed during a structural path, which includes burial at a depth of 8–10 km, followed by exhumation at shallower structural levels. To cite this article: A. Ellero et al., C. R. Geoscience 334 (2002) 347–354. 相似文献
30.
Ionel Zlate 《Atmospheric Research》1996,42(1-4)
The rainfall input in hydrological models concerns the mean area precipitation (MAP) values at a certain time resolution, which is required to be higher and higher in the rainfall-runoff modelling, but using space sampled data there is a limited MAP accuracy with respect to the involved time scale. Improved estimates of the rainfall field at small time intervals combine more accurate MAP values performed at a larger scale with the point time variability of data. The usual observation time scale for rain events is 1 h, with acceptable MAP errors, and according to the counting-box method applied in the case of the rainfall contour length there is a scale invariant below such a value.This paper suggests that an improved rainfall input may be obtained by transferring the shape of the hourly rain intensities to each hour in order to generate a finer time distribution of the MAP values, this being accepted if it leads to a better fitting of the simulated and observed hydrographs. This assumption is investigated by numerical experiments with a rainfall-runoff model at different catchment areas. 相似文献