Environmental impacts and simultaneity of positive and negative storm surges on the coast of the Province of Buenos Aires, Argentina     

Jorge L. Pousa  Enrique E. D’Onofrio  Mónica M. E. Fiore  Eduardo E. Kruse 《Environmental Earth Sciences》2013,68(8):2325-2335

The Argentine shore of the Rio de la Plata estuary and its southwards adjacent maritime front are normally affected by extratropical positive and negative storm surges that affect human activities seriously. Positive surges can raise the water level in the estuary by more than 3 m over the predicted tide; thus, flooding the coastal plain where over 13 million people live and causing extensive property damage. Sometimes, there has been loss of life too. Although less populated than the coastal plain, the maritime front has many important tourist resorts and also undergoes severe beach erosion processes and loss of property owing to positive surges. Negative surges are particularly troublesome in the Rio de la Plata because they critically affect navigation safety and drinking water supply by lowering the predicted water level in an amount that sometimes reached more than 4 m. A remarkable point is that the same storm event can simultaneously give rise to a positive surge on the maritime front and a negative one in the Rio de la Plata. The environmental impacts of positive storm surges are strongly aggravated by human intervention. At the same time, sea level rise due to global climatic change has also its influence.  相似文献   

Neural network interpolation of the magnetic field for the LISA Pathfinder Diagnostics Subsystem     

Marc Diaz-Aguilo  Alberto Lobo  Enrique García–Berro 《Experimental Astronomy》2011,30(1):1-21

LISA Pathfinder is a science and technology demonstrator of the European Space Agency within the framework of its LISA mission, which aims to be the first space-borne gravitational wave observatory. The payload of LISA Pathfinder is the so-called LISA Technology Package, which is designed to measure relative accelerations between two test masses in nominal free fall. Its disturbances are monitored and dealt by the diagnostics subsystem. This subsystem consists of several modules, and one of these is the magnetic diagnostics system, which includes a set of four tri-axial fluxgate magnetometers, intended to measure with high precision the magnetic field at the positions of the test masses. However, since the magnetometers are located far from the positions of the test masses, the magnetic field at their positions must be interpolated. It has been recently shown that because there are not enough magnetic channels, classical interpolation methods fail to derive reliable measurements at the positions of the test masses, while neural network interpolation can provide the required measurements at the desired accuracy. In this paper we expand these studies and we assess the reliability and robustness of the neural network interpolation scheme for variations of the locations and possible offsets of the magnetometers, as well as for changes in environmental conditions. We find that neural networks are robust enough to derive accurate measurements of the magnetic field at the positions of the test masses in most circumstances.  相似文献   

Consequences on water retention properties of double-porosity features in a compacted silt   总被引：2，自引：1，他引：1  

Francesca Casini  Jean Vaunat  Enrique Romero  Augusto Desideri 《Acta Geotechnica》2012,7(2):139-150

The paper deals with an experimental investigation aimed at studying microstructural features and their consequences on water retention properties of statically compacted unsaturated silt. The evolution of the microstructure of the aggregate fabric induced by compaction is investigated by studying the pore size distribution changes under different initial conditions (void ratio and water content). The material used is low plasticity silt from Jossigny near Paris, France. A series of mercury intrusion porosimetry tests (MIP) were performed at different void ratios and water contents to provide microstructural information. The arrangement of aggregation/particles and pore network was also investigated with environmental scanning electron microscopy (ESEM). The MIP data were used to determine the water retention curve on drying for the specific pore network configuration induced on compaction. The MIP data were used to formulate and calibrate a multimodal water retention model for a specific pore network configuration, which is obtained by linear superposition of subcurves of a modified van Genuchten type. The study is then complemented with controlled suction oedometer tests on compacted samples to obtain the water retention properties of the material at two different void ratios. Finally, we compare the water retention properties obtained by the simulated progression of the different pore network configurations induced on the hydraulic path with the water retention properties under suction-controlled conditions. Good agreement between the two methods for the drying path is reached.  相似文献   

Mountain glaciation and paleoclimate reconstruction in the Picos de Europa (Iberian Peninsula,SW Europe)     

Enrique Serrano  Juan José González-Trueba  María González-García 《Quaternary Research》2012,78(2):303-314

Geomorphic mapping and stratigraphic analysis of a lake core document the late Quaternary glacial history of the Central and Eastern Massifs of the Picos de Europa, northwestern Spain. The distribution of glacial deposits indicates that at their most advanced positions glaciers occupied 9.1 km², extended as far as 7 km down-valley and had an estimated equilibrium-line altitude (ELA) ranging between 1666 and 1722 m. Radiocarbon dating of sediment deposited in a lake dammed by moraines of this advance show that the maximum glacial extent was prior to 35,280 ± 440 cal yr BP. This advance was followed by two subsequent but less extensive late Pleistocene advances, recorded by multiple moraines flanking both massifs and sedimentary characteristics in the lake deposits. The last recognized glacial episode is the 19th-century maximum extent of small Little Ice Age glaciers in the highest cirques above 2200 m.  相似文献   

Qualitative landslide susceptibility assessment by multicriteria analysis: A case study from San Antonio del Sur, Guantánamo, Cuba   总被引：1，自引：0，他引：1  

Enrique A. Castellanos Abella  Cees J. Van Westen   《Geomorphology》2008,94(3-4):453

Geomorphological information can be combined with decision-support tools to assess landslide hazard and risk. A heuristic model was applied to a rural municipality in eastern Cuba. The study is based on a terrain mapping units (TMU) map, generated at 1:50,000 scale by interpretation of aerial photos, satellite images and field data. Information describing 603 terrain units was collected in a database. Landslide areas were mapped in detail to classify the different failure types and parts. Three major landslide regions are recognized in the study area: coastal hills with rockfalls, shallow debris flows and old rotational rockslides denudational slopes in limestone, with very large deep-seated rockslides related to tectonic activity and the Sierra de Caujerí scarp, with large rockslides. The Caujerí scarp presents the highest hazard, with recent landslides and various signs of active processes. The different landforms and the causative factors for landslides were analyzed and used to develop the heuristic model. The model is based on weights assigned by expert judgment and organized in a number of components such as slope angle, internal relief, slope shape, geological formation, active faults, distance to drainage, distance to springs, geomorphological subunits and existing landslide zones. From these variables a hierarchical heuristic model was applied in which three levels of weights were designed for classes, variables, and criteria. The model combines all weights into a single hazard value for each pixel of the landslide hazard map. The hazard map was then divided by two scales, one with three classes for disaster managers and one with 10 detailed hazard classes for technical staff. The range of weight values and the number of existing landslides is registered for each class. The resulting increasing landslide density with higher hazard classes indicates that the output map is reliable. The landslide hazard map was used in combination with existing information on buildings and infrastructure to prepare a qualitative risk map. The complete lack of historical landslide information and geotechnical data precludes the development of quantitative deterministic or probabilistic models.  相似文献   

Alternative theory for signal contribution sections and depth of investigation characteristics in electrical prospecting          下载免费PDF全文

Enrique Gómez‐Treviño  Carlos Flores 《Geophysical Prospecting》2015,63(3):740-749

We present an alternative to Roy's theorem for direct current regimes with the aim of validating the theoretical basis of signal contribution sections in electrical prospecting. Roy's theorem establishes that the electrical potential at a point can be expressed as an integral over all space of the electric field weighted by the gradient of inverse distance. The integrand is interpreted to represent elementary contributions to the potential that can be analyzed to compare different electrode arrays. Signal contribution sections and depth of investigation characteristics can be beautifully illustrated with important practical applications. However, the electric potential, being the solution of a boundary value problem, cannot be uniquely decomposed into elementary contributions. There is no guarantee for the integrand of a given integral to be meaningful in all situations. In the case of Roy's theorem, the concept has been severely criticized by respected scholars who challenged the scientific legitimacy of his approach. If we are going to keep the concept of elementary contributions alive, we need to go beyond Roy's theorem. In this paper, we develop an alternative theorem and show that it merges with the concept of sensitivity, which is unique and mathematically sound, and is also open to physical validation. This prevents any possible contradictions in the future and, equally important, eliminates the dichotomy between sensitivity and elementary contributions.  相似文献   

On the material dependence of experimental shear fracture orientation     

Enrique Gomez-Rivas  Albert Griera 《中国科学:地球科学(英文版)》2015,58(12):2357-2362

It is not uncommon to observe shear fractures in ductile rocks oriented at more than 45° with respect to the maximum compression direction. Since these orientations cannot be explained with the classic Mohr-Coulumb or Tresca yield criteria, Zheng et al.(Journal of Structural Geology, 35: 1394–1405, 2011) proposed the maximum effective moment(MEM) failure criterion. This rule suggests that shear fractures in ductile rocks form at ?55° with the maximum compression axis and that this orientation is material-independent and, therefore, universal. Zheng et al.(Science China: Earth Sciences, 57(11): 2819–2824, 2014) used data from our own experiments as supporting evidence of their failure criterion. In this contribution we discuss why shear fracture formation in ductile rocks indeed strongly depends on the mechanical properties of the deforming medium, and why experimental data should not be taken to prove the validity of the MEM criterion. The formation mechanisms and orientations of shear fractures in our experiments significantly vary depending on the material strength and degree and type of anisotropy(composite and intrinsic). We therefore demonstrate using experimental data that a universal failure angle in ductile and anisotropic rocks does not apply. Additionally, we highlight some inconsistencies of the MEM criterion.  相似文献   

Precision abundance analysis of bright H ii galaxies     

Guillermo F. Hägele †  Ángeles I. Díaz ‡  Elena Terlevich §  Roberto Terlevich ‡  Enrique Pérez-Montero ¶  Mónica V. Cardaci 《Monthly notices of the Royal Astronomical Society》2008,383(1):209-229

We present high signal-to-noise ratio spectrophotometric observations of seven luminous H  ii galaxies. The observations have been made with the use of a double-arm spectrograph which provides spectra with a wide wavelength coverage, from 3400 to 10 400 Å free of second-order effects, of exactly the same region as that of a given galaxy. These observations are analysed applying a methodology designed to obtain accurate elemental abundances of oxygen, sulphur, nitrogen, neon, argon and iron in the ionized gas. Four electron temperatures and one electron density are derived from the observed forbidden line ratios using the five-level atom approximation. For our best objects, errors of 1 per cent in t _e([O  iii ]), 3 per cent in t _e([O  ii ]) and 5 per cent in t _e([S  iii ]) are achieved with a resulting accuracy of 7 per cent in total oxygen abundances, O/H.
The ionization structure of the nebulae can be mapped by the theoretical oxygen and sulphur ionic ratios, on the one side, and the corresponding observed emission line ratios, on the other – the η and η' plots. The combination of both is shown to provide a means to test photoionization model sequences presently applied to derive elemental abundances in H  ii galaxies.  相似文献   

A new inherent damping model for inelastic time‐history analyses          下载免费PDF全文

J. Enrique Luco  Armando Lanzi 《地震工程与结构动力学》2017,46(12):1919-1939

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Coastal boulder deposit as evidence of an ocean-wide prehistoric tsunami originated on the Atacama Desert coast (northern Chile)     

Manuel Abad  Tatiana Izquierdo  Miguel Cáceres  Enrique Bernárdez  Joaquín Rodriguez-Vidal 《Sedimentology》2020,67(3):1505-1528

A Late Holocene cliff-top deposit of large boulders well above the limits of modern storm waves is described from the southern coast of the Atacama Desert (northern Chile). The largest moved boulder weighs >40 t and field data point to a flood height >18·5 m above high tide level and an inland penetration greater than 284 m from the cliff edge. The minimum flow velocity needed for particle entrainment was estimated as 10·1 ms⁻¹ and the most likely processes of sediment deposition for different boulders were deduced. The boulder distribution, sorting and orientation of imbricated debris, together with the significant wave height of extreme storms reported and the occurrence of interplate earthquakes in the study area indicate that the deposit records a single event, interpreted here as a tsunami wave train rather than exceptional storm waves. The boulder field was dated to between the 13th and the 16th Centuries ce and possibly correlates with the 1420 Oei orphan tsunami, that affected the eastern coast of Japan. A magnitude of 8·8 to 9·4 has been estimated for the earthquake, which may be one of the larger events of a super-cycle of earthquakes in the southern Atacama Desert. These cycle-ending earthquakes involve large rupture areas (lengths in excess of 600 km) and highly destructive ocean-wide tsunamigenic events.  相似文献