Extensional salt tectonics in the partially inverted Cotiella post-rift basin (south-central Pyrenees): structure and evolution   总被引：1，自引：0，他引：1  

Berta López-Mir  Josep Anton Muñoz  Jesús García-Senz 《International Journal of Earth Sciences》2015,104(2):419-434

  相似文献   

Effects of UV radiation on the RNA/DNA ratio of Copepods from Antarctica and Chile     

Paulo F. Lagos  M. Jesús Valdés  Karen Manríquez 《极地研究(英文版)》2015,(2)

The effect of ultraviolet (UV) radiation on marine organisms has been an important focus of recent research, with depletion of the ozone layer resulting in increased UV radiation at high latitudes. Sev...  相似文献   

Linking earthquake-triggered paleolandslides to their seismic source and to the possible seismic event that originated them in a portion of the Argentine Precordillera (31°–33°S)     

Junquera-Torrado  Sebastián  Moreiras  Stella M.  Rodríguez-Peces  Martín Jesús  Sepúlveda  Sergio A. 《Natural Hazards》2021,106(1):43-78

Natural Hazards - A total of 36 rock slides were selected for analysing a probable seismic source in the active Andean Precordillera (31°–33°S), the most seismic region of...  相似文献   

Tectonic indentation in the central Alboran Sea (westernmost Mediterranean)          下载免费PDF全文

Ferran Estrada  Jesús Galindo‐Zaldívar  Juan Tomás Vázquez  Gemma Ercilla  Elia D'Acremont  Belén Alonso  Christian Gorini 《地学学报》2018,30(1):24-33

The Alboran Sea constitutes a Neogene–Quaternary basin of the Betic–Rif Cordillera, which has been deformed since the Late Miocene during the collision between the Eurasian and African plates in the westernmost Mediterranean. NNE–SSW sinistral and WNW–ESE dextral conjugate fault sets forming a 75° angle surround a rigid basement spur of the African plate, and are the origin of most of the shallow seismicity of the central Alboran Sea. Northward, the faults decrease their transcurrent slip, becoming normal close to the tip point, while NNW–SSE normal and sparse ENE–WSW reverse to transcurrent faults are developed. The uplifting of the Alboran Ridge ENE–WSW antiform above a detachment level was favoured by the crustal layering. Despite the recent anticlockwise rotation of the Eurasian–African convergence trend in the westernmost Mediterranean, these recent deformations—consistent with indenter tectonics characterised by a N164°E trend of maximum compression—entail the highest seismic hazard of the Alboran Sea.  相似文献   

Global optimization of the Gauss conformal mappings of an ellipsoid to a sphere     

Mercedes Bermejo-Solera  Jesús Otero 《Journal of Geodesy》2010,84(8):481-489

The Gauss conformal mappings (GCMs) of an oblate ellipsoid of revolution to a sphere are those that transform the meridians into meridians, and the parallels into parallels of the sphere. The infinitesimal-scale function associated with these mappings depends on the geodetic latitude and contains three parameters, including the radius of the sphere. Gauss derived these constants by imposing local optimum conditions on certain parallel. We deal with the problem of finding the constants to minimize the Chebyshev or maximum norm of the logarithm of the infinitesimal-scale function on a given ellipsoidal segment (the region contained between two parallels). We show how to solve this minimax problem using the intrinsic function fminsearch of Matlab. For a particular ellipsoidal segment, we get the solution and show the alternation property characteristic of best Chebyshev approximations. For a pair of points relatively close in the ellipsoid at different latitudes, the best minimax GCM on the segment defined by these points is used to approximate the geodesic distance between them by the spherical distance between their projections on the corresponding sphere. This approach, combined with the best locally GCM if the points are on the same parallel, is illustrated by applying it to some case studies but specially to a 10° × 10° region contained between portions of two parallels and two meridians. In this case, the maximum absolute error of this spherical approximation is equal to 2.9 mm occurring at a distance about 1,360 km. This error decreases up to 0.94 mm on an 8° × 8° region of this type. So, the spherical approximation to the solution of the inverse geodesic problem by best GCM can be acceptable in many practical geodetic activities.  相似文献   

Factors determining subsidence in urbanized floodplains: evidence from MT‐InSAR in Seville (southern Spain)          下载免费PDF全文

Ana Ruiz‐Constán  Antonio M. Ruiz‐Armenteros  Jesús Galindo‐Zaldívar  Francisco Lamas‐Fernández  Joaquim João Sousa  Carlos Sanz de Galdeano  Antonio Pedrera  Sergio Martos‐Rosillo  Miguel Caro Cuenca  J. Manuel Delgado  Ramon F. Hanssen  Antonio J. Gil 《地球表面变化过程与地形》2017,42(14):2484-2497

Major rivers have traditionally been linked with important human settlements throughout history. The growth of cities over recent river deposits makes necessary the use of multidisciplinary approaches to characterize the evolution of drainage networks in urbanized areas. Since under‐consolidated fluvial sediments are especially sensitive to compaction, their spatial distribution, thickness, and mechanical behavior must be studied. Here, we report on subsidence in the city of Seville (Southern Spain) between 2003 and 2010, through the analysis of the results obtained with the Multi‐Temporal InSAR (MT‐InSAR) technique. In addition, the temporal evolution of the subsidence is correlated with the rainfall, the river water column and the piezometric level. Finally, we characterize the geotechnical parameters of the fluvial sediments and calculate the theoretical settlement in the most representative sectors. Deformation maps clearly indicate that the spatial extent of subsidence is controlled by the distribution of under‐consolidated fine‐grained fluvial sediments at heights comprised in the range of river level variation. This is clearly evident at the western margin of the river and the surroundings of its tributaries, and differs from rainfall results as consequence of the anthropic regulation of the river. On the other hand, this influence is not detected at the eastern margin due to the shallow presence of coarse‐grain consolidated sediments of different terrace levels. The derived results prove valuable for implementing urban planning strategies, and the InSAR technique can therefore be considered as a complementary tool to help unravel the subsidence tendency of cities located over under‐consolidated fluvial deposits. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Energy capacity and seismic performance of RC waffle-flat plate structures under two components of far-field ground motions: Shake table tests     

Amadeo Benavent-Climent  David Galé-Lamuela  Jesús Donaire-Avila 《地震工程与结构动力学》2019,48(8):949-969

The bidirectional response of a portion of a reinforced concrete (RC) waffle-flat plate (WFP) structure subjected to far-field ground motions is studied through shake table tests. The test specimen is a scaled portion of a prototype structure designed under current building codes and located in a region of moderate seismicity of the Mediterranean area. The specimen was subjected to a sequence of tests of increasing acceleration amplitude that respectively represented very frequent, frequent, design, and very rare earthquakes at the site. The test structure performed well (basically in the elastic domain) under very frequent and frequent earthquakes, approached the boundary between the performance levels of life safety and near collapse under the design earthquake, and collapsed under the very rare earthquake. Damage concentrated at column bases and at the transverse beams of the exterior plate-to-column connection. Columns dissipated about 10% of the total energy that contributes to damage, and the rest was dissipated by the exterior plate-column connection. The total energy input on the structure until collapse under the bidirectional seismic action was very close to the value obtained in previous studies on a similar specimen tested under unidirectional ground motions. The capacity curve estimated from the experimental base shear vs top displacement relationship suggests it is best to use a behavior factor of at most q = 2 when designing WFP structures with the reduced-spectrum force-based approach.  相似文献   

Spatial distribution of morphometric parameters of glacial cirques in the Central Pyrenees(Aran and Boí valleys)     

Luis LOPES  Marc OLIVA  Marcelo FERNANDES  Paulo PEREIRA  Pedro PALMA  Jesús RUIZ-FERNáNDEZ 《山地科学学报》2018,15(10):2103-2119

Glacial cirques are typical landscape features of mid-latitude mountain environments like the Central Pyrenees. Their morphology as well as their spatial distribution provides insights about past glaciers and climates. In this study, we examine the distribution, morphometrical and topographical characteristics of glacial cirques in two U-shaped glacial valleys located in the Central Pyrenees – the Aran and the Boí valleys. They are located in different aspects of this mountain range(north vs south) under different climatic influences that promoted distinct glaciation patterns during the late Pleistocene. The spatial mapping of these landforms was carried out using high-resolution imagery and field observations. We analysed the data of the morphometrical and topographical variables of the glacial cirques by using different statistical and geospatial methods in order tounveil the factors controlling their formation and development. A total of 186 glacial cirques were mapped in the study area, including 119 in the Aran and 67 in the Boí valleys. The local topography and microclimate conditions lead to substantial differences in both areas in terms of the morphology and dimensions of the cirques. Glacial cirques in Boí are distributed at slightly higher elevations than in Aran and they are also larger, though their dimensions decrease with elevation in both valleys. Aran cirques are mostly oriented NE, while Boí landforms do not show any prevailing aspect. Even though lithology does not control the distribution of the glacial cirques, some specific lithological settings may favour the development of larger cirques. In general, glacial cirques in the Aran and the Boí valleys show morphometrical properties similar to those reported in other mid-latitude mountain ranges.  相似文献   

Benchmarking of two three-dimensional numerical models in time/space domain to predict railway-induced ground vibrations     

Jesus Fernandez-Ruiz  Luis E.Medina Rodriguez  Pedro Alves Costa  Margarita Martinez-Diaz 《地震工程与工程振动(英文版)》2021,20(1):245-256

In the last 30 years,the scientific community has developed and proposed different models and numerical approaches for the study of vibrations induced by railway traffic.Most of them are formulated in the frequency/wave number domain and with a 2.5D approach.Three-dimensional numerical models formulated in the time/space domain are less frequently used,mainly due to their high computational cost.Notwithstanding,these models present very attractive characteristics,such as the possibility of considering nonlinear behaviors or the modelling of excess pore pressure and non-homogeneous and non-periodic geometries in the longitudinal direction of the track.In this study,two 3D numerical approaches formulated in the time/space domain are compared and experimentally validated.The first one consists of a finite element approach and the second one of a finite difference approach.The experimental validation in an actual case situated in Carregado(Portugal)shows an acceptable fitting between the numerical results and the actual measurements for both models.However,there are some differences among them.This study therefore includes some recommendations for their use in practical soil dynamics and geotechnical engineering.  相似文献   

Digital Image Processing of Schmidt Objective Prism Spectra     

Ignacio Ferrin  Francisco Fuenmayor  Jesús Hernández 《Experimental Astronomy》1999,9(4):205-211

The analysis of stellar spectra taken with the 4 degree prism attached to the 1 m Schmidt telescope of the National Observatory of Venezuela, requires special techniques to reduce the noise in the very small image (5 × 80 pixels), and to enhance the faint absorption lines. In this work we describe the processing techniques that we have used to insure that the information contained is not lost in the noise. Our protocol has achieved a reduction of the noise to 7% of its original value using these special techniques, the last of which is Fourier Analysis.  相似文献