Seismic vulnerability of building aggregates through hybrid and indirect assessment techniques     

Rui Maio  Romeu Vicente  Antonio Formisano  Humberto Varum 《Bulletin of Earthquake Engineering》2015,13(10):2995-3014

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Seismic sensitivity analysis of the common structural components of Nepalese Pagoda temples     

Manjip Shakya  Humberto Varum  Romeu Vicente  Aníbal Costa 《Bulletin of Earthquake Engineering》2014,12(4):1679-1703

Nepal is located in a highly active tectonic region of the Himalayan belt, one of the most severe earthquake prone areas of the world. Nepal is lying between the Indian and the Eurasian plate, which are moving continuously, resulting in frequent devastating earthquakes. Moreover, different authors state that the accumulated slip deficit (central seismic gap) is likely to produce large earthquakes in the future. Cultural heritage buildings and monuments are, therefore, at risk, and the eventual cultural loss in the consequence of an earthquake is incalculable. Post-seismic surveys of past earthquakes have shown the potential damage that unreinforced masonry structures, particularly Pagoda temples, may suffer in future earthquakes. Most of the Nepalese Pagoda temples, erected during XIV century, are considered non-engineered constructions that follow very simple rules and construction detailing in respect to seismic resistance requirements and, in some cases, without any concern for seismic action. Presently, conservation and restoration of Nepalese temples is one of the major concerns, since they are considered world heritage with universal value. The present paper is devoted to outline particular building characteristics of the UNESCO classified Nepalese Pagoda temples and the common structural fragilities, which may affect their seismic performance. Moreover, based on a parametric sensitivity analysis, structural weaknesses and fragilities of Pagoda temples were identified associated to the local and traditional construction techniques, detailing and common damages.  相似文献   

Moment and Bayesian wavelet regression from spatially correlated functional data     

R. M. Fernández-Pascual  R. Espejo  M. D. Ruiz-Medina 《Stochastic Environmental Research and Risk Assessment (SERRA)》2016,30(2):523-557

A new wavelet-based estimation methodology, in the context of spatial functional regression, is proposed to discriminate between small-scale and large scale variability of spatially correlated functional data, defined by depth-dependent curves. Specifically, the discrete wavelet transform of the data is computed in space and depth to reduce dimensionality. Moment-based regression estimation is applied for the approximation of the scaling coefficients of the functional response. While its wavelet coefficients are estimated in a Bayesian regression framework. Both regression approaches are implemented from the empirical versions of the scaling and wavelet auto-covariance and cross-covariance operators, characterizing the correlation structure of the spatial functional response. Weather stations in ocean islands display high spatial concentration. The proposed estimation methodology overcomes the difficulties arising in the estimation of ocean temperature field at different depths, from long records of ocean temperature measurements in these stations. Data are collected from The World-Wide Ocean Optics Database. The performance of the presented approach is tested in terms of 10-fold cross-validation, and residual spatial and depth correlation analysis. Additionally, an application to soil sciences, for prediction of electrical conductivity profiles is also considered to compare this approach with previous related ones, in the statistical analysis of spatially correlated curves in depth.  相似文献   

Nutrient dynamics in water and sediment of Mediterranean ponds across a wide hydroperiod gradient     

María Sahuquillo  Maria Rosa Miracle  Sara María Morata  Eduardo Vicente 《Limnologica》2012,42(4):282-290

In Mediterranean ponds, summer drought enhances seasonality whose intensity varies along topographic and climatic gradients. The alternation of wet and dry periods in rain dependent ponds affects their biogeochemistry and differentiates them from ponds fed by more stable water sources, such as groundwater springs. Superimposed onto this, land use is also a very strong factor of variability. In this study we compared nutrients and organic matter concentrations, in water and in sediment, among different types of Mediterranean ponds based on the source of water, hydroperiod and land use. Forty-three ponds were sampled in Eastern Spain corresponding to five pond types: (1) permanent spring ponds in lowlands, (2) permanent spring ponds in mountains, (3) semi-permanent rain ponds, (4) temporary rain ponds with long hydroperiod and (5) temporary rain ponds with short hydroperiod.The results of this study indicate relevant differences among these pond types. The temporary rain ponds with short hydroperiod are characterized by high turbidity due to suspension of sediment particles rich in phosphorous adsorbed onto them (argillotrophic aquatic systems). They are used for watering domestic sheep that enhance sediment suspension by trampling. Total phosphorous (TP) concentrations in the water are high (like those of hypertrophic lakes), but planktonic chlorophyll a is very low and not correlated with TP, because of the low P-bioavailavility in the water. At the other extreme, we have permanent ponds in lowlands fed by groundwater springs. They are heavily loaded with nitrates due to the surrounding intensive agriculture. In these and other permanent/semipermanent ponds chlorophyll is highly correlated with TP. Sediment characteristics provide a good indication of the hydroperiod, since desiccation has important effects on biogeochemical transformations. A threshold of 5% organic matter (OM) in the sediment separates temporary ponds with a short hydroperiod from those with a long hydroperiod, and a threshold of 8% separates the later from the semi-permanent and permanent ponds. Besides OM reduction, important loss of N occurs during desiccation through mineralization, ammonia volatization and the sequential nitrification/denitrification pathway. On the other hand, the increase of organic P mineralization in dry sediments does not represent a loss of P from the system, since o-P remains adsorbed or bound onto the soil. This leads to a low TN/TP ratio in sediments in temporary ponds with short hydroperiod. These characteristics have to be taken into account when establishing pond typologies and ecological thresholds to assess water quality in these unique aquatic habitats.  相似文献   

The Ebro River in the 20th century or the ecomorphological transformation of a large and dynamic Mediterranean channel     

Fernando Magdaleno  J. Anastasio Fernández  Silvia Merino 《地球表面变化过程与地形》2012,37(5):486-498

In the first decades of the 20th century, the Ebro River was the Iberian channel with the most active fluvial dynamics and the most remarkable spatial‐temporal evolution. Its meandering typology, the dimensions of its floodplain, and the singularities of its flow regime produced an especially interesting set of river functions. The largest dynamics of the Ebro River are concentrated along the meandering profile of the central sector. During the 20th century, this sector experienced a large alteration of its geomorphological structure. We present here an analysis of this evolution through the cartographic study of a long segment of the river (~250 km) in 1927, 1956 and 2003. The results show a large reduction in bank sinuosity, a progressive loss of fluvial territory, and a large decrease in channel width. These changes are especially clear in the areas previously most ecologically connected with the active channel. The fluvial territory of the river in 2003 was approximately half that found during the first decades of the 20th century. Forest plantations, which were non‐existent in 1927, occupied more than 1500 ha of the study area in the last decade. This intense geomorphological transformation becomes ecologically visible in (i) a 35% reduction of the area occupied by riparian vegetation; (ii) a loss of the heterogeneity of riparian forest spots, which were formerly structured in an irregular mosaic far from the river thalweg; and (iii) a modification of the riparian forest structure, which is currently linear, uniform, thin and very close to the river axis. The ecomorphological alteration was intensified by the remarkable reduction in bank length (13%) and the reduced dynamism of the present river system, indicated by an increase in the percentage of fluvial territory occupied by riparian forests and a reduction in the area occupied by the active channel. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Seismic vulnerability assessment and characterisation of the buildings on Faial Island, Azores     

Filipe Neves  Aníbal Costa  Romeu Vicente  C. Sousa Oliveira  Humberto Varum 《Bulletin of Earthquake Engineering》2012,10(1):27-44

The earthquake of the 9th of July 1998 that hit in the central group of the Azores archipelago greatly affected the islands of Faial, Pico and S?o Jorge, reaching a magnitude of Mw 6.2 with the epicentre located about 15km northeast of the Faial Island. This earthquake allowed the collection of an unprecedented quantity of data concerning the characterisation of the building stock and the damage suffered by construction. This is the main purpose of this research, consisting essentially of three main aspects: (i) A detailed characterisation of the building stock, assigning a five category classification, from old traditional rubble stone masonry to reinforced concrete moment framed buildings; (ii) A detailed damage grade classification based on the different damage mechanisms observed; and, (iii) A seismic vulnerability assessment of the building stock. The results of the vulnerability assessment together with the building stock database and damage classification were integrated into a GIS tool, allowing the spatial visualation of damage scenarios, which is potentially useful for the planning of emergency response strategies and retrofitting priorities to mitigate and manage seismic risk.  相似文献   

Introduction to Earth Sciences and Mathematics, Volume II     

A. G. Camacho  J. I. Díaz  J. Fernández 《Pure and Applied Geophysics》2008,165(8):1459-1463

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Quaternary landscape evolution and erosion rates for an intramontane Neogene basin (Guadix–Baza basin, SE Spain)     

Jos Vicente Prez-Pea  Jos Miguel Azan  Antonio Azor  Paola Tuccimei  Marta Della Seta  Michele Soligo 《Geomorphology》2009,106(3-4):206-218

The landscape evolution in Neogene intramontane basins is a result of the interaction of climatic, lithologic, and tectonic factors. When sedimentation ceases and a basin enters an erosional stage, estimating erosion rates across the entire basin can offer a good view of landscape evolution. In this work, the erosion rates in the Guadix–Baza basin have been calculated based on a volumetric estimate of sediment loss by river erosion since the Late Pleistocene. To do so, the distribution of a glacis surface at ca. 43 kyr, characterised by a calcrete layer that caps the basin infilling, has been reconstructed. To support this age, new radiometric data of the glacis are presented. The volume of sediment loss by water erosion has been calculated for the entire basin by comparing the reconstructed geomorphic surface and the present-day topography. The resulting erosion rates vary between 4.28 and 6.57 m³ ha^− 1 yr^− 1, and are the consequence of the interaction of climatic, lithologic, topographic, and tectonic factors. Individual erosion rates for the Guadix and Baza sub-basins (11.80 m³ ha^− 1 yr^− 1 and 1.77 m³ ha^− 1 yr^− 1 respectively) suggest different stages of drainage pattern evolution in the two sub-basins. We attribute the lower values obtained in the Baza sub-basin to the down-throw of this sub-basin caused by very recent activity along the Baza fault.  相似文献   

Comparison of marine and river water humic substances in a Patagonian environment (Argentina)     

María del Carmen Scapini  Víctor Hugo Conzonno  Vilma Teresa Balzaretti  Alicia Fernández Cirelli 《Aquatic Sciences - Research Across Boundaries》2010,72(1):1-12

Structural aspects of humic substances (HSs) in marine waters of Engaño Bay (Atlantic Ocean) and water from the Chubut River (Patagonia, Argentina) were compared. The HSs were isolated, purified, and analyzed using a multiple-method approach for structural characterization: elemental analysis, nuclear magnetic resonance (¹³C and ¹H NMR), infrared spectroscopy (FTIR), UV-visible absorption and fluorescence. Similarities between the marine and freshwater components were evaluated on the basis of N and O contents, H/C and C/N atomic ratios, infrared bands from nitrogen-containing and carboxylic groups, percentage of functional groups obtained from NMR spectra, spectral slope coefficient of absorption spectra, absorbance ratios at 250 and 365 nm (E ₂/E ₃), aromaticity, excitation–emission matrices and fluorescence quantum yield. Both the Engaño Bay and Chubut River waters have HSs that are mainly composed of fulvic acids (FAs); although they are very similar, they may be distinguished from one another. Similarities include the predominance of aliphatic carbon content (low aromatic content); however, the water bodies differed in their content of proteins and carboxylic acids. The Engaño Bay FAs have mainly an aquatic origin; although the Chubut River FAs suggest a similar aquagenic origin, there is also evidence of contributions from pedogenic FAs.  相似文献   

Goodness-of-fit tests for the spatial spectral density   总被引：1，自引：1，他引：0  

Rosa M. Crujeiras  Rubén Fernández-Casal  Wenceslao González-Manteiga 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(1):67-79

Detection and modeling the spatial correlation is an important issue in spatial data analysis. We extend in this work two different goodness-of-fit testing techniques for the spatial spectral density. The first approach is based on a smoothed version of the ratio between the periodogram and a parametric estimator of the spectral density. The second one is a generalized likelihood ratio test statistic, based on the log-periodogram representation as the response variable in a regression model. As a particular case, we provide tests for independence. Asymptotic normal distribution of both statistics is obtained, under the null hypothesis. For the application in practice, a resampling procedure for calibrating these tests is also given. The performance of the method is checked by a simulation study. Application to real data is also provided.  相似文献