Unusual Carbonatite Lavas from Active Volcano, Oldoinyo Lengai

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Unusual Carbonatite Lavas from Active Volcano, Oldoinyo Lengai     

Tangled up in folds: tectonic significance of superimposed folding at the core of the Central Iberian curve (West Iberia)

The amalgamation of Pangea during the Carboniferous produced a winding mountain belt: the Variscan orogen of West Europe. In the Iberian Peninsula, this tortuous geometry is dominated by two major structures: the Cantabrian Orocline, to the north, and the Central Iberian curve (CIC) to the south. Here, we perform a detailed structural analysis of an area within the core of the CIC. This core was intensively deformed resulting in a corrugated superimposed folding pattern. We have identified three different phases of deformation that can be linked to regional Variscan deformation phases. The main collisional event produced upright to moderately inclined cylindrical folds with an associated axial planar cleavage. These folds were subsequently folded during extensional collapse, in which a second fold system with subhorizontal axes and an intense subhorizontal cleavage formed. Finally, during the formation of the Cantabrian Orocline, a third folding event refolded the two previous fold systems. This later phase formed upright open folds with fold axis trending 100° to 130°, a crenulation cleavage and brittle–ductile transcurrent conjugated shearing. Our results show that the first and last deformation phases are close to coaxial, which does not allow the CIC to be formed as a product of vertical axis rotations, i.e. an orocline. The origin of the curvature in Central Iberia, if a single process, had to be coeval or previous to the first deformation phase.     

Groundwater overexploitation and soil subsidence monitoring on Recife plain (Brazil)

Facing natural disasters is a priority challenge for cities, exacerbated by increases in urban population and climate change. Improving the resilience of cities is a critical need for the international community and especially for territories exposed to multiple risks, such as Chile. Although disasters are always tragic, the recovery and reconstruction post-disaster may provide a unique opportunity to prevent future suffering, enhancing the resilience of local communities. This paper presents the analysis of two Chilean reconstruction programmes applied in Mehuin and Dichato, after the earthquake and tsunami of 22 May 1960 and 27 February 2010, respectively. In both cases, reconstruction programmes were supported by the Chilean Government, but using different approaches: one focused on providing housing for people injured in the earthquake, while the other also included urban amenities and services. This article proposes an urban morphology analysis framework; in addition, it presents the assessment of the two case studies before and after a disaster, thus evaluating their resilience. By comparing urban morphology resilience pre- and post-disaster, a discussion about the effectiveness of two reconstruction approaches is presented. Finally, conclusions and recommendations to better integrate resilience into urban planning are proposed, with the aim of opening the discussion about how to make cities more resilient to natural disasters.     

Influence of soil non-linearity on the dynamic response of high-speed railway tracks

The main objectives of this paper are the evaluation of the relevance of the non-linear behaviour of the soil on the track response and the validation of a methodology, which includes these effects through an equivalent linear analysis. The proposed numerical model is based on 2.5D finite/infinite elements method, coupled with an iterative procedure in order to obtain an agreement between the strain levels and the dynamic properties of the materials. In order to validate the model, the case study of Ledsgard was simulated, and the experimental and numerical results of displacements of the track were compared, considering several circulation speeds for the X2000 train. From the results, it is possible to recognize that the stiffness degradation, function of the strain level, plays a relevant role for the case of high-speed railway lines on soft ground. Moreover, the simulations developed with the proposed methodology provided similar results to those observed, independently of the train speed, contrary to what was obtained when the elastic linear model was used.     

Modal response analysis of multi‐support structures using a random vibration approach

A formulation is developed for modal response analysis of multi‐support structures using a random vibration approach. The spectral moments of the structural response are rigorously decomposed into contributions from spectral moments of uncoupled modal responses. An advantage of the proposed formulation is that the total dynamic response can be obtained on the basis of mode by mode uncoupled analyses. The contributions to the total response from modal responses under individual support ground motions and under cross‐correlated pairs of support ground motions can be recognized explicitly. The application and performance of the formulation is illustrated by means of an example using a well‐established coherency spectrum model and widely known power spectra models, such as white noise and Kanai–Tajimi. The first three spectral moments of displacement, shear, and bending moment responses are computed, showing that the formulation produces the same results as the exact solution. Copyright © 2015 John Wiley & Sons, Ltd.     

Particulate matter geochemistry of a highly industrialized region in the Caribbean:Basis for future toxicological studies

Air pollution has become an important issue,especially in Caribbean urban areas,and,particulate matter(PM)emitted by different natural and anthropogenic sources causes environmental and health issues.In this work,we studied the concentrations of PM₁₀ and PM_2.5 sources in an industrial and port urban area in the Caribbean region of Colombia.PM samples were collected within 48-h periods between April and October 2018 by using a Partisol 2000 i-D sampler.Elemental geochemical characterization was performed by X-ray fluorescence(XRF)analysis.Further,ionic species and black carbon(BC)were quantified by ion chromatography and reflectance spectroscopy,respectively.Using the Positive Matrix Factorization(PMF)receptor model,the contributions of PM sources were quantified.The average concentration of PM₁₀ was 46.6±16.2μg/m³,with high concentrations of Cl and Ca.For PM_2.5,the average concentration was 12.0±3.2μg/m³,and the most abundant components were BC,S,and Cl.The receptor model identified five sources for PM₁₀ and PM_2.5.For both fractions,the contributions of marine sea spray,re-suspended soil,and vehicular traffic were observed.In addition,PM_2.5 included two mixed sources were found to be fuel oil combustion with fertilizer industry emissions,and secondary aerosol sources with building construction emissions.Further,PM₁₀ was found to also include building construction emissions with re-suspended soil,and metallurgical industry emissions.These obtained geochemical atmospheric results are important for the implementation of strategies for the continuous improvement of the air quality of the Caribbean region.     

港口集装箱物流的流体力学模拟研究初探

港口集装箱物流在国民经济发展中的作用日苴凸显,许多国家对此进行了深入研究,但多未涉及到物流过程的自然规律。受到近年来应用广泛的遗传算法、神经网络和水电比拟等方法的启示,注意到港口集装箱物流与自然界的流体运动具有相似性,故可采用流体力学方法来模拟港口集装箱物流的运动过程,以揭示港口集装箱物流的内在运动规律,找到物流过程中的敏感环节,最终达到优化物流过程的目的。对利用流体力学对港口集装箱物流进行模拟的研究方法进行了初步探讨。     

Controlling factors and environmental implications of mercury contamination in urban and agricultural soils under a long-term influence of a chlor-alkali plant in the North–West Portugal

This study aims at assessing the extent of total mercury (Hg) contamination in urban and agricultural soils under long-term influence of a chlor-alkali plant, located at about 1 km away from a town centre. Moreover, it aims at identifying the main factors controlling Hg contents’ distribution and associated potential hazards to environment and human health. The median value of total Hg for soil surface layer (0–10 cm) was 0.20 mg/kg (data ranging from 0.050 to 4.5 mg/kg) and for subsurface layer (10–20 cm) 0.18 mg/kg (data ranging from 0.046 to 3.0 mg/kg). The agricultural area showed higher Hg concentrations (ranging from 0.86 to 4.5 mg/kg) than urban area (ranging from 0.05 to 0.61 mg/kg), with some results exceeding target values set by the Dutch guidelines. Mercury concentrations observed in the studied area are more likely to be associated with the influence of the chlor-alkali plant and with the use of historically contaminated sludges and water from a nearby lagoon in agriculture, than to the impacts of urban development. The statistical correlations between Hg concentrations and soil properties suggest that anthropogenic metal sources should influence the spatial distribution more than the geological properties. Although the Hg emissions were drastically reduced 10 years ago, the area under influence of the chlor-alkali plant is still facing potential health and environmental threats arising from soil contamination.     

Gravity data as a tool for landfill study

This paper shows the potential of gravity data to map a buried landfill bottom topography. To this end, a gravity inversion method is presented for estimating the landfill’s bottom depths at discrete points assuming a decrease of the density contrast with depth according to a hyperbolic law. The method’s efficiency was tested using synthetic data from simulated waste landfills, producing estimated bottom topographies very close to the true ones. The method’s potentiality has been further evaluated in applying it to the gravity data from the abandoned Thomas Farm Landfill site, Indiana, USA, whose bottom topography is known. The estimated topography showed close agreement with the known Thomas Farm Landfill’s bottom topography.