Potential Use of Remote Sensing Techniques for Exploration of Iron Deposits in Western Sahara and Southwest of Algeria     

Andrea Ciampalini  Francesca Garfagnoli  Chiara Del Ventisette  Sandro Moretti 《Natural Resources Research》2013,22(3):179-190

At present, Western Sahara is politically one of the most sensitive areas of the World. Its economic development could be achieved through the exploitation of mineral resources that can be found in the almost unexplored area administrated by the Saharawi Arab Democratic Republic. In this paper, we describe applications of known and cost-effective remote sensing techniques to detect and map areas containing mineral deposits, through the enhancement of Landsat ETM+ imageries. Several image processing techniques (false color composite, band ratioing, and principal component analysis) were used to highlight the presence of iron deposits. Two test areas were selected, one in Western Sahara and another one in Algeria. The occurrence of iron deposits in these test areas was assured using literature data for the Algerian test site and through a field campaign for the Western Sahara. There is good agreement between the ground truth data and the results obtained by the enhancements of the satellite images. Landsat images can be downloaded free of charge and their enhancements does not need expensive hardware or software tools. Therefore this technology could be transferred to the Saharawi technicians, enabling them to explore and manage the mineral resources of their own country independently.  相似文献   

Slope instability induced by volcano-tectonics as an additional source of hazard in active volcanic areas: the case of Ischia island (Italy)   总被引：1，自引：0，他引：1  

Marta Della Seta  Enrica Marotta  Giovanni Orsi  Sandro de Vita  Fabio Sansivero  Paola Fredi 《Bulletin of Volcanology》2012,74(1):79-106

Ischia is an active volcanic island in the Gulf of Naples whose history has been dominated by a caldera-forming eruption (ca. 55 ka) and resurgence phenomena that have affected the caldera floor and generated a net uplift of about 900 m since 33 ka. The results of new geomorphological, stratigraphical and textural investigations of the products of gravitational movements triggered by volcano-tectonic events have been combined with the information arising from a reinterpretation of historical chronicles on natural phenomena such as earthquakes, ground deformation, gravitational movements and volcanic eruptions. The combined interpretation of all these data shows that gravitational movements, coeval to volcanic activity and uplift events related to the long-lasting resurgence, have affected the highly fractured marginal portions of the most uplifted Mt. Epomeo blocks. Such movements, mostly occurring since 3 ka, include debris avalanches; large debris flows (lahars); smaller mass movements (rock falls, slumps, debris and rock slides, and small debris flows); and deep-seated gravitational slope deformation. The occurrence of submarine deposits linked with subaerial deposits of the most voluminous mass movements clearly shows that the debris avalanches impacted on the sea. The obtained results corroborate the hypothesis that the behaviour of the Ischia volcano is based on an intimate interplay among magmatism, resurgence dynamics, fault generation, seismicity, slope oversteepening and instability, and eruptions. They also highlight that volcano-tectonically triggered mass movements are a potentially hazardous phenomena that have to be taken into account in any attempt to assess volcanic and related hazards at Ischia. Furthermore, the largest mass movements could also flow into the sea, generating tsunami waves that could impact on the island’s coast as well as on the neighbouring and densely inhabited coast of the Neapolitan area.  相似文献   

Hydromorphological frameworks: emerging trajectories     

A. M. Gurnell  M. Rinaldi  A. D. Buijse  G. Brierley  H. Piégay 《Aquatic Sciences - Research Across Boundaries》2016,78(1):135-138

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Impacts of land use on the hydrological response of tropical Andean catchments          下载免费PDF全文

Boris F. Ochoa‐Tocachi  Wouter Buytaert  Bert De Bièvre  Rolando Célleri  Patricio Crespo  Marcos Villacís  Carlos A. Llerena  Luis Acosta  Mauricio Villazón  Mario Guallpa  Junior Gil‐Ríos  Paola Fuentes  Dimas Olaya  Paúl Viñas  Gerver Rojas  Sandro Arias 《水文研究》2016,30(22):4074-4089

Changes in land use and land cover are major drivers of hydrological alteration in the tropical Andes. However, quantifying their impacts is fraught with difficulties because of the extreme diversity in meteorological boundary conditions, which contrasts strongly with the lack of knowledge about local hydrological processes. Although local studies have reduced data scarcity in certain regions, the complexity of the tropical Andes poses a big challenge to regional hydrological prediction. This study analyses data generated from a participatory monitoring network of 25 headwater catchments covering three of the major Andean biomes (páramo, jalca and puna) and links their hydrological responses to main types of human interventions (cultivation, afforestation and grazing). A paired catchment setup was implemented to evaluate the impacts of change using a ‘trading space‐for‐time’ approach. Catchments were selected based on regional representativeness and contrasting land use types. Precipitation and discharge have been monitored and analysed at high temporal resolution for a time period between 1 and 5 years. The observed catchment responses clearly reflect the extraordinarily wide spectrum of hydrological processes of the tropical Andes. They range from perennially humid páramos in Ecuador and northern Peru with extremely large specific discharge and baseflows, to highly seasonal, flashy catchments in the drier punas of southern Peru and Bolivia. The impacts of land use are similarly diverse and their magnitudes are a function of catchment properties, original and replacement vegetation and management type. Cultivation and afforestation consistently affect the entire range of discharges, particularly low flows. The impacts of grazing are more variable but have the largest effect on the catchment hydrological regulation. Overall, anthropogenic interventions result in increased streamflow variability and significant reductions in catchment regulation capacity and water yield, irrespective of the hydrological properties of the original biome. Copyright © 2016 The Authors. Hydrological Processes. Published by John Wiley & Sons Ltd.  相似文献   

Spatio‐temporal patterns of channel changes in response to a major flood event: the case of the Magra River (central–northern Italy)          下载免费PDF全文

Laura Nardi  Massimo Rinaldi 《地球表面变化过程与地形》2015,40(3):326-339

On October 25^th 2011, the Magra River (central–northern Italy) was affected by a significant flood event with an estimated return interval ranging from 30 to 200 years. This study investigates the morphological responses of the Magra River to this major flood event with the aims of (i) documenting the channel changes which occurred in response to the flood; (ii) analysing this response within the context of the historical trend of width changes; (iii) investigating the possible factors controlling the spatial pattern and the intensity of the observed changes. Significant channel widening was documented along the entire length studied (about 34 km), ranging from 3% to 90% of the pre‐flood channel width. Braided reaches were characterized by the most severe planimetric changes. Although characterized by high rates of change, these variations are, however, amply included in the historical range of channel width variability over approximately the last 150 years (from 1877 to present day), and are comparable with ( though generally lower than) the channel width of the 1950s. Statistical analyses (simple and multiple regressions) between the observed changes in channel width and a series of selected morphological and hydraulic controlling factors showed no robust correlations to explain the spatial pattern and the variability of channel adjustments. Instead, major adjustments occurred along reaches characterized by the confluence of those streams draining the sub‐catchments where the storm was concentrated. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

The ITalian ACcelerometric Archive (ITACA): processing of strong-motion data   总被引：1，自引：1，他引：0  

Marco Massa  Francesca Pacor  Lucia Luzi  Dino Bindi  Giuliano Milana  Fabio Sabetta  Antonella Gorini  Sandro Marcucci 《Bulletin of Earthquake Engineering》2010,8(5):1175-1187

The Italian strong-motion database was created during a joint project between Istituto Nazionale di Geofisica e Vulcanologia (INGV, Italian Institute for Geophysics and Vulcanology) and Dipartimento della Protezione Civile (DPC, Italian Civil Protection). The aim of the project was the collection, homogenization and distribution of strong motion data acquired in Italy in the period 1972–2004 by different institutions, namely Ente Nazionale per l’Energia Elettrica (ENEL, Italian electricity company), Ente per le Nuove tecnologie, l’Energia e l’Ambiente (ENEA, Italian energy and environment organization) and DPC. Recently the strong-motion data relative to the 23th December 2009, Parma (Mw = 5.4 and Mw = 4.9) and to the April 2009 L’Aquila sequences (13 earthquakes with 4.1 ≤ Mw ≤ 6.3) were included in the Italian Accelerometric Archive (ITACA) database (beta release). The database contains 7,038 waveforms from analog and digital instruments, generated by 1.019 earthquakes with magnitude up to 6.9 and can be accessed on-line at the web site . The strong motion data are provided in the unprocessed and processed versions. This article describes the steps followed to process the acceleration time series recorded by analogue and digital instruments. The procedures implemented involve: baseline removal, instrumental correction, band pass filtering with acausal filters, integration of the corrected acceleration in order to obtain velocity and displacement waveforms, computation of acceleration response spectra and strong motion parameters. This procedure is applied to each accelerogram and it is realised to preserve the low frequency content of the records.  相似文献   

Thank you to 2022 Ocean Dynamics reviewers     

Ezer  Tal  Carniel  Sandro  Amin  Chabchoub  de Camargo  Ricardo  Estrada-Allis  Sheila N.  Gao  Guoping  Greatbatch  Richard J.  Lermusiaux  Pierre F. J.  Liu  Zhiyu  Miyazawa  Yasumasa  Forster  Alejandro Orfila  Panickal  Swapna  Phillips  Helen  Pinones  Andrea  Stanev  Emil  Volker  Christoph  Xu  Fanghua  Young  Emma 《Ocean Dynamics》2023,73(1):35-38

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A lumped parameter model for time‐domain inertial soil‐structure interaction analysis of structures on pile foundations          下载免费PDF全文

Sandro Carbonari  Michele Morici  Francesca Dezi  Graziano Leoni 《地震工程与结构动力学》2018,47(11):2147-2171

The paper presents a lumped parameter model for the approximation of the frequency‐dependent dynamic stiffness of pile group foundations. The model can be implemented in commercial software to perform linear or nonlinear dynamic analyses of structures founded on piles taking into account the frequency‐dependent coupled roto‐translational, vertical, and torsional behaviour of the soil‐foundation system. Closed‐form formulas for estimating parameters of the model are proposed with reference to pile groups embedded in homogeneous soil deposits. These are calibrated with a nonlinear least square procedure, based on data provided by an extensive non‐dimensional parametric analysis performed with a model previously developed by the authors. Pile groups with square layout and different number of piles embedded in soft and stiff soils are considered. Formulas are overall well capable to reproduce parameters of the proposed lumped system that can be straightforwardly incorporated into inertial structural analyses to account for the dynamic behaviour of the soil‐foundation system. Some applications on typical bridge piers are finally presented to show examples of practical use of the proposed model. Results demonstrate the capability of the proposed lumped system as well as the formulas efficiency in approximating impedances of pile groups and the relevant effect on the response of the superstructure.  相似文献   

Spatial modeling of pyroclastic cover deposit thickness (depth to bedrock) in peri‐volcanic areas of Campania (southern Italy)          下载免费PDF全文

Matteo Del Soldato  Veronica Pazzi  Samuele Segoni  Pantaleone De Vita  Veronica Tofani  Sandro Moretti 《地球表面变化过程与地形》2018,43(9):1757-1767

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On the influence of etch pits in the overall dissolution rate of apatite basal sections     

Igor Alencar  Sandro Guedes  Rosane Palissari  Julio C. Hadler 《Physics and Chemistry of Minerals》2015,42(8):629-640

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