1,721,227 research outputs found
Landlside back monitoring and forecasting by using psinsar technique: The case of naso (Sicily, Southern Italy)
Full text linkLandlside back monitoring and forecasting by usingPSInSAR: Technique: The case of Naso (Sicily, southern Italy). The village of Naso (Sicily, southern Italy), for its peculiar geological setting, was affected by several landslide phenomena (rockfalls, complex landslides) during the first months of the 2010. The village is located on top of hard-brittle Quaternary deposits (calcareous sandstones), lying on a soft-plastic substratum. These phenomena represent a serious risk for the buildings stability and people safety. In order to study the slope instability evolution of this area, satellite Synthetic Aperture Radar (SAR) images, acquired during the last 20 years, have been processed and analyzed. These data have been acquired by using C-band and X-band sensors. Results highlighted that the 2010 events was preceded by several acceleration periods and that the slope is still affected by ground deformation
Two GUIs-based analysis tool for spectroradiometer data pre-processing
No full textA new graphical user interface (GUI) for pre-processing reflectance spectra, built using MATLAB and expressly designed for the ASD FieldSpec® spectroradiometer, was developed to solve problems that generally affect experimental ASD data. The GUI is characterised by an easily readable, graphic visualisation of spectra, from which the absorption band depth (ABD) can be obtained for a selected wavelength. The output format of the ASD data is a binary file with an .asd extension. The binary file, that provides a single spectrum, can be processed using a software functionality, by means of a GUI, that allows to select one or more binary files to produce a spectral library in a unique .txt file. The spectral reflectance is re-calibrated with the "convex-hull" methodology to eliminate the convex shape, which is typical of reflectance spectra. Different examples of the use of the new GUI are provided. © 2013 Springer-Verlag Berlin Heidelberg
Remote sensing techniques using Landsat ETM+ applied to the detection of iron ore deposits in Western Africa
No full textRemote sensing methods enable the rapid and inexpensive mapping of surface geological and mineralogical features. This capability proves highly useful when working on isolated or inaccessible areas. In this study, several enhancements of Landsat Enhanced Thematic Mapper plus (i.e. band ratios, false colour composites and principal component analysis) were used and evaluated to obtain the best possible visualisation of iron deposits hosted in the Devonian sedimentary rocks of northwestern Africa. In particular, two test sites were chosen: southern Algeria (Djebilet area), where the literature mineralogical and geological data on iron mine fields were already available, and the Western Sahara (the southern flank of Tindouf Basin), which was investigated during a field campaign and was where the occurrence of an analogous sedimentary succession led us to hypothesise the possible presence of exploitable iron deposits. This work demonstrates the usefulness of multispectral imagery in the detection of iron-rich areas and establishes a full remote sensing procedure, which can be profitably applied to a wider region of Western Sahara and can provide interesting perspectives on the possibility of detecting new exploitable iron ore deposits in arid environments. © 2012 Saudi Society for Geosciences
Quantitative mapping of clay minerals using airborne imaging spectroscopy: New data on mugello (Italy) from SIM-GA prototypal sensor
Full text linkThe possibility of using high spectral and spatial resolution remote sensing technologies is becoming increasingly important in the monitoring of soil degradation processes. A high spatial resolution hyperspectral dataset was acquired with the airborne Hyper SIM-GA sensor from Selex Galileo, simultaneously with ground soil spectral signatures and samples collection. A complete mapping procedure was developed using the 2000-2450 nm spectral region, demonstrating that the 2200 absorption band allows the obtainment of reliable maps of the clay content. The correlation achieved between the observed and the predicted values is encouraging for the extensive application of this technique in soil conservation planning and protection actions
Potential Use of Remote Sensing Techniques for Exploration of Iron Deposits in Western Sahara and Southwest of Algeria
No full textAt 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. © 2013 International Association for Mathematical Geology
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Evaluation of subsidence induced by long-lasting buildings load using InSAR technique and geotechnical data: The case study of a Freight Terminal (Tuscany, Italy)
Full text linkThis paper shows the results of the comparison between Multi-temporal Synthetic Aperture Radar (MTInSAR) products derived from different sensors (C-band ERS 1/2, Envisat, Sentinel-1 and X-band COSMO-SkyMed) and geotechnical data to investigate the driving factors of subsidence which affect a freight terminal located along the a coastal plain of Tuscany (central Italy). MTInSAR data have been acquired in a very long period, between 1992 and 2018 and were analyzed in terms of subsidence rates and deformation time series at building scale. The obtained results show that the oldest buildings are still affected by a deformation rate close to −5 mm/yr, whereas recent buildings register rates around −40 mm/yr. Time series of deformation suggest that the deformation rates decrease over time following time-dependent trend that approximates the typical consolidation curve for compressible soils. The geotechnical and stratigraphical analysis of the subsurface data (boreholes, cone penetration tests and dilatometer tests) highlights the presence of a 15 m thick layer formed of clay characterized by poor geotechnical characteristics. The comparison among InSAR data, subsurface geological framework and geotechnical reconstruction suggests a possible evaluation of the timing of the primary and secondary consolidation processes
PSInSAR analysis in urban areas: A case study in the Arno coastal plain (Italy)
No full textThe Permanent Scatterer Interferometry (PSI) has been used to detect the land subsidence of the Arno coastal plain, in particular within the urban area of the city of Pisa. Two satellite PSInSAR dataset (ERS 1/2 and Envisat) were used to quantify the spatial evolution of ground displacements. A set of 92 geotechnical borehole was also analyzed to relate the measured displacements with the local stratigraphic asset. Furthermore, the results of the interferometric data analysis were compared with the urban development, from1978 to 2013, of the eastern part of Pisa. The PSInSAR data show that the city of Pisa is divided in two sectors with different subsidence rates: the south - western part, with null or very small movements, and the eastern part that shows a general lowering with maximum velocities of 5 mm/yr. In the eastern part, single or small groups of buildings recorded subsidence rates higher than 15 mm/yr. Through the analysis of the temporal evolution and magnitude of the subsidence rates recorded by several buildings in these areas, the importance of the urbanization as an accelerating factor for the consolidation process have been demonstrated
Combining biodiversity and geodiversity on landscape scale: A novel approach using rare earth elements and spatial distribution models in an agricultural Mediterranean landscape
Full text linkLandform diversity influences and interacts with both biodiversity and geodiversity and thus, they are key factors in the assessment of landscape resilience. However, research on the spatial relationships between landscape geodiversity and biodiversity is challenging because we are still lacking methods to link abiotic with biotic factors. The goal of this study is to explore and quantitatively assess the spatial relationship between geomorphometric factors and the relative distribution of rare earth elements (REEs) in soils and organism. Therefore, we selected a representative Mediterranean landscape characterized by ancient olive grove cultivations. The results show for different landforms and lithotypes a positive linear correlation in the lanthanum/samarium vs. lanthanum/ytterbium (La/Sm vs. La/Yb) signature between the bioavailable fraction of topsoil and olive drupe. Results of La/Yb vs. La/Sm reported as power function for olive drupes and topsoil follow comparable scaling ranges showing a power law of 0.83 and 0.71 respectively with an R2 0.96 vs. 0.71. A different scaling range behavior from topsoil to the related olive drupe was found for each parent rock material. Results of the Machine Learning (ML) modelling framework showed that the LaN/SmN in topsoil, were substantiality correlated to channel network base level, topographic wetness index, NDWI and valley depth. Under the physiographic environmental variables of the study area, the spatial distribution of LaN/YbN was mainly related to the lithological characteristics. Furthermore, NDVI was the most important variable to predict the fractionation ratio of LaN/YbN in olive drupe and the topographic channel network distance for LaN/SmN in olive drupe. Our findings provide new insights in the spatial distribution of REEs allowing an assessment of bio- and geodiversity of olive groves taking into account biophysical factors. Our research represents a starting point for future applications and modelling techniques to analyze at the catchment-scale the REEs biophysical fluxes and food traceability
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