1,721,010 research outputs found
C/X-band SAR interferometry used to monitor slope instability in Daunia, Italy
No full textThanks to the all-weather, day-night capability to detect and quantify accurately small ground surface deformations, Synthetic Aperture Radar (SAR) Interferometry (InSAR) techniques are attractive for landslide hazard investigations. In particular, multi-temporal InSAR techniques allow to detect and monitor millimetric displacements occurring on selected point targets exhibiting coherent radar backscattering properties (mainly buildings and other man-made structures). In the present work we apply the SPINUA (Stable Point INterferometry over Un-urbanised Areas) multi-temporal processing technique [1] to the Daunia region located in Southern Apennines, Italy. This region includes several small hill-top towns affected by slope instability problems and is of particular interest for the Civil Protection – Regione Puglia Authority, which is one of the end users of the deformation maps derived by multi-temporal interferometric analysis of satellite data. This site was already investigated in the past though interferometric analysis [2] by using ERS-1/2 SAR data provided by ESA. In this work we present results obtained by processing SAR data acquired by the ENVISAT ESA satellite (, medium spatial resolution) as well as by the TerraSAR-X satellite (X-band high resolution) launched by DLR in 2007. Thanks to the finer spatial resolution with respect to data, X-band InSAR applications appear very promising for monitoring single man-made structures (buildings, bridges, railways and highways) as well as areas where data show low PS density. This is the case, in particular, of the Daunia region which is scarcely urbanised. Indeed, the results obtained with X-band data suggest that many more man-made and natural targets behave as persistent scatterers than in . Moreover, thanks again to the higher resolution, it should be possible to infer reliable estimates of the displacement rates with a number of SAR scenes significantly lower than in within the same time span or by using more images acquired in a narrower time span. Finally, with shorter wavelengths the sensitivity to LOS displacements is increased together with the capability of detecting very low displacements rates (as the pre- and post-failure movements related to landslides are expected to be). The displacements maps obtained by processing both C- and X-band SAR data will be presented for a selected number of towns affected by slope instability. Results will be commented with particular attention paid to the advantages provided by the new generation of X-band high resolution space-borne SAR sensors
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
A Finite Element Analysis of the Brindisi di Montagna Scalo Earthflow (Basilicata, Southern-Italy) Engineering Geology for Society and Territory
No full textIn this paper a general Finite Element Method (FEM) analysis is presented for the
investigation of landslide mechanics behavior, including a non-linear constitutive model of
soils. Landslide body is modeled using FEM with 3D volume elements, with large strains
assumptions, and the soil mass properties are adopted according to the non-linear Drucker-
Prager material formulation. The remaining soil region is assumed as boundary constrains. A
special attention is devoted to the geometrical definition of the volume of the landslide body
and of the boundary surfaces, particularly the landslide sliding surface, and to the applied
loads. To this aim a specific pre-processor code is employed which is able to generate the
mesh and the input file for the FEM code. The performances of the approach have been
checked by using the test case of Brindisi di Montagna Scalo landslide. In this first approach
the results show that the methodology is powerful and can be used efficiently for the numerical
analysis of complex landslide configuration
Artificial neural networks and kriging method for slope geomechanical characterization
No full textIn this work, Multi Layer Perceptron Artificial Neural Networks (MLP ANNs) and Kriging method are applied for slope stability analysis. Both methods have been applied in order to evaluate detrital layer depth within a test site located in countryside of Capoterra (South Sardinia, Italy). Test site consists in a large area subjected to flooding and great magnitude debris flow events. Identified area stability and strength have been analysed by building a local geodatabase that allowed to perform a correlation analysis between depth of the detrital layers and respective geotechnical, geo-mechanical, hydraulic characteristics. Some other features regarding morphological, geological, structural, physiographic and vegetation settings have been considered. The comparison between the results obtained with the MLP ANNs and kriging method shows that the two methods can be applied to implement a realistic and accurate representation of the depth and geomechanical properties of incoherent deposits
Tectonic Stress as Possible Co-predisposing Factor for Landslides Along the Central Adriatic Coast of Italy
No full textThe central and southern Italian coast on Adriatic Sea is affected by several historically active large and deep-seated landslides. These during the latest decades involved important infrastructures, like the railway and the motorway along the coastline. These landslides were activated in overconsolidated silty clayey deposits of the foredeep domain. Here the position of the main landslides in relation to the position of the buried front of the Apennines is presented. This general early-stage analysis shows that there is an interesting correspondence between the main landslides and the advanced buried thrust of Apennine deposits. The work proposes some thoughts about this correspondence and the possible influence of tectonic tangential stresses as one of the predisposing factor in the activation of these landslides
Microseismicity and acoustic emission for landslide monitoring (North-East Italy)
No full textIn the North-East Italy, along the left side of the Tagliamento River, the area around an old road tunnel, named Passo della Morte, is involved in a Deep Seated Gravitational Slope Deformation. The most active blocks move up to 5 cm/year. The western part is moreover characterized by sub-vertical limestone layers and a dense system of discontinuities and fractures which create ideal conditions for rapid rock slope failure. High risk is represented by the interference with a national road and the Tagliamento River. A microseismicity and acoustic emission monitoring system was designed to monitor signals generated by rock slope deformation, in order to obtain informations about the rock slide mechanism, to recognize precursory phenomena or to provide precursory patterns. It is composed by a seismometer and a piezoelectric transducer. The amount of microseisms and acoustic emission detected by these instruments was analyzed and a close relation between them was found. The influence of precipitations in the rock mass deformation was evaluated and an evident correlation between precipitation and microseisms/acoustic emission was found
Earthquake Triggered Landslides: The Case Study of a Roadway Network in Molise Region (Italy)
No full textn this paper, a level II approach aimed at evaluating the impact of the triggering potential of seismic landslides on a regional roadway network is described. The case study is located within the Southern Apennines in Molise Region (Italy). A seismic vulnerability assessment through fragility curves was performed. Its capability to provide useful data in view of territory planning and/or emergency management was explored by means of the implementation in GIS environment
The Geomorphologic Survey as Tool to Support Risk Management After Landslide Reactivation: The Case Study of Sauna di Corniglio Landslide (Northern Apennines, Italy)
No full textVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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