Guidelines for the selection of appropriate remote sensing technologies for landslide detection, monitoring and rapid mapping: the experience of the SafeLand European Project.

New earth observation satellites, innovative airborne platforms and sensors, high precision laser scanners, and enhanced ground-based geophysical investigation tools are a few examples of the increasing diversity of remote sensing technologies used in landslide analysis. The use of advanced sensors and analysis methods can help to significantly increase our understanding of potentially hazardous areas and helps to reduce associated risk. However, the choice of the optimal technology, analysis method and observation strategy requires careful considerations of the landslide process in the local and regional context, and the advantages and limitations of each technique. Guidelines for the selection of the most suitable remote sensing technologies according to different landslide types, displacement velocities, observational scales and risk management strategies have been proposed. The guidelines are meant to aid operational decision making, and include information such as spatial resolution and coverage, data and processing costs, and maturity of the method. The guidelines target scientists and end-users in charge of risk management, from the detection to the monitoring and the rapid mapping of landslides. They are illustrated by recent innovative methodologies developed for the creation and updating of landslide inventory maps, for the construction of landslide deformation maps and for the quantification of hazard. The guidelines were compiled with contributions from experts on landslide remote sensing from 13 European institutions coming from 8 different countries. This work is presented within the framework of the SafeLand project funded by the European Commission’s FP7 Programme.JRC.H.7-Climate Risk Managemen

ÉTUDE THÉORIQUE DES RÉACTIONS D'OLIGOMÉRISATION DES OLÉFINES CATALYSÉES PAR DES COMPLEXES DU FER

Iron-bis(imino)pyridine catalysts are highly active in olefins oligo- or polymerization reactions. IFP notably wishes to study these catalysts to transform ethyleneinto linear olefins with specified chain length. However, the precursor activation step (usually with the MAO cocatalyst) generates an activated species in which the precise nature of the iron metal ion remains largely unknown. Our DFT calculations show that the most reactive activated species likely has an oxidation state +III and quartet spin state. The fact that our DFT calculations in combination with a microkinetic model describe accurately the experimental results of the oligomerization of 1-butene, i.e., the principal formation of linear octenes, furnishes additional support for the retained active species. Moreover, using this molecular representation, a powerful relation has been established between the Schulz-Flory coefficient, which informs of experimental oligo- or polymerization degree for a catalyst, and the difference in the Gibbs free activation energy of a typical insertion and termination reaction. This relation has allowed us to study and better understand the particular behaviour of iron-bis(arylimino)pyridine catalysts with respect to substituents changes. Moreover, its strong universal potential has been shown with the extension of its application domain to other catalysts (other ligands, other metals). Finally, the agostic bonds in bis(arylimino)pyridine complexes have been studied by QTAIM calculations, because this bond type is often a prelude to termination reactions in catalytic cycles.Les catalyseurs bis(imino)pyridine au fer sont hautement actifs en oligo- ou polymérisation des oléfines. L'IFP souhaite étudier ces catalyseurs pour transformer l'éthylène en oléfines linéaires de tailles maîtrisées. Cependant, l'étape d'activation du précurseur (usuellement avec le cocatalyseur MAO) génère une espèce activée dont la nature reste à ce jour inconnue. Nos calculs DFT montrent que l'espèce activée la plus réactive est dans un état d'oxydation +III et de spin quadruplet. Le fait que nos calculs, en combinaison avec un modèle microcinétique, décrivent précisément les résultats expérimentaux d'oligomérisation du butène-1, c'est-à-dire la formation majoritaire d'octènes linéaires, fournit un support additionnel à la pertinence de l'espèce activée retenue. Par ailleurs, l'utilisation de ce modèle moléculaire a permis d'établir une puissante corrélation entre le coefficient Schulz-Flory, qui informe du degré d'oligo- ou de polymérisation expérimental d'un catalyseur, et la différence des enthalpies libres d'activation d'une réaction d'insertion et de terminaison particulières. Cette relation nous a permis d'étudier et de mieux comprendre le comportement des catalyseurs bis(arylimino)pyridine au fer vis-à- vis des changements de substituants. En outre, son fort potentiel universel est montré grâce à l'extension de son domaine d'application vers d'autres catalyseurs (autres ligands, autres métaux). Enfin, les liaisons agostiques dans les complexes bis(arylimino)pyridine ont été étudiées par des calculs QTAIM parce qu'elles sont souvent un prélude aux réactions de terminaison dans les cycles catalytiques

Mechanical properties of icosahedral boron carbide explained from first principles

International audienceAn exhaustive study of the neutral structural defects of icosahedral B4C has been performed with the density functional theory. Vacancies have been determined to be boron vacancies in the C-B-C chains. Their presence is shown to yield a discontinuous variation of crystal volume upon increasing pressure, when the formation of a C-C bond occurs in the chains. The dynamical failure of shocked B4C is attributed to the formation of these C-C bonds

Synthesis of New RuO2@SiO2 Nanomaterials and their Application as Catalytic Filters for Selective Gas Detection

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Subsidence in the Athens basin monitored by INSAR

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Subsidence monitoring within the Athens Basin (Greece) using space radar interferometric techniques

The application of conventional SAR Interferometry (InSAR) together with the two techniques of sub-centimeter accuracy, the Stacking and the Permanent Scatterers (PS) Interferometry, were used to study the ground deformation in the broader area of Athens for the period 1992 to 2002. Using the Stacking interferometric method, 55 ERS-1&2 SAR scenes, between 1992 and 2002, were acquired producing 264 differential interferograms. Among these only 60 were finally selected as fulfilling certain criteria. The co-seismic deformation associated with the Athens Earthquake (Mw = 5.9, September 7, 1999) was excluded from the analytical procedure in an attempt to present results of only aseismic character. In total ground subsidence results of about 12 mm in the southern suburbs of Athens, but higher value of about 40 mm in the northern ones for the period 1992-2002. Based on the PS technique, a precise average annual deformation rate-map was generated for the period 1992-1999, ending just before the Athens earthquake event. Both circular and elongated-shape areas of subsidence are recognizable especially in the northern part of the Athens Basin (3-4 mm/yr), as well as at its southern part (1-3 mm/yr). In addition, a rate of 2-3 mm/yr is also yielded for some part of the Athens city center. Subsidence rates of 1-2 mm/yr are measured at the western part of the basin over an area of old mining activities, and around the newly built Syntagma Metro Station. The correlation of the observed deformation patterns with respect to the spatial distribution of water pumping, older mining activities, metro line tunneling and other local geological parameters is examined and discussed. Copyright © The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences; TERRAPUB

Subsidence monitoring within the Athens basin (Greece) using space radar interferometric techniques

International audienceThe application of conventional SAR Interferometry (InSAR) together with the two techniques of subcentimeter accuracy, the Stacking and the Permanent Scatterers (PS) Interferometry, were used to study the ground deformation in the broader area of Athens for the period 1992 to 2002. Using the Stacking interferometric method, 55 ERS-1&2 SAR scenes, between 1992 and 2002, were acquired producing 264 differential interferograms. Among these only 60 were finally selected as fulfilling certain criteria. The co-seismic deformation associated with the Athens Earthquake (Mw = 5.9, September 7, 1999) was excluded from the analytical procedure in an attempt to present results of only aseismic character. In total ground subsidence results of about 12 mm in the southern suburbs of Athens, but higher value of about 40 mm in the northern ones for the period 1992-2002. Based on the PS technique, a precise average annual deformation rate-map was generated for the period 1992-1999, ending just before the Athens earthquake event. Both circular and elongated-shape areas of subsidence are recognizable especially in the northern part of the Athens Basin (3-4 mm/yr), as well as at its southern part (1-3 mm/yr). In addition, a rate of 2-3 mm/yr is also yielded for some part of the Athens city center. Subsidence rates of 1-2 mm/yr are measured at the western part of the basin over an area of old mining activities, and around the newly built Syntagma Metro Station. The correlation of the observed deformation patterns with respect to the spatial distribution of water pumping, older mining activities, metro line tunneling and other local geological parameters is examined and discussed

Suivi de la subsidence dans le bassin d'Athènes (Grèce) par des techniques d'interferométrie radar spatiale

International audienceThe application of conventional SAR Interferometry (InSAR) together with the two techniques of sub-centimeteraccuracy, the Stacking and the Permanent Scatterers (PS) Interferometry, were used to study the ground deformation in the broader area of Athens for the period 1992 to 2002. Using the Stacking interfero-metricmethod, 55 ERS-1&2 SAR scenes, between 1992 and 2002, were acquired producing 264 differential interferograms. Among these only 60 were finally selected as fulfilling certain criteria. The co-seismic deforma-tionassociated with the Athens Earthquake (Mw = 5 9, September 7, 1999) was excluded from the analytical procedure in an attempt to present results of only aseismic character. In total ground subsidence results of about12 mm in the southern suburbs of Athens, but higher value of about 40 mm in the northern ones for the period 1992-2002. Based on the PS technique, a precise average annual deformation rate-map was generated for the period 1992-1999, ending just before the Athens earthquake event. Both circular and elongated-shape areas of subsidence are recognizable especially in the northern part of the Athens Basin (3-4 mm/yr), as well as at its southern part (1-3 mm/yr). In addition, a rate of 2-3 mm/yr is also yielded for some part of the Athens city center. Subsidence rates of 1-2 mm/yr are measured at the western part of the basin over an area of old mining activities, and around the newly built Syntagma Metro Station. The correlation of the observed deformation pat-ternswith respect to the spatial distribution of water pumping, older mining activities, metro line tunneling and other local geological parameters is examined and discussed