29 research outputs found
The temporal stability and activity of lansdlides in Europe with respect to climatic change: TESLEC, programme DG XII
Final National Repor
EC-Programme NEWTECH "New technologies for landslide hazard assessment and management in Europe: European Coimmission, Brussels
Intermediate Repor
Landslides and climatic conditions in Barcelonnette and Vars Basin (Southern Alps, France).
International audienc
The 3-D structure of the Super-Sauze earthflow (Alpes-de-Haute-Provence, France) : a first stage toward modelling its behaviour
International audienc
Integrated investigations on landslides: example of the Super-Sauze earthflow
International audienc
EC-Programme NEWTECH "New technologies for landslide hazard assessment and management in Europe: European Commission, Brussels
Final National Repor
Surface morphology of quartz grains from tropical soils and its significance for assessing soil weathering
The surface morphology of quartz grains can indicate the degree of weathering of soil material. We have compared two methods of assessing the relative weathering of soils on the basis of differences in the surface morphology of quartz sand grains in a catena of soils in Rwanda. One method is based on the presence or absence of surface features indicative of weathering or freshness, while the other uses the frequency and size of dissolution etch pits. A ranking of relative weathering could be obtained using the first technique for the slightly and somewhat weathered soils but not for the weathered soils. On the other hand, weathering trends and differences between the horizons studied were detected in weathered soils using the second method. The introduction of more specific definitions of the weathering classes used in the latter method leads to clear improvement of the inter-observer reproducibility of the weathering classification.
The surface features on the quartz grains suggest that the soil at the summit is less weathered than the other soils of the sequence. Quartz grains from the well-drained soils on the slopes, which are subjected to more intense leaching and thus to stronger chemical weathering, have more triangular etch pits and chatter marks. In the imperfectly drained soils in the valley bottom quartz grains are less etched because dissolution is inhibited by the oversaturation in silica of the drainage waters
Une approche multidisciplinaire pour la connaissance dâun glissement-coulĂ©e dans les marnes noires du Callovien-Oxfordien
Dans le bassin de Barcelonnette, le glissement-coulĂ©e de Super-Sauze sâest dĂ©veloppĂ© dans un bassin torrentiel de marnes noires callovo-oxfordiennes Ă©rodĂ© en ravines et Ă©chines coaslescentes. Sur ce site naturel, mais complexe et difficile dâaccĂšs, une approche multidisciplinaire a associĂ© une analyse gĂ©omorphologique couplĂ©e Ă un traitement photogrammĂ©trique numĂ©rique, une prospection gĂ©otechnique (sondages et essais in situ et en laboratoire) et une investigation gĂ©ophysique (mĂ©thodes de mesure de la rĂ©sistivitĂ© Ă©lectrique (Ă©lectrique par courant continu et TDEM-time-domain electro-magnetism), sismique rĂ©fraction, Slingram. Les comparaisons, ajustements, validations des rĂ©sultats complĂ©mentaires ont permis de reconstituer lâĂ©volution historique du mouvement, de proposer un modĂšle conceptuel dâĂ©volution, de dĂ©finir la position et forme de la paiĂ©otopographie, la structure interne de la coulĂ©e de dĂ©bris dans la zone dâaccumulation et dans la zone dâablation avec des ordres de grandeur de prĂ©cision tout Ă fait satisfaisants. Il est maintenant possible dâenvisager la modĂ©lisation du comportement dynamique de ce type de coulĂ©e de dĂ©bris, frĂ©quent dans les Terres noires (thĂšse J.-P. Malet en cours) en relation avec les conditions hydrodynamiques. Lâobjectif est dâĂ©valuer la probabilitĂ© de transformation rapide, de tout ou partie de la masse instable, en coulĂ©es boueuses ou en laves torrentielles