Suchergebnisse

Territory — Boundaries — Tacit agreement — Unilateral recognition — Continuous, effective and uncontested exercise of sovereignty — Critical date — Natural frontiers — Watershed lineSources of international law — Protest and acquiescence — Estoppel — Acquiescence in boundary disputeStates — Federal States and confederations — Application of international law in dispute between two States within a confederation — Boundary dispute between two Swiss cantonsRelationship of international law and municipal law — Customary international law — Application of international law in disputes between Swiss cantons — The law of Switzerland

Abstract. About 22 mio m3 of rock fell from a cliff near the village of Randa (10 km north of Zermatt, Switzerland) on 18 April 1991. A second retrogressive rockslide of about 7 mio m3 followed on 9 May 1991. At present, a rock mass situated above the scarp is still slowly moving toward the valley, involving several mio m 3 of rock. A kinematic approach to study of this well-documented rockslide was made "a posteriori" in order to identify the parameters relevant to the detection of such failures involving large volumes of rock. A 3-D model of the pre-rockslide geometry is presented, and is used to interpret the geostructural, hydrogeological, and chronological data. The steepness of the cliff, the massive lithology (mainly orthogneiss), the location on a topographic ridge outcropping at the confluence between a glacial cirque and the main valley, and the existence of previous events of instability were the preexisting field conditions that affected the stability of the area. The structural cause of instability was a 30 dipping, more than 500-m-long, persistent fault, which cut the base of the rock face. Together with a steeply dipping set of persistent joints, this basal discontinuity delimited a 20- mio-m 3 rock block, with a potential sliding direction approximately parallel to the axis of the valley. To the North, the fractures delimiting the unstable mass were less persistent and separated by rock bridges; this rock volume acted as key block. This topographic and structural configuration was freed from glacier support about 15 000 years BP. The various mechanisms of degradation that led to the final loss of equilibrium required various amounts of time. During the late-and post-glacial periods, seismic activity and weathering of the orthogneiss along the fissure network due to infiltration of meteoric water, joined to reduce the mechanical resistance of the sliding surfaces and the rocks bridges. In addition, crystallisation of clay minerals due to mineralogical alteration of the fault gouge accumulated along the sliding surface, reducing its angle of internal friction, and sealing the surface against water circulation. Once this basal fracture began to act as an aquiclude, the seasonal increase of the hydraulic head in the fissures promoted hydraulic fracturing on the highly stressed edges of the key block. Acceleration of this mechanical degradation occurred during the 20-year period before the 1991 rockslides, giving rise to an increasing rockfall activity, that constituted a forewarning sign. The final triggering event corresponded to a snow-melt period with high water table, leading to fracturation around the key block. On 18 April 1991, the key block finally failed, allowing subsidiary orthogneiss blocks to slide. They fell in turn over a period of several hours. The 9 May 1991, rockslide was the first of a series of expected future retrogressive reequilibrium stages of the very fractured and decompressed paragneisses, which lie on the orthogneiss base cut by the 18 April event.

Aujourd'hui, un nombre grandissant de cantons suisses mettent en place des mesures incitatives pour encourager les fusions de communes. Ce travail vise tout d'abord à dresser un inventaire des bases légales fondant l'aide financière aux fusions dans les cantons concernés. Pour ce faire, nous avons recherché sur Internet des documents et avons croisé les résultats obtenus avec les informations fournies par les administrations cantonales. Dans une seconde phase, ce travail s'intéresse au point de vue des communes valaisannes par rapport aux incitations cantonales mises à leur disposition par l'Etat du Valais. Dans ce cadre, nous avons conduit des entretiens semi-directifs avec 13 présidents dont la commune a été récemment impliquée dans un processus de fusion. En 2011, 16 cantons suisses disposent d'un système d'incitations financières aux fusions de communes. 7 entre eux, dont une majorité romande, octroient ce soutien via un système de calcul. Les autres ont recours à un système de négociation. Au niveau du Valais, nos résultats tendent à montrer que l'aide financière est appréciée et considérée comme importante pour la réussite d'une fusion. Les interviewés ne considère pourtant pas qu'un soutien financier est décisif pour le lancement d'un processus de fusion ou pour le vote de la population. Ils estiment par ailleurs que les perspectives de bien-être sur le long terme pèsent plus que l'aide financière unique. Ainsi, la question de la péréquation financière devient un facteur essentiel à prendre en compte dans un système d'aide aux fusions. Pour le reste, les interviewés souhaitent que l'Etat du Valais définisse sa politique de fusions et ses objectifs d'une manière plus claire.