La répartition del glissements de terrain dans les Carpates Orientales (zone du flysch)

The distribution of landslides in Eastern Carpathians (flysch zone)

Abstract

The research came as a remark upon the repartition of the landslides in flysch mountains. We took into consideration those landslides which were active after the last major cycle of humidity excess, namely the period between 1970-1974. Five hundred landslides were monitorised and their distribution was analyzed according with their distribution in space and altitude. In this area several correlations have been settled between the extent of some lithological entities, the frequency of slidings, the volume of the moving deluvium and the new morphology that has been created. It can be noticed that 70% of the landslides and 90% of the volume of the deluvium which has been set afoot, have been registered where cla3′s, clays with marl intercalations, marn-limestones and sandstones are predominant. As a result of the slopes evolution in time, in relation with lithology, and of the human actions for their stabilization, it has been found that landslides appear between 400 and 900 meters absolute altitude. In the last cycle of recrudescence, the most labile altitudinal areas were those ones between 500 and 600 m (29% of the total volume set afoot), where deepest anthropic actions had taken place and between 700-800 m (30% of the total volume) where landslides appeared as a «reply» of the irregularities of the previous cycle. In the future, because of the lability of these zones, the extension of deforested areas, the exploitation of subsoil minerals and the constructions of roads, the major landslides will appear between 1100 and 1200 m. The final part of the study suggests an evolution model of the slopes in flysch mountains by sliding processes.