Tiziana Egli: Cartes de danger de chutes de blocs sur le village des Morgnes (Bagnes)

Tiziana Egli
Co-supervisors : Dr. Vincent Labiouse, Prof. Michel Jaboyedoff
Experts : Dr. François Joseph Baillifard, MSc. Clément Michoud

The alpine village of Les Morgnes is dominated by a long cliff. Some previous reports and blocks present in the forest below the cliff informs that the village is threatened by this cliff. The aim of this study is to establish the rockfall hazard map for this place combining two different methodologies: the Matterock approach and the CADANAV approach.

The studied cliff is located in an old glacial valley and it’s surrounded by landslides. The cliff is mainly composed by quartzite and past tectonic conditions has created a significant schistosity. According to the Matterock methodology, field campaigns and LiDAR scans establish the structural conditions and the potential localized sources. The susceptibility mapping was performed with a software according to kinematic tests. Toppling and wedge sliding are the principal failure mechanisms. 2D trajectography were simulated along predefined paths. The hazard assessment, based on the trajectography studies, demonstrate that no building is in a dangerous zone. According to the CADANAV approach, 3D trajectography studies were performed. The semi-automatic hazard assessment shows that depending on the return period, some buildings are located in a high danger zone.