EGU22-9344, updated on 09 Jan 2023
EGU General Assembly 2022
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Assessment of Rockfall Hazard and 3D Trajectography based on Slope and Structural Settings: Case Study in Les Fréaux, France

Tiggi Choanji1,3, François Noël1,4, Li Fei1, Chunwei Sun1, Charlotte Wolff1, Marc-Henri Derron1, Franck Bourrier2, Michel Jaboyedoff1, and Romain Gaucher5
Tiggi Choanji et al.
  • 1Institute of Earth Science, University of Lausanne, 1015 Lausanne, Switzerland
  • 2Université Grenoble-Alpes, INRAE, ETNA, 38000 Grenoble, France
  • 3Department of Geological Engineering, Universitas Islam Riau, 28125 Pekanbaru Riau, Indonesia
  • 4Geohazard and Earth Observation, The Geological Survey of Norway (NGU), 6315 Torgarden NO-7491 Trondheim, Norway
  • 5Service Ingénierie, Département des Hautes-Alpes, Gap, Provence-Alpes-Côte d’Azur, France

The case study is located in the municipality of Les Fréaux, France. The site consists of Cambrian-Ordovician of amphibolite and gneiss rock with complex structural geology that formed in mountainous and large valley with steep slopes and even overhanging rock walls. In this site, rockfall is a major hazard for access roads and houses.

To assess rockfall hazard in the vicinity of the elements at risk, LiDAR data have been analysed and field work done on site from 2020 to 2021.  Rockfall source areas were identified directly on 3D point clouds (PC) based on two criteria, which are large slope angles and kinematic analysis from structural identification of fault, folds and joints. Based on these source areas, several 3D point cloud trajectory models were processed using the freeware stnParabel, for various block diameters (d1, d2, d3) in order to determine the propagation and the probability of reaching the settlements or roads.

Preliminary simulation of trajectories based on several method of simulations results showed some potential directions are reaching the road and also leading to settlements.

How to cite: Choanji, T., Noël, F., Fei, L., Sun, C., Wolff, C., Derron, M.-H., Bourrier, F., Jaboyedoff, M., and Gaucher, R.: Assessment of Rockfall Hazard and 3D Trajectography based on Slope and Structural Settings: Case Study in Les Fréaux, France, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9344,, 2022.

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