Dynamics, conditioning factors and possible causes of the formation of the Tartera de Cambrils (Solsonès, Lleida)

Abstract

Landslides and rockfalls are a common hazard in mountain areas like the Pyrenees. However, due to the difficulty of access and therefore of data acquisition, and the low density of population they are poorly studied. The Tartera de Cambrils, is located in a small town in the Solsonès region, Catalonia, and is the product of ancient landslides and succeeding rockfalls. These processes can endanger different infrastructures in the village of Cambrils such as the road, the sports centre, the salt flats called “El Salí” (currently also being used for tourist activity), two inns and several houses. This study aims to determine the processes that caused the initial landslides, those that occur at the rock slope nowadays and their causative factors. For this, we compiled information from the literature, conducted a field study building a geologic and geomorphologic cartography and acquired LiDAR data, with a Terrestrial Laser Scan, and photographs in order to produce three-dimensional point clouds. We also analyse the rock-cliff stability using photogrammetry and LiDAR data and direct measures of rock mass discontinuities. The bedding dips smoothly and contrary to the slope, making planar sliding an unprovable mechanism, favouring wedge sliding and toppling. The rock discontinuities are the main causative factor of rockfalls. Rockfall originates from rock fronts of decametric volume along the main scarp and on the scree. These rock fronts rotated respect to the rock in situ. The farther away from the main scarp, the larger the rotation of the blocks. The analysis of the fractures allows estimating an important possibility of rockfall directly affecting the inns and the road and provides fundamental data for the development of protection measures.