Assessing the effect of lithological setting, block characteristics and slope topography on the runout length of rockfalls in the Alps and on the island of La Réunion

Abstract

Abstract. In four study areas within different lithological settings and rockfall activity, lidar data were applied for a morphometric analysis of block sizes, block shapes and talus cone characteristics. This information was used to investigate the dependencies between block size, block shape and lithology on the one hand and runout distances on the other hand. In our study, we were able to show that lithology seems to have an influence on block size and shape and that gravitational sorting did not occur on all of the studied debris cones but that other parameters apparently control the runout length of boulders. Such a parameter seems to be the block shape, as it plays the role of a moderating parameter in two of the four study sites, while we could not confirm this for our other study sites. We also investigated the influence of terrain parameters such as slope inclination, profile curvature and roughness. The derived roughness values show a clear difference between the four study sites and seem to be a good proxy for block size distribution on the talus cones and thus could be used in further studies to analyse a larger sample of block size distribution on talus cones with different lithologies.

Model Test Study on Rock Rolling Characteristics

“…The current research methods related to the characteristics of rockfall movement mainly include theoretical derivation [4], model experiments [5][6][7][8], numerical simulations [9][10][11][12], and mathematical probability models for data analysis and statistics of historical rock collapse events [13][14][15]. Theoretical derivation typically relies on kinematic principles and contact mechanics to derive the trajectory of a falling rock.…”

“…Cui et al [17] established a model for the oblique throwing and impact of falling rocks, allowing for the calculation of movement distance and impact force. Yang et al [18] considered the influence of the rotational inertia of rockfalls, dividing the motion The current research methods related to the characteristics of rockfall movement mainly include theoretical derivation [4], model experiments [5][6][7][8], numerical simulations [9][10][11][12], and mathematical probability models for data analysis and statistics of historical rock collapse events [13][14][15]. Theoretical derivation typically relies on kinematic principles and contact mechanics to derive the trajectory of a falling rock.…”