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.

In this study, the geomorphological evolution of an inner flank of the Cratère Dolomieu at Piton de La Fournaise/La Réunion was investigated with the help of terrestrial laser scanning (TLS) data, terrestrial photogrammetric images, and historical webcam photographs. While TLS data and the terrestrial images were recorded during three field surveys, the study was also able to use historical webcam images that were installed for the monitoring of the volcanic activity inside the crater. Although the webcams were originally intended to be used only for visual monitoring of the area, at certain times they captured image pairs that could be analyzed using structure from motion (SfM) and subsequently processed to create digital terrain models (DTMs). With the help of all the data, the geomorphological evolution of selected areas of the crater was investigated in high temporal and spatial resolution. Surface changes were detected and quantified on scree slopes in the upper area of the crater as well as on scree slopes at the transition from the slope to the crater floor. In addition to their quantification, these changes could be assigned to individual geomorphological processes over time. The webcam photographs were a very important additional source of information here, as they allowed the observation period to be extended further into the past. Besides this, the webcam images made it possible to determine the exact dates at which geomorphological processes were active.

In high mountain regions, rockfalls are common processes, which transport different volumes of material and therefore endanger populated areas and infrastructure facilities. In four study areas within different lithological settings, LiDAR (light detection and ranging) data were acquired for a morphometric analysis of block sizes, block shapes and talus cone characteristics. Based on these high-resolution terrestrial laser scanning (TLS) data, the three axes of every block larger than 0.5 m in the referenced point cloud were measured. Block sizes and shapes are used to investigate them in the context of runout distances and to analyse the spatial distribution of blocks on the talus cone. We also investigate the influence of terrain parameters such as slope inclination, roughness and profile curvature (longitudinal profiles). Our study shows that the relation of block size within different lithological settings on runout length is complex, because we can neither confirm nor reject the theory of gravitational sorting. We also found that the block shape (axial ratio) does not have a simple influence on runout length, as it plays the role of a moderating parameter in two study sites (Gampenalm: GA, Dreitorspitze: DTS) while we could not confirm this for Piton de la Fournaise (PF) and Zwieselbach valley (ZBT). The derived roughness values show a clear difference between the four study sites. This also applies for the parameter of slope inclination and longitudinal profiles.