| Summary: | Active rock glaciers are the manifestation of creeping mountain permafrost, which has received considerable attention for its current dynamical changes reported mainly from the European Alps. Rock glacier kinematics have traditionally been quantified by repeated in-situ point measurements and, more recently, by remote sensing approaches. Repeated point measurements, though, do not capture the high spatial variability of the rock glacier deformation processes. Recent developments in the field of Uncrewed Aerial Vehicles (UAV) systems and digital photogrammetry are providing an upsurge of very high-resolution spatial data, together with the enhancement of computer processing and acquisition procedures. However, the benefits and weaknesses associated with close and remote sensing techniques and the accuracy of the high-resolution sensing techniques on rock glacier surfaces have not yet been systematically investigated. Close-range sensing techniques have been employed to study surface displacements and elevation changes in the Tsarmine rock glacier since 2016. For independent validation of the UAV-derived kinematic data, the displacement of several boulders was measured by repeated GNSS surveys. Additionally, several UAV surveys and webcam devices were employed to monitor the destabilization phase of a previously unknown rock glacier. Using a combination of high-density point clouds and co-registration techniques, elevation and volumetric changes were quantified in very-high detail at La Roussette rock glacier. Annual UAV surveys since 2016 were employed to study the kinematics and elevation changes on three dissimilar rock glaciers. The results point toward different mass redistribution processes and activity phases. In light of the developments achieved by using repeated UAV surveys to estimate volume change, further recommendations are made to assess the annual rock glacier mass budget. In the Dry Andes, rock glacier kinematics were studied using archival aerial photographs and recent satellite imagery together ...
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