Analysis of spatial and temporal evolution of the Brienz/Brinzauls deep-seated landslide, Switzerland

Large compound landslides show long-term evolution, which is characterized by non-steady velocities, sudden accelerations and potential failure events. Accurate data is hence important for the analysis and the interpretation of their kinematic behavior, as well as associated hazard potential. Remote sensing techniques have demonstrated to be a valid complement to standard in-situ monitoring. Here we show how frequent acquisitions with remote Remotely Piloted Aircraft Systems (RPAS) can be used to study large landslide complexes. We performed an extensive analysis at the Brienz/Brinzauls landslide complex, located in canton Graubünden (Switzerland), based on 20 photogrammetric flights acquired between 2018 and 2023. Dem-of-Differences (DoD) and displacements from Digital Image Correlation (DIC) are computed to reconstruct the spatial and temporal evolution of the surface changes. We compare the results with independent monitoring data, and we perform a strain analysis to highlight areas of strain accumulation and identify possible relationships between kinematic domains, geological boundaries, as well as tectonic structures and rock mass discontinuities. The aim of this contribution is to demonstrate how spatial and temporal resolution of the datasets might deeply influence the interpretation of displacements in complex landslide scenarios.