Crumbling Mountains: Pre-failure and failure analysis of the 2024 Permafrost Rock Slide and bifurcated Rock Avalanche (Platteikogel, Austria)

Glacier retreat and permafrost warming amplify geomorphological activity, increase rockfall frequency, and contribute to the preparation or triggering of rock slides and rock avalanches, often involving millions of cubic meters of material. However, high-magnitude rock slides situated in the cryosphere are rarely anticipated, primarily due to the remoteness and inaccessibility of the terrain, leaving pre-failure activity undocumented. Such events typically gain attention only after the occurrence, often due to the transition into long-runout rock avalanches that visibly impact large areas, potentially endangering alpine communities several kilometers distant from the rock slide source zone. The glaciated Vernagtferner basin (Austria, Tyrol) is a prime location for glaciology research, offering abundant data to also study the interactions between changing cryosphere and mass movements. It features highly weathered metamorphic rock slopes, ridges, and peaks, making it an exemplary site for studying typical alpine permafrost morphology and landslide processes. In this study, we characterize the geomorphic activity of the Vernagtferner basin through a landslide catalog and erosion rates assessed in three-year intervals from 2015 to 2024. Ultimately, we investigate the event of a recent rock slide/rock avalanche in spring 2024, originating from a permafrost ridge at 3,395 m asl, with over 50,000 m³ of volume loss in the source zone. The event exhibited an extended runout over snow and glacier surfaces. We combine seismic analysis, meteorological records, permafrost modeling, and rock mechanical modeling to identify the preparatory factors. With numerous potential failure sites distributed over vast areas and complex failure processes, spatial-scale rock slide prediction remains challenging today. Therefore, we focused on deciphering past events and the processes leading to them. This study's preliminary results help improve future predictive capabilities and mitigate increasing risks.