Deformation characteristics and multi-slab formation of a deep-seated rock slide in a high alpine environment (Bliggspitze, Austria)

Abstract

This study presents the results of a more than 10-year-long field investigation and remote sensing monitoring campaign of a highly active deep-seated rock slide located in a glacial to periglacial environment (Bliggspitze, Tyrol, Austria). Data concerning (i) the terrain surface displacements based on imagery (webcam time-lapse, ortho-images) and both terrestrial and airborne laser scanning, and (ii) the geological-structural and geomorphological situation were analysed to develop a geological-geometrical model of the rock slide and to study the temporally variable activity behaviour and the formation of individual rock slide slabs. Results clearly show that at least seven rock slide slabs were formed at different times and under different slope stability conditions. Some of these rock slide slabs were displaced at slow to moderate velocities and reached scarp offsets of several tens of metres, whereas other, shallower slabs collapsed and formed extremely rapid rock falls and avalanches. Generally, the rock slide is affected by rock mass cataclasis, fracturing and loosening, which in turn cause extensive mass loss accompanied by debris accumulation at lower parts of the slope. The cause for the development of the Bliggspitze rock slide is poorly understood. However, there are clear indications that permafrost degradation and/or glacial retreat, particularly at the foot of the slide, during the recent decades may have adversely affected the slope stability situation. Keywords Deep-seated rock slide . Metamorphic rock . Rock slide slab formation . High alpine environment . Glacial changes . Remote sensing . Monitoring . Airborne and terrestrial laser scanning * C. Zangerl

Monitoring and analysis of the exceptional displacements affecting debris at the top of a highly disaggregated rockslide

“…A proper understanding of what these may represent in terms of the overall slope dynamics is necessary to reduce incorrect alarms. Recent examples of rockslide characterization through the analysis of surface displacement data are provided in Bonzanigo et al (2007), Barla et al (2010), Crosta et al (2014), Palis et al (2017), and Zangerl et al (2019).…”

An integrated approach to investigate climate-driven rockfall occurrence in high alpine slopes: the Bessanese glacial basin, Western Italian Alps

“…Despite the remarkable efforts and the significant advances, uncertainties remain as to how climatic parameters control rockfall occurrence and therefore on the actual impacts of ongoing and expected climate change on rock slope instability (Huggel et al 2012), in particular, considering the complexity of processes contributing to slope stability/instability and the interactions with the specific morphotopographical and litho-structural conditions of the study areas (Phillips et al 2017;Messenzehl et al 2017;Zangerl et al 2019). Specifically, the question remains whether the climate change has actually caused, and/or may in the future, an increase, or change, of rockfall hazard in high mountains, even though several evidences point in this direction (Ravanel and Deline 2011;Fischer et al 2012).…”

The Status of Earth Observation Techniques in Monitoring High Mountain Environments at the Example of Pasterze Glacier, Austria: Data, Methods, Accuracies, Processes, and Scales

“…High mountain applications have been a frequent scope in the usage of TLS such as monitoring rock faces [39][40][41][42], sediment budgets [43], the evolution of paraglacial areas [44] and subsequent slope instabilities [45], the characterization of rock glaciers [46,47], or snow applications [36]. First long-term measurements on Austrian glaciers were carried out by Bauer et al [48] at Gössnitzkees (Schober Mountains, Austria), Avian et al [49] on Pasterze Glacier, and Stötter et al [50] in Tyrol (e.g., Hintereisferner).…”