Rock slope response to contemporary deglaciation
Displacement fields measured on the Great Aletsch Glacier and Moosfluh rock slope instability using a portable radar interferometer.
“Climate change affects glaciated areas worldwide. Hazards associated with catastrophic landslides in recently de-glaciated valleys increasingly affect human society and critical infrastructure. Our study provides new insights in the interaction between deglaciation and rock slope response and is important for both scientific and practical reasons. We show that critically unstable slopes are sensitive to glacier ice loss, the slope response is significantly faster than previously reported, and landslide response brought on by rapid deglaciation may be enhanced as a result of climate change” (Kos et al 2016).
In 2007, a long term study was initiated on the paraglacial response of the Moosfluh rock slope instability located at the terminus of the Great Aletsch glacier in Canton Wallis, Switzerland.
The glacier has been undergoing rapid retreat and volume decrease, and as a consequence, a number of rock slope instabilities around the glacier’s terminus are responding directly those rapid changes (see MSF and DSF in the accompanying landslide distribution map).
For the first time, we quantified the spatial and temporal relationship between the lowering of glacier ice and the acceleration of a landslide response, which was previously thought to occur over much longer time frames.
The data acquired for this study was one of the first times that satellite, airbourne, and ground-based remote sensing was combined with in situ monitoring data and field mapping to provide an unprecedented insight into paraglacial slope processes.
The publication is available on the Geophysical Research Letters website, via this external link.
Key outcomes of the study:
A timely early warning…
Based on time series displacement maps from the period 2012 to 2017, we identified that the rock slope underwent a transition from a sub-critical to critical stability state. Several weeks prior to the catastrophic failure, an early warning was issued to Cantonal authorities.
Following the rock avalanche event of August 23, Terrasense was contracted by the Canton Graubünden (AfWN), in collaboration with Bonanomi Ltd to measure and support interpretation of the stability state of the rock slope. Our inputs played a central role in decision-making during the post-crisis intervention by local authorities.