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The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.
Back in the summer of 2023, Brienz in Switzerland was evacuated due to the threat of a large rockslope failure that threatened to bury the village. The so-called Brienz-Brinzauls landslide finally failed on 15 June 2023, with the debris from the 1.2 million cubic metre landslide stopping just short of the community. I subsequently featured a paper that highlighted the role of monitoring in the management of the risk.
Unfortunately, the slope above Brienz has once again started to move rapidly, and the residents are preparing to evacuate once again. Frankfurter Rundschau has a very nice article (in German) about the situation, which highlights the high level of frustration felt in the community that they are being displaced once again.
There is a Youtube video that shows a briefing, also in German, about the situation. This includes this graph that shows the movement of the slope over recent years:-
The movement rates are quite high, and the recent acceleration is very clear. A graph showing the more recent acceleration was also provided, which shows the recent increases, plus the timing of large rainfall events. It is clear that the slope is responding to high precipitation inputs.:-
Note that the most recent data suggests a slowing trend, responding to less rainfall.
The image below shows the area of the slope that has been moving rapidly:-
It is estimated that over 1 million cubic metres of broken rock is moving at rates of up to 30 cm per day. Forecasting likely future behaviour in a mass like this is very challenging, and hence the evacuation.
The news reports indicate that a catastrophic failure is not considered to be the most likely scenario, but it cannot be ruled out either. It is deeply unfortunate that our understanding of the dynamics of these types of slope is insufficient for us to be able to predict confidently the likely outcome of this movement event. One can only feel sympathy for both the residents of Brienz (mainly), whose lives are being disrupted once again, but also for the scientists and officials managing the situation, who will be feeling the full glare of public interest.
Text © 2023. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.
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