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Slopes in motion: rockfalls and landslides

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When soil and rock break off from steep slopes, people and buildings in the valley below are placed in great danger. We research rockfalls, hillslope debris flows und landslides so that risks can be assessed and damage prevented. Through our research, we not only get stones rolling - but even boulders.


In a mountainous country like Switzerland, not everything that comes from above is good: 6 to 8% of Switzerland's surface area is unstable ground – mainly in the pre-alpine and alpine regions. In 2012 alone, rockfalls and rock slope failures claimed the lives of five people in Switzerland. Hillslope debris flows and landslides occur suddenly, can be predicted only to a limited extent and often move at high speeds, which makes them a serious threat to valley inhabitants. Given that they unleash such colossal forces, protective structures and safety measures often face technical difficulties or are simply too expensive.

Hillslope debris flows are formed when soil on hillsides becomes waterlogged during heavy rain and effectively liquefies. This debris pose a serious threat to buildings, roads and railway lines. In shallow landslides, the top layer of earth moves and slides down; these landslides contain less water than hillslope debris flows.

Climate change could exacerbate these risks further: melting glaciers and thawing permafrost release rocks and boulders from their icy grip. If heavy rainfall increases as predicted, hillslope debris flows and shallow landslides could also occur more frequently.

Rolling stones

We examine the processes of these natural hazards in order to improve hazard mapping, early warning and protective measures. We measure rockfall by rolling rocks mounted with measuring probes down mountain slopes. This allows us to gather information about their route, rotation and impact. This data is then fed into the rockfall module of our natural hazard simulation software RAMMS.

Dangerous mud

During storms involving many shallow landslides, we study severely affected regions so that hazard maps can be improved. We submit the data to researchers and civil protection authorities via our hillslope debris flow database. We gather experimental data both in the field and in our large-scale laboratory: We simulate hillslope debris flows on a ramp in the laboratory and examine how vegetation affects the stability of earth layers using apparatus which we ourselves have developed. The data is also fed into the RAMMS module in order to simulate debris flows.




We research rockfall processes in order to evaluate the risk of falling rocks more accurately and to improve protection against rockfalls.

Hillslope debris flows

Rainfall can cause soil to become waterlogged, which can in turn lead to hillslope debris flows. We observe and research this process.

Research in pictures

Have a glance at the destructions caused by natural hazards, but also at our research. Click here for the image gallery.


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