The Brienz slide in the Graubünden municipality of Albula/Alvra is closely monitored by numerous systems. The Early Warning Service team assesses the collected data and images and continuously prepares an analysis from them. This helps to identify any risks to the settlement area at an early stage and to warn the municipality. Geologist Stefan Schneider heads the early warning service.
What are the tasks of the early warning service?
We monitor the landslide with various systems and evaluate the measurement data. From this, we can identify geological developments and assess the risk situation. As a consulting expert, I then contribute these findings to the community's management staff.
Who works in the early warning service?
The core team consists of four geologists who share the tasks related to the early warning service. This allows us to ensure that the Brienz slide is monitored around the clock, every day of the week. We are also advised and supported by the overall project manager from the Office for Forests and Natural Hazards and the two geologists from the canton.
Which monitoring technology is used?
We operate nine measurement stations with very precise GPS receivers, which provide an exact position every day. From the measurement house in Brienz/Brinzauls, over 30 points on the mountain are measured fully automatically every two hours. And since last summer, a georadar has also been in use, which provides us with millimeter-accurate data, especially when evaluating the “island” scenario.
Why are there different techniques?
The three measurement systems complement each other; each system has its advantages and disadvantages. For example, the measurement points cannot be measured from the village in bad weather and fog. In such situations, we can then access the georadar and GPS data. It can also happen that a system fails due to technical problems. It is therefore important that we have various, independent systems and that redundancy is guaranteed.
How often do you look at the measurement data?
The data is checked daily and interpreted by geologists. However, in the event of extraordinary events, we may also view and interpret the data several times a day.
How would you know if the situation were to get worse?
For us, the changes in the movements of rock masses are particularly important. If landslide velocities on the mountain were to suddenly increase excessively quickly and over a large area, this could be critical.
When would you start sounding the alarm?
We observe the movement patterns very closely and also monitor them using mathematical models. These show us when things can become critical. When an extraordinary development emerges, we first discuss the situation internally with geologists from the Early Warning Service and experts from the canton. If we come to the conclusion that the situation has changed significantly, we will inform the Chief of Staff and the community leadership staff. Depending on the situation, the community leadership team then meets and decides on further measures, including evacuation.
When do you have to evacuate the inhabited area?
The safety of residents is paramount. If a rock slide were on the horizon, we would evacuate.
How quickly could that happen?
Large rock breaks, which could endanger the village and its inhabitants, do not occur spontaneously, but are announced hours to days in advance and can be identified by the early warning service. This would leave time for an orderly evacuation. The community is prepared for this.
The mountain has been moving for many generations — the people of Brienz know that. Why the comprehensive measures taken in recent months?
The rate of the village landslide has increased almost twenty times since 2000. For many years, the movement was five or six centimeters per year and today we are almost one meter twenty. Houses, roads and lines are suffering severely from this movement. In addition, there is a certain risk of a rock slide from above. This significant worsening of the situation in recent years has made various measures necessary.
Does the early warning service give us total security?
There is never total safety in nature. But our cutting-edge systems and experienced specialists give the village and its residents the security they need to live.
They have a huge responsibility. Do you sleep well at night?
(smiles) The responsibility is indeed great. However, we are an experienced team and share responsibility over several shoulders. It is our job to assess natural hazards. So I'm sleeping well, thanks!
About the person
“Rocks are like books: If you understand their language, they tell you a lot of stories,” says geologist Stefan Schneider (46), who has been working intensively on Brienz slip since 2011. He grew up in Affoltern am Albis and studied Earth Sciences at ETH Zurich. After five years in Valais, he joined CSD INGENIEURE AG in Thusis in 2005. Today, he heads the branch there with 13 geologists and environmental experts.
Originally ended up in the mountains for professional reasons, Stefan Schneider has also set down roots privately in the canton of Grisons over 15 years. He lives in Scharans with his wife and three children. He is fascinated by the various dimensions that come together in geology. “We look back millions of years to understand the Earth and learn from it for the future,” he says. “Viewed under a microscope, the smallest rock samples can reveal large relationships in a mountain or the entire planet.”
This interview was published in the monthly bulletin (February 2020) of the municipality of Albula/Alvra on Brienz Rutsch. It informs those affected and the public on a monthly basis about the current development of the slide and the findings about it and can be used by the municipality (www.albula-alvra.ch) can be downloaded. The bulletin is designed and implemented by Christian Gartmann.