“We begin to understand how faults move under the Alps”

Where did the idea of creating a rock laboratory come from?

In the past, the unwanted consequences such as felt or damaging earthquakes at large scale geothermal projects showed that we need to understand better what happens deep underground if we inject water or extract hot or cold water. The difficulty is, that geothermal reservoirs with temperatures of at least 180°, required for the generation of electricity, are necessarily 4-6 kilometres deep underground in non-volcanic regions like Switzerland. Normally we only know little about the deep underground and are forced to conduct most measurements from the surface. So, we knew, if we want to exploit geothermal energy in the future in Switzerland, we need to have a better understanding of the processes in the deep underground. There are already two underground laboratories in Switzerland (MontTerri and Grimsel). The experiments that we conducted for two years in Grimsel allowed us to work at a depth of a few hundred meters and a scale of a few tenths of meters. But we were looking for larger rock volumes and depths of 1-2km, and consequently we needed to find a suitable place with appropriate conditions.

How did the selection process for the BedrettoLab work?

There are a number of existing tunnels in Switzerland that were well known to the geological community. When we wanted to start this new underground lab, we consulted with our geologists to choose a suitable tunnel. In the end, we had a selection of three possible tunnels and chose the Bedretto tunnel for several reasons: First of all, the geology per se was a key criterion. The granite that we have here is representative for the basement geology in Switzerland and the fact that the tunnel is not cemented over a length of over 5 kilometers is incredibly helpful for our experiments. We can “read” the history of the tunnel from the tunnel walls and most of all we can see the faults. A second favourable aspect of the Bedretto tunnel are logistics, which also include safety aspects. The two exits, one in direction of the Bedretto valley and the other to the Furka tunnel, guarantee the accessibility in an emergency. Also, you can reach the tunnel easily with public transport or by car. Those are the most important scientific and practical advantages. And in the end, having the Matterhorn Gotthard railway company (MGB) as an owner, who is managing the infrastructure and has an interest in maintaining the tunnel turned out to be extremely helpful. They became a valuable partner as the MGB is always very constructive in supporting.

What has been your personal highlight since the BedrettoLab has been established?

Overall, I am overwhelmed by the enthusiasm that people bring to this project! It’s not a given that people spend days and nights working in a tunnel deep under the Alps. And we are talking about a large group of people: now our team consists of around 40 people. The work in the tunnel has of course an adventurous component. And a big incentive is that they are working at the frontier of knowledge. Everything that we now have installed didn’t come off the shelf, but we needed to develop customised solutions. This is certainly motivating. I can see it every day that the whole team is giving the maximum. And for me, this enthusiasm is the most rewarding aspect in this whole operation.

And what was the biggest challenge?

The operation is larger than we had foreseen. The contractual part turned out to be very challenging, with many contracts, projects and orders. The larger orders have to be approved by the ETH legal team to comply with applicable regulations, and in the end by the Board of ETH. In general, this means that the whole administrative process gets more comprehensive and complicated. Work underground is really expensive and we need to secure the funding for all our operations as well as for running a functional and safe underground laboratory. It is sometimes difficult to make the value of certain interventions visible; for example, a 400-meter-long borehole full of cemented sensors does not look like much from the tunnel wall, but it’s a very sophisticated and expensive research facility. After all, the administration is confronted with new topics and so are we. Finally, to have an extra level of internal monitoring and supervision, we have an Oversight Committee consisting of persons from the administration and from research. And they advise us with larger strategic decisions. Overall, operating an underground lab of this scale is very interesting in terms of the science that we can do here, but is challenging.

What are the main findings with regards to the mitigation of induced earthquakes in the context of operations targeting the deep underground?

We have many firsts. For example, we demonstrated for the first time that you can install and engineer a reservoir in different stages, and we could demonstrate that you can steer, monitor and model separately each stage. With this new method you minimize the seismicity and control where the water goes. This had never been done before. At first, we explored this within the DESTRESS project and then later we tested and developed it further in the VALTER project. For Geo Energie Suisse (GES) it was a key to get permission to go ahead with the geothermal project in Haute-Sorne. Now we have gained lots of new data and scientific knowledge from that. And in parallel we learned many things about the geology and the fault system. Further, we gained insights about the behaviour of the whole mountain. This is totally new because we started to install instruments that measure seismic activities where they happen. We are beginning to understand how a mountain moves underneath with the data that we are collecting. We tend to think of a mountain as a pile of dead rock. This is not the case! It’s a living object.

The construction work for a new side tunnel will begin in early summer this year. This side tunnel is part of the earthquake research project called “FEAR”. Can you describe the purpose of this tunnel?

FEAR is the largest funding released to date in Earth Sciences by the ERC Synergy Grant program of the European Union, with the aim of studying the physics of fault activation and earthquake initiation. Following extensive investigations, we now know about the fault systems that we have in the tunnel and we know which ones are active. We identified a system of faults that intersect each other. And in order to be close to them we need a side tunnel that follows one fault on which we will induce a small earthquake and investigate intensively how the fault behaves before, during and after the quake. With a series of boreholes, we can monitor the fault and inject water from nearby. This wouldn’t be possible to do from the main tunnel.

To which questions would you like to find answers within the next five years? Is there a vision that you have for the BedrettoLab?

I’m a researcher at heart but I always try to get products or answers coming out of my research that serve our society – consequently I remain loyal to both parts. I am still fully convinced that if we have a better understanding of how a quake starts and stops and when an active fault is becoming critical, it would be a huge benefit for many sectors of society in terms of seismic risk mitigation. What signal is an active fault giving us? When is a quake about to start? When and why does it stop? These are all questions to which we want to find answers in the BedrettoLab. You're dealing with an object that can be a hundred kilometres long, if not a thousand kilometres long and the preparation phase can last centuries and, in the end, everything happens in a second. A better understanding of all these processes would be fundamental, as we have seen in the tragic Turkey-Syria earthquake sequence that happened in February. This and the research on the extraction and storage of geothermal energy remain the key disciplines of the BedrettoLab. But of course, we have researchers of other disciplines using the tunnel for their domain, for example the geobiologists now looking for forms of life surviving in the rock kilometres below the surface. After all, I will retire in a few years and I am happy to know that younger colleagues with new ideas continue research in the BedrettoLab.