News from the BedrettoLab – earthquakes explicitly welcome
- Petra Fritz
- 2 days ago
- 5 min read
The BedrettoLab (Bedretto Underground Laboratory for Geosciences and Geoenergies) is a unique research facility of ETH Zurich that provides a precise view into the Earth’s interior. For this reason, it is also referred to as the Bedretto Window. It is located in the Swiss Alps, approximately 1.5 kilometres deep inside the mountain, within a 5.2-kilometre tunnel in Ticino. In this unusual rock laboratory, researchers have for several years equipped fault zones with numerous sensors to better understand how earthquakes originate. Knowledge of this kind could, in critical situations, save many lives.
Even in extremely low-seismic countries such as Switzerland, noticeable tremors still occur from time to time. Most recently, in mid-2025 near Mürren (Canton Bern), a magnitude 4.2 earthquake was recorded. While it did not cause significant damage, it did trigger a rockfall in the nearby Sefinental which – unlike the massive rockslide in Blatten/Valais in May – fortunately remained without consequences.
Equipped with state-of-the-art technology, the BedrettoLab offers ideal conditions for experimental research with a focus on “behaviour of the deep subsurface during development and stimulation”. Such access provides a perfect field for advancing scientific insights in geothermal energy and earthquake physics.
Two hours deep inside the mountain with experienced scientists
This tunnel section, the Ronco gallery in the Bedretto Valley extending to the Furka Base Tunnel, is considered the longest unused tunnel in Switzerland. Until 2004, the Bedretto tunnel was still inspected regularly; three collapses after 2004 in the northern section eventually made it inaccessible. When, in 2015, a ventilation system was installed in the middle of the tunnel to supply fresh air for nearby construction work on the Furka Base Tunnel, the Bedretto tunnel was also made accessible once again. Since 2019, the southern portion has found a new purpose as a rock laboratory. Once a year, interested visitors are given the opportunity to explore this remarkable research station. The highly informative ETH website also offers a virtual insight into the working environment.
The tunnel ends or begins at the edge of a gravel pit, where the course of the dismantled railway tracks can still be seen today. A water channel runs on the right-hand side, and in many places water drips from the ceiling and the walls. The temperature remains between 9 and 12 degrees Celsius throughout the year. Waterproof clothing and sturdy footwear are essential for the visit.
Accompanied by three scientists, visitors equipped with helmets and headlamps make their way ever deeper into the mountain. At several points, explanations are given about larger or smaller fissures in the rock formations (mostly gneiss and granite). Drill cores lie on the ground, countless pipes and cables run along the walls, measuring instruments and flickering monitors appear at regular intervals. After about 40 minutes on foot, the “epicentre” of activity is reached. Although no work or experiments are taking place on that particular day, the various pieces of equipment such as drills and sensors are present and accessible. Several information boards explain the research methods and techniques. The scenery and set-up are unmistakably reminiscent of various fracking procedures.
Focus on earthquake and geothermal research
A monitor displays, among other things, the smallest tremors per second, showing continuous zigzag lines running in parallel. The spontaneous idea arises to jump or stomp vigorously in front of the device, but it produces no visible change in the pattern. This means that natural micro-earthquakes and ground movements lie well above this threshold of vibration, although a human cannot feel them.
Artificial earthquakes triggered here reach a maximum magnitude of 1. This level is also well below the threshold of human perception, which according to ETH Zurich is around magnitude 2.5 at the surface. For such tests – under the project name FEAR – a new 120-metre-long side tunnel has been cut into the mountain. It runs parallel to a natural fault zone, allowing optimal research conditions. Water is injected into the fault at high pressure to move small rock blocks – more precisely, to shift a 50-metre rock block by about one millimetre.
Two German participants in the visitor group are also specialists, currently working on the expansion of the Gotthard road tunnel. They exchange professional thoughts, inviting me into their discussion: what level of pressure would be required to trigger a quake 1.5 kilometres deep using this fracking-like method? We calculate well over one thousand bar. Explosions are extremely rare, and no personnel remain in the tunnel during any test triggering. Only the equipment stays behind, transmitting data around the clock directly to Zurich for evaluation.
In principle, researchers assume that pressure waves initiated in this controlled manner will diminish with distance from the epicentre, much like ocean waves. However, due to the geological structures – for example, unknown cavities – one can never be entirely certain whether amplifications or stagnations might occur elsewhere. This could potentially increase energy release and trigger larger shifts or tremors. If such events do occur, they would in any case manifest naturally sooner or later. For this reason, researchers find public scepticism difficult to fully comprehend. The process is somewhat comparable to the preventative artificial triggering of snow slabs to avoid uncontrolled avalanches – here, to avoid the build-up of tectonic stress and potentially prevent stronger earthquakes.
“We are beginning to understand how fault zones beneath the Alps move”, said Prof Domenico Giardini in an initial report from April 2023. “Particularly in large geothermal projects, it is essential to know what happens deep underground when we inject or extract water.” The difficulty lies in the fact that geothermal reservoirs reaching at least 180°C (as required for electricity generation) are necessarily located four to six kilometres below the surface in non-volcanic regions such as Switzerland. In Central Europe, temperatures increase by an average of 3°C per 100 metres of depth. Therefore, knowledge of the deep subsurface remains limited, and most measurements must be conducted from the surface. Until now, Switzerland had only two subsurface laboratories – Monte Terri and Grimsel – which operate only a few hundred metres deep and on a scale of several decimetres.
The latest findings from BedrettoLab can be followed online. Interactive, interdisciplinary science can hardly be more fascinating, practical, or forward-looking.
Newest interdisciplinary approach – microbial research
Research at the BedrettoLab now goes beyond earthquakes and geothermal studies. Under the project name DELOS (Deep Life Observatory), geobiologist Cara Magnabosco searches for microorganisms living deep within the rocks of the BedrettoLab. These findings may provide new insights into how life originated. “It is estimated that more microorganisms live deep underground than on the Earth’s surface and in all bodies of water combined,” says Magnabosco. Unlike almost all accessible tunnels or vertical mine shafts, the walls of the Bedretto tunnel have never been lined with cement or concrete. This makes it possible to take samples of rock-dwelling organisms from many different points. Most measuring stations collect water that seeps through natural fractures or fissures. Researchers analyse these water samples, isolate the organisms, and extract their genetic material.
Recent studies show that the biodiversity within the BedrettoLab is enormous. Researchers have identified no fewer than 14,500 sequencing variants, used as a measure of microbial diversity. This richness – 64 different biological strains – surprised even them, says Magnabosco. Interestingly, the composition of microbial communities varies significantly from one location to another. Particularly spectacular was the discovery of a population of ultra-small bacteria. They are roughly ten times smaller than “normal” bacteria, reaching lengths of only around 200 nanometres – a billionth of a metre. Magnabosco finds it even more remarkable that even the smallest tremor caused short-term changes to the bacterial populations at one measuring point.
In the long term, such research could represent an important step towards understanding the conditions necessary for the emergence of life on distant worlds.
Article and photos by Petra Fritz
