In 2019, the Bedretto tunnel was identified as an ideal place to establish a deep underground laboratory. Shortly after, an agreement with the tunnel owner, the Matterhorn-Gotthard-Bahn, was signed and the preparatory work begun. The tunnel needed to be secured and the infrastructure was installed in the main cavern 2 km deep into the tunnel, to enable conducting outstanding scientific experiments. To gain a better understating of the rock properties, a geological characterization phase took place. At the same time, we tested equipment and the instruments, many of them newly developed for our specific purposes. Finally, a first experimental testbed has been set up, by drilling ten 250 to 400 m long boreholes below the main cavern and equipping them with hundreds of sensors, effectively transforming a large volume of rock in a unique sensing testbed.
Following this extensive preparatory work, the BedrettoLab is now ready for the next phase, where we really want to get to the bottom of things. The three experimental projects FEAR (Fault Activation and Earthquake Rupture, an EU ERC Synergy Project), MISS (Mitigating Induced Seismicity for Successful Geo-Resources Applications, financed by the Werner Siemens Foundation), and VALTER (VALidating of TEchnologies for Reservoir Engineering, financed by the Swiss Federal Office of Energy) are of particular importance for this phase.
Whereas VALTER focuses on different aspects of building and operating a geothermal reservoir in a safe and efficient way, MISS and FEAR are interested in fundamental earthquake processes – how earthquakes start and stop, how faults slip – and use for this purpose the tiny earthquakes induced by water injections as well as fault stimulations. The installation of a second testbed to host the FEAR and MISS experiments is now starting. For this purpose, the BedrettoLab will be extended by retrofitting additional caverns deeper in the tunnel to double the rock volumes available for experiments. Further, an additional side-tunnel of about 100 m length is planned, making it possible to monitor the target fault at close distance and add new monitoring boreholes equipped with hundreds of sensors. Outside the tunnel, this work will not be noticeable. However, the excavated material is high-quality Granite and will thus be transported from the site for further. Theses extensions are planned to be completed by summer 2022. 14 October 2021