Earthquakes are one of the most significant hazards for human society, and, at the same time, remain the most elusive. Improving the ability to forecast earthquakes is one of the main challenges remaining for the natural sciences. With the European Research Council (ERC) Synergy project “Fault Activation and Earthquake Rupture” (FEAR), a consortium of scientists from the Eidgenössiche Technische Hochschule Zürich (ETH Zurich) in Switzerland, the Rheinisch-Westfälische Hochschule (RWTH Aachen University) in Germany, and the Instituto Nazionale di Geofisica e Vulcanologia (INGV) in Italy are conducting a suite of ambitious experiments in the world-unique Bedretto Underground Laboratory for Geosciences and Geoenergy (BedrettoLab), an underground experimental facility in the Bedretto Tunnel, located at 1000m depth under the Swiss Alps. The core idea of FEAR is to gain understanding on how earthquakes start and stop by using hydraulic stimulation to modify stress and initiate small non-damaging earthquakes (magnitude ~1.0 events on fault patches of 10-50m scale) on candidate faults in the vicinity of the Bedretto Tunnel. A dense network of multidisciplinary sensors will capture the rupture preparation phase, the earthquake rupture, and the post-rupture response of the rock mass. These experiments will give unprecedented up-close near-field insight into the physics of earthquake processes, contribute to pushing forward the current limits on earthquake predictability and advance the state-of-the-art in safe use of geoenergy.
The drilling campaign for the Bedretto On-Fault Observatory (BOFO) has started last week. The BOFO observatory is going to be part of the monitoring system of the FEAR project allowing us to closely observe any seismic activities in and around the fault zone, which is the study object of the FEAR project. The BOFO forms the first part of the FEAR integrated monitoring system that will ultimately be completed when the new side tunnel is finished and further boreholes can be drilled.
In the next two weeks, eight boreholes will be drilled with a length of 8 to 12 meter each. They are designed to place highly sensitive acoustic emission sensors in the shape of four tetrahedral arrays.
The FEAR Annual Meeting took place in Airolo and Bedretto this week. The team of almost 50 participants from ETH Zürich, RWTH Aachen, and INGV Rome gathered to share their results and discuss the next steps of the project.
The meeting focused on preparing for FEAR the experiment 1. A lot of things need to be done to get there. Boreholes have to be drilled, prospection campaigns carried out, a tunnel designed and constructed, monitoring systems designed and optimized, rock samples have to be tested in the lab, numerical models calibrated, parameter values and their uncertainties estimated, a real-time traffic-light risk mitigation system and remote control for safe operation of the experiment implemented.
The last few days were spent with lively discussions and in-depth breakout sessions on who will do what and when, so that one year from now, we can push the button. After all the hard work, some fun and games were in order. There was a visit to the BedrettoLab with dinner and a concert.