News

Injection operations began on 21 September at the BedrettoLab Earthquake Physics Testbed. Water was injected into two boreholes using a set of pumps. In contrast to the experiment conducted in April, the team tested a different operational approach by applying high injection flow rates from the start. 

At 6:30 a.m. on 23 September, a seismic event with a local magnitude of 0.6 was triggered. Following this event, and after a total of approximately 590 m³ of water had been injected and almost 7000 events with magnitude down to –4.7 were recorded, the team decided to conclude the experiment and stop the injection. The boreholes will remain closed while microseismic activity continues to be monitored over the coming days. 

The experiment once again demonstrated that faults can be activated within the BedrettoLab Earthquake Physics Testbed and that the resulting seismicity remains within the expected range. In FEAR 3, the maximum magnitude produced in the BedrettoLab to date increased by one order of magnitude, as planned. 

Ground shaking measured outside the tunnel remained extremely low. Peak ground acceleration values recorded at the tunnel entrance, the Furka Base Tunnel and the Capanna Piansecco entrance ranged from 0.03 to 0.27 milli-g. These values are approximately 2,000 to 3,000 times below the design ground acceleration specified by Swiss standards, around 150 times below the threshold at which shaking can typically be felt, and approximately 1,500 times below levels associated with damaging earthquakes. 

The team will now analyse the data and prepare for the next round of experiments. This will be preceded by a drilling campaign to place sensors close to the seismogenic areas identified during this FEAR 3 experiment.