A tunnel on the fault to study earthquakes up close

A 120-meter- long tunnel running alongside a fault allows for close-up study of earthquakes and answers to two of the most important and unresolved questions in seismology : what happens just before an earthquake starts and what causes it to stop . It has now been built in the Ticino Alps of Switzerland , at the BedrettoLab of the Swiss Federal Institute of Technology in Zurich, to conduct experiments under the FEAR project , in which the National Institute of Geophysics and Volcanology in Rome is also participating. The project was funded by the European Research Council with 14 million euros.

"The fault observatory is the missing piece in the earthquake study puzzle," comments Domenico Giardini of the ETH and former president of the INGV, one of the project coordinators. "We have excellent monitoring networks around the world, but most of them are located on the surface, and therefore many kilometers away from the earthquakes' origin. Furthermore," Giardini continues, "even the few sensors in the wells are normally located only near the fault zones, not inside them ."

Thanks to the tunnel's proximity to the selected fault, researchers will be able to study in detail how an earthquake forms and propagates until its energy is exhausted. They will also be looking for precursor signals that could help predict stronger earthquakes in the future. The wells dug to reach the fault are equipped with a wide range of sensors , forming a unique monitoring network . Some of the wells will also allow water to be injected to trigger small earthquakes of magnitude 1 , a value well below the threshold of human perception but still capable of producing strong ground movements.