Scientists from ETH Zurich have deliberately triggered thousands of tiny earthquakes deep beneath the Swiss Alps in a controversial experiment designed to better understand seismic activity and its potential control.
Experiment Details
The Fault Activation and Earthquake Rupture (FEAR-2) experiment, conducted by the BedrettoLab at the end of last month, involved injecting 750,000 litres of water into two boreholes over 50 hours. Despite an unexpected power outage, the team successfully induced a total of 8,000 minor seismic events.
To reach the target fault zone, researchers first constructed a 120-metre-long tunnel starting 2.2 kilometres from the main Bedretto tunnel entrance. A dense monitoring network of sensors was then installed on and around the fault to track temperature, seismic activity, and other parameters.
Safety Measures
All high-pressure injection activities were controlled remotely from Zurich, ensuring no personnel were present in the tunnel during stimulations. The experiment passed rigorous safety and risk assessments, with multiple layers of safety protocols in place. The induced seismicity remained well below damaging levels, with peak ground acceleration values approximately 7,000 times lower than those associated with damaging earthquakes.
Scientific Goals
The project aims to understand natural earthquake triggers and develop methods to prevent them. Professor Domenico Giardini, a lead researcher, stated: "If we master how to produce quakes of a certain size, then we know how not to produce them." The findings could also facilitate large-scale use of deep geothermal energy, a nearly inexhaustible resource with a small ecological footprint.
Results and Implications
While many seismic events occurred on the target fault zone, a significant number took place on neighbouring geological structures activated by the fluid injection. The experiment was halted when events began occurring outside the core measurement network, limiting scientific analysis. However, researchers consider the study a success, demonstrating that controlled earthquakes can be carried out safely.
The Earth's tectonic plates move through the mantle, producing earthquakes as they interact. This research offers a unique opportunity to observe fault behaviour up close, contributing to better earthquake prediction and hazard mitigation.
