Scientists Trigger Controlled Quakes Beneath the Alps to Hunt for Early Warning Signals

Scientists trigger controlled earthquakes beneath the Alps to hunt for early warning signals

Researchers with the Fault Activation and Earthquake Rupture (FEAR) project are deliberately inducing small earthquakes from a tunnel deep under the Alps. The work — carried out from an old railway tunnel on the Switzerland–Italy border — is not meant to cause harm. Instead, the controlled experiments aim to identify measurable physical precursors that could reveal how and when larger ruptures begin.

Despite expanding seismic networks worldwide, scientists still lack a clear understanding of the immediate triggers that set ruptures in motion, or why some breaks stay short while others propagate for miles. Domenico Giardini, professor of seismology and geodynamics at ETH Zürich, told Live Science that most useful signals only become obvious after a quake. The FEAR experiments are designed to observe those signals before and during rupture.

How the experiment works

The Alps carry enormous compressive stress from tectonic forces, producing faults at depths of roughly 0.6 to 1.2 miles (1 to 2 kilometers). Using an existing tunnel that provides close access to one such fault, the FEAR team pumps water into the fault to raise pore pressure and lower friction, stimulating slip on a controllable schedule.

This mechanism is similar to seismicity linked to wastewater injection in regions such as Oklahoma and Texas: added fluid lubricates faults and can encourage slip. The key difference in the FEAR experiment is the dense instrumentation array — hundreds or thousands of seismometers and accelerometers deployed directly on and around the fault — which lets researchers record tiny, rapid changes in fault behavior with high precision.

What they've observed and next steps

So far the team has induced hundreds of thousands of very small events up to magnitude 0 (the magnitude scale is logarithmic, so microquakes can register at zero or even negative values). In the coming week the researchers planned to inject hot water to study temperature effects on rupture evolution, and in March they intend to escalate controlled injections to produce events up to magnitude 1.

"What are the signs that nature is telling us? Invariably, they become clear after the quake, not before, so we are trying to understand much better how to see the signs," — Domenico Giardini, ETH Zürich.

The broader goal is to link measurable conditions — such as local strain, pore pressure, temperature and the mechanical state of the surrounding rock — to the size and propagation behavior of ruptures. If these links can be established in controlled settings, they could be applied to hazardous faults elsewhere to better estimate how close a fault is to producing a damaging earthquake.

Implications and caution

FEAR's experiments offer a rare opportunity to watch rupture nucleation and early growth in detail. Early results suggest factors like strain in rock neighboring the fault influence how ruptures start and whether they jump to adjacent faults. While promising, translating controlled, small-scale results into predictive tools for large, natural earthquakes remains challenging and will require continued observation, modeling and cross-validation with natural events.

Safety and oversight: The project uses small, well-monitored injections and operates under scientific and regulatory oversight. The induced events are tiny compared with damaging natural earthquakes, and the project's intention is to improve society's ability to assess and mitigate seismic risk.

Source: FEAR project reporting and statements by Domenico Giardini (ETH Zürich).