This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: In recent years, the Alps have experienced devastating glacier collapses: In September 2023, a section of the Marmolada glacier in the Dolomites collapsed, resulting in the deaths of seven mountaineers. Just over a year and a half later, in May 2025, the Birch Glacier above Blatten collapsed, keeping Switzerland and the entire world in suspense.
Crevasses are crucial to the stability of glaciers, not only those that satellites and drones can detect on the surface but also those hidden within the ice. This is because meltwater can deepen them and accelerate the collapse of glaciers and ice sheets. Researchers use seismic techniques to explore the inner workings of glaciers.
Microearthquakes occur when crevasses open within the ice, and seismometers can detect them to pinpoint their sources. However, these measurements lack high spatial resolution, and deploying many seismometers is challenging because of high costs and the difficulty of installing them on a glacier ridden with crevasses. ETH researchers led by Assistant Professor Thomas Hudson from the Environmental and Exploration Geophysics Group have demonstrated in a new study published in Science Advances that this can be done more simply, cost-effectively and with significantly higher spatial resolution.
For testing, the researchers laid a single fiber-optic cable on the surface of the Gorner Glacier in Valais. This enabled them to explore the glacier's internal structure to a depth of 25 meters (82 feet). "A single fiber-optic cable replaces hundreds of seismometers," Hudson emphasizes.
The cable simply needs to be connected to what is known as an interrogator, which injects a light signal into the fiber and records the scattered light signals reflected back. Seismic waves are generated when a microearthquake occurs, such as when a crevasse opens in the ice. These waves cause slight local deformation as they hit the fiber, leading to changes in how the injected light is deflected and reflected.
This results in a change in the baseline signal, alerting researchers to the location and depth of a crevasse. Using computational methods, the researchers can determine the structure of the ice and gain insight into its internal composition, similar to an ultrasound scan performed by a doctor. Analyzing the data is computationally demanding because of the vast amount of data generated.
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