New method uses existing fiber optic lines to detect, localize and classify environmental events

By changes in the wavelength of light pulses in fiber optic cables, researchers at TU Graz can measure where rockfalls, landslides, fires and earthquakes are taking place. Landslides and rockfalls are increasingly becoming a real threat to people and infrastructure in light of the changing climate and the associated changes in soil and rock structure. The more precise the measurement, the earlier hazards can be detected, and consequently damage can be limited or even avoided altogether…. can also detect signs of fatigue in infrastructures, fires, leaks or earthquakes—all of this can be observed along the entire fiber, not just at individual measuring points. This complete coverage lacking in blind spots represents a unique advantage over conventional measuring methods….already being used….

“We send light at a certain wavelength into the fiber and analyze the reflected spectrum. When the light pulse returns, it normally has the same wavelength as before. When something happens in between, however, non-linear effects occur, which appear as slightly offset wavelengths or intensity variations. Depending on the measurement method, I can use these changes and the runtime of the signal to determine at which point of the measured fiber a vibration, temperature change or strain change has occurred. As we have shown in both laboratory and field measurements, the sensitivity of our measurements is in the nanometer range, which means that even the smallest changes can be detected,” explains Werner Lienhart, head of the Institute of Engineering Geodesy and Measurement Systems at TU Graz.
New method uses existing fiber optic lines to detect, localize and classify environmental events
Phys org July 13, 2023
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