95% of global communications pass through fiber optic submarine cables. They travel the oceans and run along our coasts. A network that spans the entire planet and may well find a new application unrelated to the Internet. French researchers have indeed proven that it was possible to use them to detect earthquakes.
In an article published in the journal Nature Communications, scientists from the CNRS, the Observatoire de la Côte d'Azur, the Research Institute for Development and the University of the Côte d'Azur detailed how they had used a 41 km cable off Toulon to identify a microseism of magnitude of only 1.9 located a hundred kilometers away. The accuracy was close to that of a seismic station.
Optical fiber is also sensitive to swell
Another international study published the same week in Nature Communications and conducted by the California Institute Technology used fiber optic cables from the North Sea to locate an earthquake … in the Fiji Islands, a magnitude of 8.2.
The optical fiber contains small impurities which return part of the light transported towards the transmitter. During the passage of a seismic wave, the impurities are modified. It is therefore possible to use submarine cables as sensors. All you need to do is inject light pulses into the fiber and analyze the returned signal.
Other perspectives are opening up, such as capturing the noise pollution produced by ships or cetaceans. But above all, French scientists have managed to record the swell footprint to which optical fiber is also sensitive. They therefore hope to learn more about the vibrations that constantly stir the depths of the oceans and the interior of the Earth.