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The cables that bring you high-speed internet could provide a cheaper and more efficient alternative to the traditional ways of listening out for earthquakes.
Optical fibre cables transmit information using light travelling through glass fibres. Light loses less energy and move faster than electrons moving through electrical cables, making fibre-optic cables more efficient – which is why they are the favourite for telecommunications like high-speed broadband.
Now, the cables already underground around the world could come in handy for another reason. They may provide a low-cost way to detect earthquakes.
When an earthquake happens, it sends a series of seismic waves through the ground in the form of vibrations. First, there are waves which send vibrations in the same direction it travels, the so-called P waves. These are followed by S waves, which send vibrations at 90 degrees to the way they travel. Both carry information about the size and location of the centre of the earthquake.
Researchers at the German Research Centre for Geosciences have published a new paper, in Nature Communications, that shows fibre-optic cables can be used to measure the strain the ground is under, in the form of small changes in the length of the cables as the ground is pushed and pulled by seismic waves.
The team set up an experiment in Iceland that used fibre-optic cables designed to transmit broadband, and transformed them into sensors for seismic waves created artificially.
Not only were the seismic waves created by the researchers detected, but the team was also able to determine the faults and other geological structures in the area.
“The results show it is possible get ground deformation measurements at a resolution of every few meters, compared to current seismic instrumentation that is often spaced many kilometres apart,” says Dr Elizabeth Cochran, a geophysicist with the US Geological Survey in Pasadena, California, who was not involved in the study.
Using cables that are already laid in the ground is also much cheaper than putting more equipment into the earth.
Cochran says the technique is unlikely to allow us to predict when an earthquake is going to strike. This is because there are currently no reliable precursory signals that can be used to predict earthquakes. “However, I do think that fibre optic cables may be able provide data that may speed up the detection of earthquakes for use in, for example earthquake early warning systems,” she says.
"We suggest that the networks of fibre-optic telecommunication lines worldwide could be used as seismometers opening a new window for Earth hazard assessment and exploration," the team says in the paper.
This article was originally published by WIRED UK
