Undersea Internet Cables Could Detect Quakes, Tsunamis

Internet cables that crisscross the sea-floor could be used to detect earthquakes and tsunamis or monitor how climate change alters ocean currents, Chris Vallance reported for BBC.

Photo Insert: The researchers said they had detected earthquakes and "ocean signals", such as waves and currents, using a 5,860 km EXA Infrastructure optical-fiber link between Southport, Lancashire, and Halifax, Canada.

These telecoms cables could be used as a giant array of deep-sea scientific sensors, the UK's National Physical Laboratory (NPL) and its partners say. Scientists tested the technique on an optical-fiber link between the UK and Canada. The research was published in Science magazine.

Since installing permanent sensors to monitor the ocean floor is very costly, only a few exist globally, the scientists say."Seventy percent of the Earth's surface is water but all the seismic stations are on land because it is too difficult and expensive to install permanent sensors on the seafloor" Dr. Giuseppe Marra of the NPL told the BBC.

Numerous optical-fiber cables carry data across the world's seas and oceans. It is estimated there are more than 430 around the world, spanning distances of 1.3 million km (800,000 miles).

According to Marra, vibrations, pressure, and temperature changes affect, by a very small amount, the speed of light as it travels through the cable which extremely sensitive instruments can then detect.

The researchers said they had detected earthquakes and "ocean signals", such as waves and currents, using a 5,860 km EXA Infrastructure optical-fiber link between Southport, Lancashire, and Halifax, Canada. The scientists were able to use individual spans of cable between repeaters - devices that help boost the signal - as separate sensors.

“If we apply this technique to a large number of cables", Dr Mara said "we could transform this underwater infrastructure into a giant array of detectors for earthquakes, ocean currents, and more. Extending the seismic network from land to the seafloor will improve our understanding of the internal structure of the Earth and its dynamic behavior."

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