Subsea internet cables could help detect earthquakes

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

Scientists tested the technique on an optical-fibre link between the UK and Canada.

The research is published in Science Magazine.

"70% 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.

But numerous optical-fibre 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).

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

Cable-based sensors could identify the "epicentral area" of an earthquake in the same way as land-based seismometers, the researchers suggest.

And the technique opened other possibilities, such as monitoring deep-water currents for changes caused by global warming.

There is also the untested possibility of using cables to monitor how climate change alters sea-floor temperatures.

Technology-giant Google was involved in the research as well as the University of Edinburgh, the British Geological Survey, and the Istituto Nazionale di Ricerca Metrologica, in Italy.