[Rockhounds] Subsea internet cables could help detect earthquakes

[Kreigh Tomaszewski]

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

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-fibre link between the UK and
Canada.

The research is published in Science Magazine.

Because installing permanent sensors to monitor the ocean floor is very
costly, only a few exist globally, the scientists say.

"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 <https://www.submarinecablemap.com/> 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 Dr 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 5,860km EXA Infrastructure
optical-fibre 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.


https://www.bbc.com/news/technology-61506705