Subsea Internet Cables Could Help Detect Earthquakes

Ocean covers over two-thirds of the surface of the earth. The seas can be dim and murky places where reliable data are hard to come by. Just because oceans are mysterious doesn't mean they lack infrastructure. More than 750,000 miles of telecommunications are spread across the oceans. They help the internet cross continents. Now, scientists are trying to play with that infrastructure to detect earthquakes and seismic hazards.

The UK's National Physical Laboratory (NPL) and its partners have stated that internet cables that crisscross the sea floor might be used to detect earthquakes and tsunamis or monitor how climate change alters ocean currents. Scientists believe telecom cables might be used as a giant array of deep-sea scientific sensors. They tested the technique on an optical-fiber link between the UK and Canada, and the research was published recently.

As installing permanent sensors to monitor the floor of the oceans is costly, just a few of those exist. Dr. Giuseppe Marra of the NPL said: "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 sea floor."

Still, it is estimated that there are over 430 optical-fiber cables carry data across the world's seas and oceans and span distances of 1.3 million km (800,000 miles)

Dr. Marra believes that pressure, vibrations, and temperature changes slightly affect the speed of light as it travels through the cable, which sensitive instruments can detect. The researchers detected earthquakes and "ocean signals," like waves and currents, using a 5,860km EXA Infrastructure optical-fibre link between Southport, Lancashire, and Halifax, Canada. The scientists used individual spans of cable between repeaters as separate sensors. The repeaters are devices that help boost the signal.

Dr. Marra said, "If we apply this technique to a large number of cables, 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 sea floor will improve our understanding of the internal structure of the Earth and its dynamic behavior."

The researchers highlighted that cable-based sensors could identify an earthquake's "epicentral area" similarly to land-based seismometers. This technique has also opened other possibilities, like monitoring deep-water currents for changes that are caused by global warming. The cables can also monitor how climate change alters sea-floor temperatures.

Brian Baptie, head of the Earth seismology team for the British Geological Survey, said, "It creates an amazing opportunity to observe earthquakes in the middle of oceans at close range as well as the tantalizing possibility of measuring other natural phenomena like submarine volcanic eruptions and tsunami in future."

As this is a first demonstration and not a working system, a lot of work still needs to be done. First, the scientists will have to understand better the deluge of complex data generated by monitoring SOP. Researchers need advanced mathematics and data analytics to create a robust earthquake monitoring system.


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