Undersea telecom cables can be used as earthquake monitoring networks: Study

Fibre-optic cables that make up global undersea telecommunications network may help researchers assess offshore earthquakes, and hidden geologic structures in depths of ocean, according to a study. 

study, published in journal Science, describes an experiment which turned a 20 kilometre section of undersea fibre-optic cable into equivalent of 10,000 seismic stations monitoring quakes along ocean floor.

researchers, including those from University of California (UC) Berkeley in US, recorded a 3.5 magnitude earthquake, and seismic scattering from underwater fault zones during ir four-day experiment.

y used a technique where a device with components for creating, manipulating and detecting light sent short pulses of laser down cable, and detected how this was backscattered due to strain in cable caused by stretching. 

researchers n measured scattering at every two metres of cable, and turned a 20-kilometre section into 10,000 individual motion sensors.

y said technique could be used to map a previously unkwn fault system, and observe several dynamic tidal and storm-driven processes in water column above.

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technique called Distributed Acoustic Sensing, was earlier tested with fibre-optic cables on land, but can w be used to obtain data on quakes happening under sea, where few seismic stations exist, y said.

researchers said new system is sensitive to changes of nametres to hundreds of picometres for every metre of cable length -- a change happening at scale of one part in a billion. 

"re is a huge need for seafloor seismology. Any instrumentation you get out into ocean, even if it is only for first 50 kilometers from shore, will be very useful," said study lead author Nate Lindsey from UC Berkeley.

scientists hope to use dense fibre-optic networks around world, spanning more than 10 million kilometers, on both land and under sea to measure sensitive seismic movements on Earth. 

"This is really a study on frontier of seismology, first time anyone has used offshore fibre-optic cables for looking at se types of oceagraphic signals or for imaging fault structures. One of blank spots in seismographic network worldwide is in oceans," said study co-author Jonathan Ajo-Franklin from Rice University in US.

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(Story picture: Pinterest / Sean Corwin)