Seismic monitoring lasers may be the future for protecting global communications cables

The depths of the oceans are home to a complex ecosystem of marine organisms, but also a vast network of cables spanning the globe that aid communications. Earthquakes and tsunamis can potentially damage these important cables. The Earth's surface is more than 70% water, which creates a challenge for scientists who monitor this seismic activity.

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A recent study by researchers at Geo-Ocean and their collaborators reported in Earth and Planetary Science Letters have used laser technology, termed Brillouin optical time domain reflectometry (BOTDR), to monitor the structural health of these cables in near real time.

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The scientists used a remotely operated vehicle to deploy a 6-km-long cable to measure strain 2,100 meters below the sea surface. It was attached to an enormous 29-km-long fiber optic cable in order to measure earthquake activity offshore of Catania, Sicily. This involved firing a laser (comprising hundreds of thousands of pulses over two hours) through one end of the fiber optic cable and detecting the points at which the light scattered off imperfections, highlighting areas where the cable was deformed in some way.

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The novel use of the laser technology may mean that seismic activity could be identified in advance of an earthquake and allow time for planning strategies that could mitigate damage to life, infrastructure and our communications.