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Telecom Business Review | Thursday, March 23, 2023
New research has suggested that with fibre optic cables used for internet access under the sea, earthquakes can be detected half an hour earlier than current methods.
FREMONT, CA: Underwater fibre optic cables are capable of detecting earthquakes within a half-hour of their occurrence, which is an advantage over current approaches. Early earthquake warning systems can be provided via optical communication fibres, including fibres from commercial communication providers, as has been proven.
Several existing solutions are being implemented in Japan, such as the enhancement of land-based seismic networks and the deployment of ocean-based sensor networks that are wired. As these solutions are expensive, they cannot be used everywhere. The use of new acoustic sensor technology to transform existing fibre optic cables into dense seismic networks is one alternative. Using the current fibre infrastructure will cut warning times and simplify and speed up seismic warning system installation and operation. Every year, several earthquakes happen all around the world. While most are harmless and small, strong ones can cause widespread destruction. Sea-based earthquakes are typically only detected ten seconds after they begin, although contemporary seismic monitoring technology can give early warning for land-based earthquakes.
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Much of the worldwide traffic on the internet uses fibre optic cables to connect distant continents along the ocean floor. With Google's global network of underwater cables, information can be exchanged, searched, sent, and received faster than ever before. These cables are made of optical fibres, which transmit data as light pulses moving at a speed of 204,190 kilometres per second. As the pulsing light travels thousands of kilometres across the cable, distortions are encountered. The light pulses are recognised at the receiving end, and digital signal processing is used to correct any distortions. The degree of polarization is one of the characteristics of light that are monitored as part of optical transmission (SOP). We can identify seismic activity by tracking the mechanical disturbances along the cable that causes the SOP to vary.
The measuring oscillations in the polarisation of such deep-sea cables offer a cheap, quick substitute for time- and money-consuming seismological research at the bottom of the sea. There are many submarine cables available to read this type of data from. The entire network of undersea cables could circle the earth 20 times, while the cable is only approximately four-fifths of its circumference.
The geometry of the first seismic stations that are used for earthquake location, specifically its geographical spreading and distance to the source, has a significant impact on the effectiveness and reliability of the earthquake and tsunami monitoring system, which must respond only a few minutes after the event onset.
The cable networks might refine images of the Earth's interior in addition to mapping earthquakes. Big earthquake seismic waves, like the x-rays in a computed tomography (CT) scan, carry hints about the density of the rock they pass through. Seismologists can create 3D images of mantle convection, in which hot plumes surge up and cold tectonic plates descend towards Earth's core, from crisscrossing waves picked up by numerous sensors. Data from seafloor cables could fill up blind regions in these seismic CT scans.
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