Scientists at the National Physical Laboratory (NPL) have discovered a novel technique that can turn undersea power and telecom cables into arrays of environmental sensors, opening the door to extensive ocean monitoring.
The findings, published in Science Magazine, could revolutionize the way we monitor our planet by providing real-time environmental data from the seafloor.
Despite advancements in sensor technology, much of the world's oceans remain unmonitored due to the high costs and technical challenges of installing and maintaining permanent ocean-floor sensors. This lack of monitoring leaves a significant gap in geophysical data, limiting our understanding of the Earth's structure and dynamic behavior.
Detecting tsunamis
Previous research by NPL and its partners demonstrated that submarine cables could be repurposed as sensors to detect underwater earthquakes. However, each cable could only function as a single sensor, and measurements were confined to changes over the cable's entire length.
The new research shows that certain cables can be converted into an array of sensors rather than just one. The team, including researchers from the University of Edinburgh, the British Geological Survey, the Istituto Nazionale di Ricerca Metrologica, and Google, tested the technique on a 5,860 km-long submarine optical fiber link between the UK and Canada, provided by EXA Infrastructure.
The team detected earthquakes and ocean signals, such as waves and currents, on individual spans between repeaters across the entire transatlantic connection. Each optical fiber span acted as a sensor, with up to 12 sensors implemented along the cable.
This groundbreaking research could potentially enable the monitoring of vast areas of the ocean floor currently unmonitored, by transforming underwater telecoms infrastructure into a vast array of geophysical sensors.
Moreover, the research suggests that this method could potentially be used for detecting tsunamis. By enabling the real-time detection of tsunami-inducing earthquakes closer to their offshore epicenter, this technology could provide crucial additional warning time, potentially saving lives. The research team now plans to test this method on multiple submarine cables, including those in more seismically active areas such as the Pacific Ocean.
We spoke to Giuseppe Marra, Principal Research Scientist, NPL, about the new technique.
Is it possible, in theory, to do triangulation with the cables?
Yes. Multiple cables can be used to identify the epicentral area of the earthquake in a similar way as with land seismometers. As we “convert” each cable into an array of sensors, rather than a single sensor, you can already work out the epicentral region with one cable, and the resolution can be improved with multiple cables.
Can the cable be used to transfer the data it collects at the same time?
Yes, data traffic can be present on the other channels of the same fiber. This was actually the case during our tests and it is an important aspect for the expansion of this technology to many cables around the world. We have used a cable that is for intercontinental internet traffic, we did not use any dedicated cables for this research.
Or can it only be used as sensors?
Following the above, the same cable can be used for both data and sensing. No change is required to the underwater cable infrastructure and this is why this technology is potentially the first feasible solution to the lack of data from the ocean bottom (as we don’t have permanent sea floor sensors).
