Scientists at the National Physical Laboratory (NPL) have discovered a novel technique that can turn underwater power and telecommunications cables into arrays of environmental sensors, opening the door to comprehensive monitoring of the oceans.
The findings, published in science magazinecould revolutionize the way we monitor our planet by providing real-time environmental data from the seafloor.
Despite advances in sensor technology, much of the world's oceans remain unmonitored due to the high costs and technical challenges of installing and maintaining permanent sensors on the ocean floor. 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 showed that undersea cables could be repurposed as sensors to detect undersea earthquakes. However, each cable could only function as a single sensor and measurements were limited to changes over the entire length of the cable.
New research shows that certain cables can be turned into a series of sensors instead of just one. The team, made up of 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 kilometer-long submarine fiber optic link between the United Kingdom and Canada, provided by EXA Infrastructure.
The team detected earthquakes and ocean signals, such as waves and currents, in individual spans between repeaters along the entire transatlantic connection. Each stretch of fiber optic acted as a sensor, with up to 12 sensors deployed along the cable.
This groundbreaking research could potentially enable monitoring of vast areas of the ocean floor that are currently unmonitored, transforming underwater telecommunications infrastructure into a wide range of geophysical sensors.
Additionally, research suggests that this method could potentially be used to detect tsunamis. By enabling real-time detection of tsunami-causing 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 undersea cables, including those in areas with higher seismic activity, such as the Pacific Ocean.
We spoke to Giuseppe Marra, principal research scientist at NPL, about the new technique.
Is it possible, in theory, to do triangulation with cables?
Yes. Multiple cables can be used to identify the epicentral area of the earthquake in a similar way to ground seismometers. As we “convert” each lead into an array of sensors, rather than a single sensor, the epicentral region can now be computed with one lead and the resolution can be improved with multiple leads.
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. In fact, this was the case during our tests and 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 cable for this research.
Or can it only be used as sensors?
Following the above, the same cable can be used for both data and detection. No change to the submarine cable infrastructure is required and that is why this technology is potentially the first viable solution to the lack of ocean floor data (as we do not have permanent sensors on the sea floor).
