Scientists at the National Physical Laboratory (NPL) have discovered a new technique that can turn undersea power and telecom cables into arrays of environmental sensors, opening the door to expanded ocean monitoring.
The findings, published in Scientific magazinecould revolutionize the way we monitor our planet by providing real-time environmental data from the seabed.
Despite advances in sensor technology, much of the world’s oceans remain unmonitored due to the high costs and technical challenges associated with installing and maintaining permanent sensors on the ocean floor. This lack of monitoring leaves a significant gap in geophysical data, limiting our understanding of Earth’s structure and dynamic behavior.
Detecting tsunamis
Previous research by NPL and its partners has shown that submarine cables can be reused as sensors to detect underwater earthquakes. However, each cable could only function as a single sensor and measurements were limited to changes over the entire length of the cable.
The new research shows that certain cables can be turned into an array of sensors instead of just one. The team, consisting of researchers from the University of Edinburgh, the British Geological Survey, the Istituto Nazionale di Ricerca Metrologica and Google, tested the technology on a 5,860 km submarine fiber optic link between Great Britain 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 link. Each optical fiber span acted as a sensor, with up to twelve sensors deployed along the cable.
This groundbreaking research could potentially enable the monitoring of large areas of the ocean floor that are currently unmonitored, transforming underwater telecommunications infrastructure into a wide range of geophysical sensors.
Furthermore, the research suggests that this method could potentially be used to detect tsunamis. By enabling the real-time detection of tsunami-inducing earthquakes closer to their offshore epicenter, this technology could provide crucial additional warning time and potentially save lives. The research team now plans to test this method on multiple submarine cables, including cables in more seismically active areas such as the Pacific Ocean.
We spoke to Giuseppe Marra, lead researcher at NPL, about the new technique.
Is it theoretically possible to perform triangulation with the cables?
Yes. Multiple cables can be used to identify the epicentral region of the earthquake, in a similar manner to terrestrial seismometers. Because we ‘convert’ each cable into an array of sensors, rather than a single sensor, you can calculate the epicentral area with just one cable, and the resolution can be improved with multiple cables.
Can the cable be used to simultaneously transfer the collected data?
Yes, data traffic may be present on the other channels of the same fiber optic. This was actually the case during our testing and it is an important aspect for the expansion of this technology to many cables around the world. We used a cable intended for intercontinental internet traffic, we did not use special cables for this study.
Or can it only be used as sensors?
According to the above, the same cable can be used for both data and sensing. No change is required to the underwater cable infrastructure and therefore this technology is potentially the first viable solution to the lack of ocean floor data (as we do not have permanent seafloor sensors).