Giuseppe Marra, Principal Scientist at the National Physical Laboratory, shares more about the new technique that has detected earthquakes in the Pacific Ocean.
Using a novel detection method which converts seafloor fibre optic cables into sensors for earthquakes, researchers have been able to successfully detect earthquakes in the Pacific Ocean.
Scientists from the National Physical Laboratory (NPL) and the Measurement Standards Laboratory (MSL) in New Zealand are performing ultra-sensitive optical measurements, converting a branch of the Southern Cross Next seafloor cable, which connects New Zealand to Australia, into an array of sensors for earthquakes and ocean currents. The technique, which is being tested in the Tasman Sea, uses the optical fibre inside the cable as the sensing element and gathers environmental data from the seabed, where no other permanent sensors exist.
The team first started taking measurements in October 2024 and will continue to do so until December 2025. Since they started, the team has already recorded more than 50 earthquakes in the Pacific Ocean. This high rate of detection will drastically accelerate the research and the refinement of the technique, which was previously tested in the less seismically active Atlantic Ocean.
At present, the ocean floor is predominantly unmonitored and this new measurement technique holds promise to uncover a wealth of data from existing seafloor infrastructure, which could significantly improve our ability to detect and respond to earthquakes and tsunamis globally.
To find out more about the research collaboration and what it means for our wider knowledge of earth science, The Innovation Platform spoke to Giuseppe Marra, Principal Scientist at NPL.
Can you explain more about the research collaboration and what it set out to achieve?
This new UK-NZ collaboration aims at testing our seafloor cable-based sensing technology in one of the most seismically active areas of the planet, the South-West Pacific. The work builds on our pioneering tests on a seafloor cable in the Atlantic Ocean, between the UK and Canada.
Here, we first demonstrated our innovative long-range sensing technology that enables us to monitor ocean signals across thousands of kilometres. The Atlantic Ocean is one of the best places to study ocean currents. However, the frequency of earthquakes in the Pacific is significantly higher and thus enables us to accelerate the research by being able to collect large amounts of geophysical data in a relatively short timeframe. The Tasman Sea, where the cable under test is located, is also statistically a better place to test the technique for early tsunami warning.
Can you explain how the technique works and how it was developed?
The technique enables the use of existing seafloor telecommunication cables as arrays of environmental sensors. This is achieved by performing ultra-precise optical measurements of the speed of light in the optical fibre inside the seafloor cables.
External environmentally-induced cable perturbations, such as earthquakes and ocean currents, can change the time that it takes for the light to propagate in the cable. These are incredibly tiny chances that can, however, be detected by ultra-precise measurements that labs like NPL are capable of.
The innovative technique was developed at NPL and derived from research on techniques for the comparison of distant optical atomic clocks via optical fibre links. When comparing clocks, the environmental noise is an unwanted disturbance that can corrupt the ultra-stable signals from the clocks and it is cancelled with some clever techniques. However, the unwanted noise for optical clock comparison contains very useful information for geophysicists. It’s a beautiful example of someone’s noise becoming someone else’s signal.
What do you expect and hope for the results?
The analysis of the data collected over the Tasman Sea cable, joining New Zealand to Australia, has just recently started and is being performed by GNS (New Zealand’s geophysical institute). We do expect significant results that can help us understand how these techniques can be integrated with existing techniques (such as seismic station on land) and in early warning systems in future.
Data from the UK-Canada cable has been fundamental in understanding the earthquake and ocean current capabilities of the technique and we are now working with oceanographers to understand how these data can help us better understand the ocean circulation and global warming.
At present, the ocean floor is largely unmonitored. Why is it important to change this?
The lack of permanent sensors on the seafloor limits our understanding of the Earth’s structure and dynamic behaviour. The lack of data is very significant, as 70% of the Earth is covered by water. For example, whilst we have ways of detecting surface currents from satellites and other surface sensors, seafloor currents are essentially unmonitored. With this technology, a much better understanding of the ocean current, which regulates the world’s climate, could be achieved.
What is the potential of ocean monitoring technology in terms of the wider impact?
The technology is a gamechanger for advancing research in Earth sciences such as seismology and oceanography. However, in a not too distant future, it could pave the way to much better alerting systems for the coastal population in case of off-shore earthquakes and tsunamis. This is one of the main aspects that the researchers at GNS are looking at when analysing the data from the Southern Cross cable between New Zealand and Australia. The technology could potentially save lives in future in case of natural disasters and have a significant positive impact on coastal populations.
What is next for the research collaboration?
Both collaborations in the Atlantic and Pacific Oceans have laid the foundations for a new era for Earth monitoring. These pioneering tests are showing that it is indeed possible to use the existing telecommunication infrastructure to expand our monitoring capabilities from land to the oceans. Through these collaborations, we want to continue to push the limits of what these technologies can do and provide new tools to better understand our planet and, crucially, provide new possible solutions for positive social impact, from the protection of coastal populations from natural disasters to advancing climate change research.
Please note, this article will also appear in the 22nd edition of our quarterly publication.
