The National Physical Laboratory (NPL) announced on Wednesday 24 April that scientists from NPL and the Measurement Standards Laboratory (MSL) in New Zealand are set to carry out the first ever optical interferometry-based earthquake sensing tests in the Pacific Ocean, using the Southern Cross NEXT cable.

NPL is the UK's National Metrology Institute (NMI) and a public corporation owned by the Department for Science, Innovation and Technology of the UK.

By performing ultra-sensitive optical measurements, scientists from the two laboratories will “convert” a seafloor cable extending offshore New Zealand into an array of sensors for earthquakes and ocean currents. These tests will lay the foundation for investigating the potential use of existing seafloor cables as detectors for tsunami early warning systems.

NPL first pioneered in 2021 and derived from techniques used for quantum science. It uses existing optical fibre infrastructure to gather continuous, real-time environmental data from the seabed. NPL previously demonstrated the technique in the Atlantic Ocean on a 5,860km-long intercontinental submarine optical fibre link between the UK and Canada.

NPL and the MSL will test the technique later this year on a section of the 3,876km-long Southern Cross NEXT cable on the floor of the Tasman Sea between New Zealand and Australia.

By applying NPL’s technique to a multitude of seafloor cables, thousands of ocean-bottom sensors could be implemented.

NPL’s sensing technique does not require any new hardware or infrastructure to be installed or any changes to existing infrastructure on the seafloor instead, it utilises the optical fibre itself as the environmental sensor. NPL’s technique has the potential to provide a valuable early warning system to safeguard coastal populations in the event of a tsunami. It also offers the first viable solution to fill the gap in data in ocean monitoring, with substantial impact in several scientific areas including seismology and oceanography.

Future projects could develop this concept into a worldwide monitoring network, giving earlier and more accurate detection of earthquakes and tsunamis, as well as advancing the world’s understanding of ocean floor geology and climate change through the long-term monitoring of seafloor temperature changes.

The project is part of a new collaboration agreement between the UK and New Zealand announced on Tuesday 23 April by Andrew Griffith, Minister of State for Science, Research and Innovation, at the Organisation for Economic Co-operation and Development (OECD)’s Committee for Science and Technological Policy Ministerial.