Seafloor cables detect Pacific Ocean earthquakes

The team is 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 uses the optical fibre inside the cable as the sensing element and gathers environmental data from the seabed, where no other permanent sensors exist.

In a statement, Giuseppe Marra, principal scientist, NPL said: “We are very excited to have started detecting earthquakes and ocean currents in the Tasman Sea. This is the very first test of this technology in the Pacific Ocean and the waters surrounding New Zealand are the ’perfect laboratory’ to demonstrate the full potential of these…techniques for Earth sciences and coastal population protection.”

The Pacific Ocean is a highly seismically active area and since the start of the measurements in October 2024, the team has recorded over 50 earthquakes, with an epicentre from tens to hundreds of kilometres from the cable.

Using NPL’s technique, the team will be collecting measurements until December 2025, providing the potential to develop a worldwide monitoring network of seafloor sensors using the existing subsea infrastructure.

Over 70 per cent of the Earth’s surface is covered by water, but the ocean floor is largely unmonitored, thereby limiting humankind’s understanding of the Earth’s structure and dynamic behaviour. The sensing technique being tested in the Tasman Sea can counter this and improve understanding in several scientific areas.

GNS Science, New Zealand, will analyse the data to assess its potential for detecting tsunamis and explore how these new technologies can be complementary to more traditional approaches. According to NPL, the synergy between old and new techniques could improve the ability to respond to natural hazards.

The international collaboration has been enabled by the UK’s International Science Partnership Fund and is supported by New Zealand’s Quantum Technologies Aotearoa programme.

Bill Fry, seismo-tectonophysicist, GNS said: “This is an awesome and creative example of leveraging existing data sources and expertise from around the world to increase our eyes and ears in the vast expanse of the Pacific Ocean. We believe that adding these new cabled data will complement other rich data sources and collectively deliver faster and better tsunami warnings that will save lives in New Zealand and across the Pacific.”