**Researchers have detected earthquakes in the Pacific Ocean for the first time using a subsea telecommunications cable.**
The Southern Cross Next seafloor cable, which connects New Zealand to Australia, was converted 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.
Measurements only started in October, but the team has already recorded more than 50 earthquakes in the Pacific Ocean even when the epicentre was tens to hundreds of kilometres from the cable.
The National Physical Laboratory (NPL) team says the high rate of detection could “drastically accelerate” the research and the refinement of the technique, which was previously tested in the less seismically active Atlantic Ocean.
Measurements will be collected until the end of this year, after which it is hoped the technology could be adapted to develop a worldwide monitoring network of seafloor sensors using the existing subsea infrastructure.
Tsunami experts at GNS Science in New Zealand will also analyse the data to assess its potential for detecting tsunamis and improve their ability to respond to natural hazards that threaten coastal communities.
Giuseppe Marra, NPL principal scientist, said: “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 innovative cable-based ocean monitoring techniques for Earth sciences and coastal population protection.”
Dean Veverka, CTO of Southern Cross Cables, said: “Recently we have seen, and the Pacific islands have experienced, the impact that natural disasters can have on communities and livelihood. Early detection of earthquakes and changes in the seabed can enable communities to better prepare for, and protect against, these natural events.”
While over 70% of the Earth’s surface is covered by water, the ocean floor is largely unmonitored, limiting understanding of the Earth’s structure and dynamic behaviour. The sensing technique could help to fill the existing data gap and improve understanding in a number of science areas, from seismology to oceanography and climate change.
In February, Meta announced plans [to build the world’s longest](https://eandt.theiet.org/2025/02/18/meta-plans-worlds-longest-subsea-data-cable-connect-five-continents) subsea data cable, which will link the US with India, South Africa, Brazil and other regions along the route.