A subsea telecoms cable as a tsunami sensor — interferometry from NPL
On 22 September 2026 the UK’s National Physical Laboratory (NPL) reported that ultra-stable optical interferometry on a fibre of the Southern Cross NEXT cable provides data useful for early tsunami warning in the South West Pacific. The method uses an existing cable and needs no new seafloor installations.
- A laser sends ultra-stable light along the roughly 3,800 km cable linking New Zealand and Australia; signals return from amplifiers spaced about 50–70 km apart, and their changes reveal events such as earthquakes and ocean waves.
- The work is led by NPL, Earth Sciences New Zealand and New Zealand’s Measurement Standards Laboratory (MSL) together with the cable operator. The aim is to support the UN Ocean Decade Tsunami Programme goal of actionable forecasts within 10 minutes for many of the region’s tsunamis.
- According to MSL, the system installed in 2024 on a trans-Tasman cable detected signatures of more than 100 seismic events in its first year; funding from the Quantum Technologies Aotearoa programme until the end of 2028 is to improve its sensitivity.
- The Pacific Tsunami Warning and Mitigation System has set up a task team on forecasting from ocean observations to assess how such data can be brought into tsunami watch operations.
Source: National Physical Laboratory — Supporting early tsunami detection