Cables That Feel The Earth Move

Fiber-optic lines built for data may double as tsunami detectors, raising hopes and questions about dual-use ocean infrastructure

13 Feb 2026

At the bottom of the ocean, where the world’s internet quietly runs, a new role is emerging. Researchers have shown that a working 4,400km submarine cable can do more than carry emails and video streams. It can also sense earthquakes and the tsunamis that follow.

In a recent demonstration scientists applied a technique known as distributed acoustic sensing to an operational fibre-optic line. When a magnitude-8.8 earthquake struck, the cable registered both the seismic waves and the ensuing tsunami more than 600 miles offshore. By sending pulses of light through the fibre and analysing tiny disturbances in the signal, the team effectively turned the cable into around 44,000 virtual sensors spaced every 100 metres.

The achievement does not herald an immediate industry standard. It shows what is technically possible, not what is yet common practice. Still, the implications are hard to ignore. Submarine cables carry more than 95% of global data traffic. They are already threaded across fault lines and tectonic boundaries, especially in the seismically active Asia-Pacific region. Earthquakes and underwater landslides are persistent threats to these networks. The ability to detect disturbances in real time could help operators respond faster and plan maintenance more efficiently.

There are broader benefits. Tsunami-warning systems rely on sparse arrays of seabed instruments and coastal gauges. Existing telecoms cables, if equipped to sense their surroundings, could extend monitoring far into the open ocean, buying coastal communities precious minutes of warning.

Yet turning cables into sentinels brings complications. The equipment required is costly. Data governance and cybersecurity safeguards would need to be robust. Monitoring must not interfere with core transmission services. Cable owners may hesitate to assume new public-safety responsibilities without clear incentives.

Investment in subsea infrastructure is rising, fuelled by cloud computing, streaming and artificial intelligence. At the same time governments are demanding greater resilience from critical systems. The convergence is timely. If sensing capabilities can be integrated from the design stage, future cables may be judged not only by the data they carry, but by the dangers they detect.