Undersea Cables Are Watching for the Next Big Quake

Nokia Bell Labs and University of Washington scientists turn underwater telecom cables into advanced acoustic sensors for earthquake monitoring

27 May 2026

Researchers from Nokia Bell Labs and the University of Washington have converted several hundred kilometres of existing undersea fiber optic cables into a working seismic monitoring network, detecting earthquake activity along the Cascadia subduction zone off the Pacific Northwest coast of the United States.

High-loss loopback couplers, small devices installed within standard signal repeaters, allowed the team to overcome a longstanding technical barrier: the limited distance over which light signals travel in fiber lines without degradation. By repurposing equipment already embedded in the cables, the researchers avoided laying new infrastructure.

Over the course of the trial, 3.9 terabytes of acoustic data were generated and used to map undersea geological activity in a region considered one of North America's highest-risk seismic zones. Cascadia, where the Juan de Fuca tectonic plate slides beneath the North American plate, is capable of producing magnitude-9 earthquakes and the tsunamis that follow.

For telecom operators, the approach offers environmental monitoring capacity from infrastructure they already own and maintain. Coastal communities could gain an upgrade to existing early-warning systems without the cost of dedicated ocean-floor sensor arrays, which can run into tens of millions of dollars per installation.

Questions remain about data processing speeds and integration with national seismic alert systems. Whether telecoms will move to formalise dual-use agreements with government agencies has not been established.