In its first months of test operations in Alaska and the Russian Far East, the system operated by the University of Washington spotted two eruptions a full hour before they showed up on satellite images, The Seattle Times reported Tuesday.
The churning clouds unleashed by explosive volcanic eruptions generate lightning, which antennas can identify by their distinctive low-frequency radio signatures.
Such detections could provide valuable warning time for aircraft, whose engines can fail when clogged with volcanic ash.
"If we're able to get an extra 30 or 60 minutes more of a heads-up, it could be a real contribution," vulcanologist John Ewert of the U.S. Geological Survey's Cascades Volcano Observatory said.
UW space-sciences professor Robert Holzworth has managed the World Wide Lightning Location Network since 2004, expanding it from a handful of stations to 52 around the world.
More than 3 million lightning strokes are logged by the system every month, and only a tiny fraction are from volcanoes.
But those are fairly easy to spot because they're usually not associated with a storm, Holzworth said.