BRUSSELS, 30 September — Scientists say a cluster of earthquakes and a rapid rise in volcanic gas around Laacher See could signal magma moving beneath the Eifel region, about 130 km (81 miles) from Belgium. A paper published on Wednesday says an eruption within 30 days cannot be ruled out, though its authors stress that the evidence does not establish a countdown.
The warning follows Tuesday’s recall of 1,860 gas analysers made by Belgian firm Vulkasense. Researchers found the devices understated carbon-dioxide readings during sharp spikes; 74 had been used at monitoring sites around the volcanic lake. A research team rechecked the archived measurements against laboratory samples and found that emissions had climbed to more than four times their July level.
Corrected readings change the picture
The revised figures sit alongside 620 small earthquakes recorded in the past 14 days, compared with 21 during a typical fortnight, and 6.4 cm (2.5 inches) of ground uplift measured over 18 days. The paper’s authors say those changes, together with a shift in the helium isotope ratio, are consistent with gas from deeper underground, but could also reflect changes in the volcano’s hydrothermal system.
“We have moved from a background concern to a near-term warning, but nobody can put a reliable date on an eruption,” said Drąsius Žeimantas, a volcanologist on the study team. Its conditional model estimates a 15% chance of an eruption in the next 30 days if the seismic and gas trends continue; the authors say that figure is not a formal forecast.
The instruments did not invent this signal; they blurred its sharpest part.
Drąsius Žeimantas, volcanologist
Laacher See last erupted about 12,900 years ago. A repeat on a similar scale could send ash high into the atmosphere, the researchers say. Their wind-dependent worst-case model leaves up to 2 cm (0.8 inches) of ash in parts of eastern Belgium, with thinner deposits farther west; even a smaller eruption could close nearby airspace and foul water intakes.
Officials hold back evacuation plans
Belgian officials urged people not to cancel travel or stockpile supplies. Nora Gunnarsson, a spokesperson for the national crisis centre, said there was “no present basis for an evacuation order” and that German monitoring agencies had not declared an eruption imminent. She said the centre was reviewing the paper and would update local authorities if the alert level changed.
That reassurance has not quieted researchers. The study says the monitor flaw means earlier gas readings cannot be treated as a dependable baseline, and warns that a fresh surge could develop faster than routine reporting cycles catch it. The authors called for round-the-clock sampling and daily publication of seismic, gas and ground-movement data.
Belgium’s civil-protection service is discussing precautionary plans with provincial authorities, including public guidance on ash, checks of drinking-water supplies and advice for airports. No restrictions have been announced. The study estimates that a large plume could force airspace closures for several days, while fine ash might also slow road and rail freight moving between Germany, Belgium and the North Sea ports.
The recall covers devices sold to laboratories and monitoring contractors since 2023, Vulkasense said, and replacement units are due to be shipped within two weeks. Emeriks Liepkalne, who lives near Liège and works in freight scheduling, said her firm had already asked customers to prepare alternate routes. “If the air corridors close, the trucks will fill the gap — until the roads fill up too,” she said.
Researchers say the next 72 hours matter: German teams are installing independent instruments around the lake, while the study’s authors plan to release recalibrated historical readings next week. For now, officials are asking residents to follow verified alerts rather than forecasts circulating online, as scientists watch for whether the ground continues to rise.
