Germany's Eifel Volcanoes Show Surprising Signs of Underground Activity

Inside the Eifel Volcanoes Revealed

A glimpse into fiery depths: In the Eifel region, geoscientists have completed Germany's largest volcanological measurement experiment—a seismic scan of the volcanic area. The findings show that the magma reservoir beneath Laach Lake lies deeper and extends differently than previously thought. The data also reveal where and how thousands of microquakes in the Eifel originate, hinting at the presence of magma or volcanic fluids beneath the surface.

December 19, 2025

Beneath the Eifel lies a hidden volcanic hotspot—a volcanic field whose last major eruption, around 13,000 years ago, blanketed half of Europe in ash. Since then, the Eifel volcanoes have been considered dormant—at least in theory. But recent evidence suggests growing volcanic activity underground. The region is rising, swarms of minor earthquakes are becoming more frequent, and seismic data point to reservoirs of magmatic fluids beneath the surface.

500 Seismic Stations and a Fiber-Optic Cable

What does this mean? Could it signal the reawakening of the Eifel supervolcano? To find out, researchers conducted Germany's largest seismological volcanic experiment between September 2022 and August 2023. A team led by Thorsten Dahm of the GFZ German Research Centre for Geosciences installed around 500 seismic stations across the Eifel region for this large-N experiment. In the East Eifel volcanic field, these stations were spaced roughly one kilometer apart on average.

Additionally, the researchers used a 64-kilometer-long, unused fiber-optic cable. Such underground cables can also function as seismic sensors because the light signals in the fiber react with extreme sensitivity to even the slightest tension, stretching, or compression. These movements appear as characteristic distortions and scattering effects in the transmitted light pulses.

First Detailed Look at Laach Lake Volcano's Magma Chamber

The results are now in. While they confirm some assumptions about the structure and state of the Eifel volcanoes, they also reveal unexpected findings. For the first time, the new data pinpoint the exact location, position, and depth of the magma reservoir responsible for the Laach Lake eruption 13,000 years ago. "We now have the first high-resolution tomographic image of the upper 14 kilometers beneath the Laach Lake volcano," Dahm and his team report.

The data show that this volcano's magma reservoir lies at a depth of about ten kilometers—significantly deeper than previously believed. Furthermore, the seismic anomaly beneath the Eifel volcano is oriented differently than assumed: rather than descending vertically, it slopes toward the Neuwied Basin. "This channel-like anomaly, roughly three kilometers in diameter, extends from the Laach Lake volcano at a 53-degree angle toward the southeast into the depths," the researchers explain.

Origin of Earthquake Swarms Revealed

New insights have also emerged regarding the thousands of microquakes in the Eifel region and possible fluid accumulations in the crust. Most of the weak tremors occurred along a narrow, vertical zone between Laach Lake and Ochtendung. However, there are also earthquake clusters concentrated at the edges of seismic anomalies—zones where seismic waves travel faster or slower than usual. According to the researchers, this could indicate elevated temperatures or pressure in these areas.

"Unusually strong reflections of seismic waves at layer boundaries in the upper and lower crust beneath the Neuwied Basin are also notable," Dahm says. "The intensity of these reflections suggests that fluids have accumulated in these layers." Whether these fluids are magma or magmatic in nature remains unclear and will be investigated further using improved analytical methods.