The Eifel is a huge volcanic area, Magma is located below the Laacher See. Researchers argue for an early warning system in Germany and a reassessment of the threat situation.
The quiet and idyllic Laacher Lake is surrounded by forests and meadows in the Eastern Eifel. Only rising gas bubbles in the eastern bank remind us that a volcano lurks beneath the body of water. And that is still very active, as researchers have first documented. In a survey since 2013, they found eight series of low-frequency earthquakes ranging from 10 to 45 kilometers deep. These are indications that magmatic liquids from the upper mantle under the Laacher See volcano can currently reach the earth's crust, they write in the "Geophysical Journal International".
Boats float on a jetty at Laacher See. A volcano is still lying beneath the body of water, which is still very active, as researchers have first documented. (Source: dpa)
"The Eifel volcanism is not extinguished, it is long-term sleep," says first author Martin Hensch, geophysicist at the Landeserdbebendienst Baden-Württemberg in the Regierungspräsidium Freiburg. The movements of the fluids in depth can be interpreted as an indication that magma chambers in the earth's crust are being filled up slowly. But the seismic series did not mean that a volcanic eruption was imminent, emphasizes co-author Torsten Dahm of the German Research Center for Geosciences (GFZ) in Potsdam.
"Reacting threat situation"
At the last outbreak almost 13,000 years ago, the filling of the upper magma rooms took about 30,000 years. "This means that the magmatic processes can take place for very long periods before an eruption occurs," the researchers emphasize, which also include employees of the Karlsruhe Institute of Technology and the State Soil Service North Rhine-Westphalia.
Rhineland-Palatinate, Maria Laach: the aerial photo with a drone shows the Laacher See. The Eifel is the most active volcanic area in Germany. (Source: dpa)
The study shows that it is important to "take a closer look and re-evaluate the threat situation," Dahm says. Eruptions were announced, such as volcanic gas and surface deformation. The question is when exactly and for how long such signals occur – "and whether we can measure them". The researchers recommend, in addition to the monitoring network of the Seismological Service, to intensify the monitoring of the escaping gases and the measurements of possible changes in the earth's surface.
The measured earthquakes in the Eastern Eifel below 40 km depth are "the lowest ever measured in the earthquake in Germany," he says. In general, deep low-frequency (DLF) tremors occur at greater depths in this area and have lower frequencies than tectonic earthquakes. DLF earthquakes are interpreted worldwide as an indication of movement of magmatic fluids and are regularly observed among active volcanoes, for example in Iceland, Japan or on the Russian Kamchatka Peninsula.
450 small and large volcanoes
It is unclear, according to Hensch, since when there are such earthquakes under the Laacher See. The monitoring network in Rhineland-Palatinate has only expanded considerably over the past ten years. "Since then, we have been able to measure and find reliable earthquakes." However, it is clear that similar activities already existed before.
Horses graze for the benedictine abbey Maria Laach in Laacher See. Although an eruption in the Eifel is unlikely at the moment, researchers are asking for a reassessment of the threat in Germany. (Source: dpa)
According to geophysicist Dahm, the volcanism of the Eifel is unique in Germany because it is very young. The youngest volcano in Germany is there: the Ulmener Maar was built around 11,000 years ago. "The other zones are not really comparable because they are all older." Only in the Oberpfalz, especially in the German-Czech border area, there are still examples of CO2Degassing on the basis of magmatic processes in the upper casing.
"The Eifel is the largest volcanic area in Central Europe", says Andreas Schüller, Managing Director of the Nature and Geopark Vulkaneifel in Daun. "She is riddled like a Swiss cheese." A total of about 450 small and large volcanoes witnessed outbreaks that had repeatedly moved the low mountain ranges for more than 40 million years. Most were only active for a short time. The results of the investigation do not disturb the expert. "I can see that very relaxed."
No volcano monitoring system in Germany
The eruption of the volcano below the Laacher See around 13,000 years ago was the "last violent volcanic eruption in Central Europe": at that time about six cubic kilometers of material had been emitted – ash deposits could be detected in southern Sweden and northern Italy.
"The evaluation of former explosives centers in the Eastern Eifel suggests that the activity phase of the Laacher See volcano is not yet at an end and may continue to erupt in the future," Dahm says. The danger in Germany must also be recaptured because of the repository problem. "In Germany there is no volcano monitoring system yet, which would be handy." Experts in a workshop of the German Volcanological Society on February 28 and March 1 in Mendig want to tell how that could look like.