Real-time fluid monitoring of the Eifel volcanic fields

The emplacement of fresh magma at depth should be detectable with an appropriate fluid monitoring strategy. Eifel volcanic fields are accompanied by hundreds of CO2-rich springs and mofettes. Fluids can ascent at velocities of several 100 m/d through the crust, leading to estimated travel times of several months from the lower crust to the surface. Thus, online monitoring is mandatory to catch potential fluid transients related to magmatic processes at depth – in addition to repeated sampling campaigns for the isotopic composition of the gases. Monitoring targets are fluid emission sites with high CO2 concentrations and increased mantle helium signatures. In November 2020, real-time fluid monitoring started with focus on the East Eifel. As of today, ten sites are operative including abandoned CO2 wells, mofettes, CO2-rich springs, as well as a coldwater geyser in the West Eifel. Wellhead pressure or water level are measured at sampling rates up to 1 Hz, while water temperature, conductivity, and radon concentration are measured in 1 to 5 minute intervals. We report on short-term (several days) and long-term (several years) pressure transients in the fluid system. The latter are tentatively related to the recovery of a formerly exploited CO2 reservoir in the East Eifel as predicted from a physical model capable to explain observed local ground deformation above the reservoir. The presented examples demonstrate the need for a synoptic interpretation of meteorological, hydrogeological, geophysical, and geodetic data to provide the basis for an assessment of the activity state of the Eifel volcanic fields.
The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)