Fluctuations of gas concentrations in three mineral springs of the East Eifel Volcanic field (EEVF)

TL;DR

This study analyzes gas fluctuations in mineral springs over 7 months to identify tectonic fault linkages and assess volcanic activity in the East Eifel Volcanic Field using geochemical and statistical methods.

Contribution

It reveals previously unknown fault linkages through gas correlation analysis and evaluates the influence of tectonic and environmental factors on gas emissions.

Findings

Nette and K"arlich are linked via a tectonic fault.

Kaerlich and Kobern are connected through a NNE-SSW fault system.

No evidence found for weather or earth tides modulating degassing.

Abstract

We present a geochemical dataset acquired during continual sampling over 7 months (bi-weekly) and 4 weeks (every 8 hours) in the Neuwied Basin, a part of the East Eifel Volcanic Field (EEVF). We used a combination of geochemical, geophysical, and statistical methods to identify potential causal processes underlying the correlations of degassing patterns of four gases (He, Rn, CO2, O2), earth tides, and tectonic processes in three mineral springs (Nette, Kaerlich and Kobern). We explored whether temporal relations in gas concentrations in the three mineral springs could be indicators of hidden faults through which the gases migrate to the surface from deeper underground. Our results do not confirm CO2 as a primary carrier gas for trace gases in all springs. Temporal analyses of the CO2-He couple indicate that Nette and K\"arlich are directly linked via a continuous tectonic fault in an ENE-WSW trending direction. There is also evidence that Kaerlich and Kobern (NNE-SSW fault system) and Nette and Kobern (NW-SE fault system) are tectonically linked. These fault linkages are unknown previously but could be related to the rising numbers of earthquake events occurring in this area since 2010. We did not find any evidence that weather processes (e.g., barometric pressure), earth tides, or low local earthquake magnitudes actively modulate degassing. The volcanic activity in the EEVF is dormant but not extinct and to understand and monitor its magmatic and degassing systems, we recommend bi-weekly samplings at minimum.