Hydrological influences on long-term gas flow trends at locations in the Vogtland/NW Bohemian seismic region (German-Czech border)

U. Koch, J. Heinicke

Abstract


One of the typical methods for the identification of seismo-hydrological effects is to monitor changes in the free
gas flow throughout springs or mofettes. For several years, the gas flow regime of mineral springs at Bad Brambach
(Germany) and mofettes in the Nature Park Soos (Czech Republic) and its dependence on hydro-/meteorological
parameters have been studied. The mineral spring Wettinquelle, Bad Brambach, is a well-known seismo-
hydrologically sensitive location for swarmquakes at a special epicentral area of NW Bohemia. Since 2000,
a slight upward trend in the gas flow of three Bad Brambach mineral springs has been observed, which became
stronger after the Eisenquelle spring capture reconstruction (winter 2003/2004). Similar behaviour could be detected
at a mofette in Soos. The results correspond to a 3He/4He mantle ratio increase in gases at mofettes in the
Cheb Basin (CZ) traced by other authors for more than 12 years, and could give hints for a higher degassing activity
of the magma body below that area. Common and special properties in the degassing regimes of the Bad
Brambach and Soos locations are discussed. It is demonstrated that the long-term gas flow trend was interrupted
in 2003 because of very low groundwater levels. This effect was amplified by the artificial groundwater lowering
during the Eisenquelle spring capture reconstruction.

Keywords


seismo-hydrology;gas flow;groundwater level;mineral springs;mofettes

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References


DOI: https://doi.org/10.4401/ag-3069
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Published by INGV, Istituto Nazionale di Geofisica e Vulcanologia - ISSN: 2037-416X