Large-scale electrical resistivity tomography in the Cheb Basin (Eger Rift) at an ICDP monitoring drill site to image fluid-related structures

0509184 - GFÚ 2020 RIV DE eng J - Journal Article
Nickschick, T. - Flechsig, C. - Mrlina, Jan - Oppermann, F. - Löbig, F. - Günther, T.
Large-scale electrical resistivity tomography in the Cheb Basin (Eger Rift) at an ICDP monitoring drill site to image fluid-related structures.
Solid Earth. Roč. 10, č. 6 (2019), s. 1951-1969. ISSN 1869-9510. E-ISSN 1869-9529
Institutional support: RVO:67985530
Keywords : Western Bohemian Massif * earthquake swarms * Central Europe
OECD category: Volcanology
Impact factor: 2.921, year: 2019
Method of publishing: Open access
https://www.solid-earth.net/10/1951/2019/

The Cheb Basin, a region of ongoing swarm earthquake activity in the western Czech Republic, is characterized by intense carbon dioxide degassing along two known fault zones – the N-S-striking Počatky-Plesná fault zone (PPZ) and the NW-SE-striking Mariánské Lázně fault zone (MLF). The fluid pathways for the ascending CO2 of mantle origin are subject of an International Continental Scientific Drilling Program (ICDP) project in which several geophysical surveys are currently carried out to image the near-surface geologic situation, as existing boreholes are not sufficiently deep to characterize the structures. As electrical resistivity is a sensitive parameter to the presence of low-resistivity rock fractions as liquid fluids, clay minerals and also metallic components, a large-scale dipole-dipole experiment using a special type of electric resistivity tomography (ERT) was carried out in June 2017 in order to image fluid-relevant structures. We used static remote-controlled data loggers in conjunction with high-power current sources for generating sufficiently strong signals that could be detected all along the 6.5 km long profile with 100 m and 150 m dipole spacings. Extensive processing of time series and apparent resistivity data lead to a full pseudosection and allowing interpretation depths of more than 1000 m. As electrical resistivity is a sensitive parameter to the presence of conductive rock fractions as liquid fluids, clay minerals, and also metallic components, a large-scale dipole-dipole experiment using a special type of electric resistivity tomography (ERT) was carried out in June 2017 in order to image fluid-relevant structures. We used permanently placed data loggers for voltage measurements in conjunction with moving high-power current sources to generate sufficiently strong signals that could be detected all along the 6.5 km long profile with 100 and 150m dipole spacings.
Permanent Link: http://hdl.handle.net/11104/0299940