In the context of the ICDP project DSeis we perform a systematic study on the composition of all free circulating gases extracted from a fault zone during seismic cycles and thus, make a qualitative and semi-quantitative analysis of the volatile components in fractured crystalline rocks at earthquake focal depth.
The experiments are performed in a ~600 meter long borehole intersecting an active fault zone in the Roodpoort Quartzite located 3.4 km below land surface in the Moab Kotsong mine, South Africa. We plan to detect changes in the chemical composition during seismic activity and the interaction with the microbiological community.
With the chemical and isotopic characterization of the individual fluids before and after seismic activity we hope to clarify the origin of hydrogen and its migration, i.e. if seismic events provide new pathways for migration of already existing gases or hydrogen and other gases are synthesized mechanochemically during seismic events.