Dynamics of fluid flow in Westbohemia/ Vogtland: Imaging and Detection (Bohemian FluID)

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Within the ICDP-Eger Rift the installation of three seismic 3D arrays will form a major component of the comprehensive laboratory to observe and investigate the geodynamic processes in the region West Bohemia/ Vogtland. In this proposal, we will permanently install the surface part of one 3D array and provide an additional temporary mobile array for seismological observations at strategic points. The project will seismically investigate and image the temporal and spatial evolution of deep (several kilometres) fluid pathways in the region West Bohemia/Vogtland by using the ambient seismic noise field generated by fluid movements. We will employ matched field processing (MFP), a processing approach aiming at imaging and detecting noise sources in the subsurface by comparing synthetic and recorded seismic wavefields. In previous studies, MFP has been identified as a useful tool to investigate the temporal and spatial distribution of noise sources related to fluid flow in the shallow subsurface. We will further develop MFP to enhance its capabilities to image and detect several kilometres deep noise sources. In the project, we will use seismological data recorded by a permanent surface array to be installed at the ICDP drilling location S1 near Landwüst (Vogtland), by a temporary mobile array and by downhole installations as soon as they will be available. We focus on two target regions located South and North of the Nový Kostel focal zone. In the South of Nový Kostel, recent seismological and magnetotelluric studies identified a fluid channel for which a direct link to the earthquake swarms occurring in this region was proposed. The region North of Nový Kostel showed an increased shallow earthquake activity (less than 8 km) within the last few years and is currently active. As the observations in both regions are potentially linked to fluid flow in the crust, we will further develop and use MFP to investigate the spatio-temporal behaviour of these phenomena. For this purpose, we will employ multi-array analysis, weight input data to enhance imaging capabilities, and include a priori information concerning complex velocity models in the processing. In parallel, we will collect long-term continuous observations of deep seated fluid pathways in the target regions using multiple arrays which will be investigated with special emphasis on the temporal changes in relation to the occurrence of earthquake swarms. Overall the proposal aims to enlarge the methodological tool box available to investigate the geodynamic processes related to deep fluid flow and swarm earthquakes in the region West Bohemia/ Vogtland in the ICDP-Eger Rift.