Strike-slip Faults Imaging by Seismic Methods from Underground Galleries in the Station of Tournemire, France

Deep argillaceous formations are considered in many countries as potential host media for high-level long-lived radioactive waste due to their physical properties. In the experimental station of Tournemire, strike-slip faults with small vertical offsets were intercepted from underground galleries in the clay layer. Our aim is to assess the capacities and limits of high resolution seismic methods to detect and characterise the fault zones from underground works. Elastic Full Waveform Inversion (FWI) and Reverse Time Migration (RTM) are tested using original measurement configurations involving one, two or three perpendicular galleries. In the frame of numerical simulations, we show how RTM can detect only a part of the fault, and how FWI can provide a full or partial quantitative image of the fault zone depending on the measurement configuration.