Anisotropy and seismic velocities of Opalinus Clay and surrounding rock formations — SI-A and SI-B experiments

In the context of the characterization of potential host rock formations for nuclear waste repositories, and also for the investigation of cap rocks for energy storage, or in the support of large underground infrastructure projects, the high-resolution seismic investigation of clay rock formations in the underground is filling the gap between large-scale surface geophysical surveying and boreholes. Internal heterogeneities, or the degree of elastic anisotropy, are properties which ideally require direct but as much as possible non-destructive observations from within the formation. The Mont Terri rock laboratory (MTRL), providing excellent accessibility conditions for in-situ experiments within the Opalinus Clay, and including surrounding formations, has enabled various seismic characterization experiments, investigating the elastic properties and anisotropy of these formations at various scales.