PEGGHy: A controlled geological environment to challenge geophysical instruments and imaging methods

When testing new imaging methods, researchers often rely on synthetic cases. These latter usually consist of a reference geomodel in which data are computed so that the methods can be challenged. To make these data realistic, noise is added, whose features can be questionable. Moreover, geomodels are simpler than real geological environments because they cannot contain the whole spectrum of geological scales. To circumvent these issues, we have developed the Platform for Experimental Geophysics, Geotechnics and Hydrogeology (PEGGHy), which holds artificial, fully controlled geological structures and heterogeneities. PEGGHy is filled with aggregates which have been selected based on their lithological properties so that significant geophysical contrasts are expected. Moreover, PEGGHy contains local anthropic heterogeneities which can generate wave diffraction and small-scale anomalies. Thanks to photogrammetric data acquired by drone, PEGGHy goes with a 3D, centimetric precision digital twin. Such a numerical tool allows to quantitatively compare models derived from geophysical data with the true subsurface geometry, providing a unique opportunity to test and teach instrumentation and imaging strategies.