3D geological and geotechnical subsurface model for the Einstein Telescope study area in Sardinia (Italy)

The Einstein Telescope (ET) research infrastructure is envisioned as Europe’s pioneering next-generation underground observatory for gravitational-wave detection.Its engineering design requires a multi-criteria approach capable of identifying and addressing geological, geotechnical, environmental, and landscape challenges. To manage these complexities, the ET-3G Lab at Sapienza University of Rome (as part of the ETIC PNNR project), has produced an advanced digital multi-scale 3D model for the Sardinia site identified as a potential location.The model integrates surface and subsurface data at both regional and local scales, consolidating all available geological, geophysical, and geotechnical datasets to support a coherent reconstruction of key subsurface features, including lithotypes, faults, and fracture networks. It incorporates data from surface observations and drilled calibration wells, encompassing geological and petrophysical information, laboratory tests on undisturbed samples, fracture analyses, and geophysical investigations conducted by the ET scientific community. This integrated representation strengthens the linkage between surface and subsurface information.As a result, a comprehensive 3D geological model of the ET Sardinia site has been developed, enabling visualization of the subsurface down to a depth of approximately one kilometer.This advanced modeling approach is intended to support the minimization of geotechnical risks, the optimization of construction strategies and associated costs, and the implementation of scenario-based design analyses.