Swiss Alps 3D: building a large-scale 3D underground model of the Central European Alps

The Swiss Geological Survey (SGS) is the competence centre for the subsurface and georesources of the Swiss Confederation. It provides up-to-date, high-quality spatial reference data for the whole of Switzerland in the form of nationwide geological datasets and 3D geological models. Between 2024 and 2030, the SGS is funding the Swiss Alps 3D project, which consists of eight research projects involving multiple universities and aims to develop a consistent large-scale 3D geological model of the main contacts and structures of the Swiss Alps.

In this poster we present the complete workflow that will be used for the construction of this 3D model and the project plan for the next 7 years. The main challenge for 3D modelling in Alpine regions is the lack of subsurface data (seismic, boreholes, etc.). However, the high relief, the sparse vegetation and the large number of scientific studies make these regions an excellent site for advanced surface-based 3D modelling. Based on the new Tectonic Map of Switzerland 1:500'000 (2024, in prep.), the area is divided into eight 3D modelling projects according to their paleogeographic origin and structural evolution. The resulting models will then be merged into a single large-scale 3D model.

At the beginning of each modelling project, a 1:25’000 scale geological map of the main structural and lithostratigraphic contacts will be produced by verifying and harmonising a 2D geological dataset compiled for the study (published maps, strike and dip data, tunnel and seismic data). 3D modelling software packages (e.g., Move™, SKUA-Gocad) will be then used to generate a network of regularly spaced (1000 m) geological cross sections throughout the area. By applying explicit or implicit 3D interpolation and meshing techniques between the cross sections and the surface outcrop lines (i.e., spline curve method), lithological and structural boundaries will be then interpolated to generate 3D surfaces of each horizon of the model. The workflow presented here offers the chance to gain validation approaches for domains only weakly constrained or with no subsurface data available, by generating a 3D model that integrates all accessible geological information and background knowledge.

Swiss Alps 3D will generate key knowledge by establishing an experienced modelling community and 3D visualization of the main structures and lithostratigraphic boundaries of the Central European Alps. The development of such a model will provide a framework model of the area as a basis for higher resolution 3D models to be used for infrastructure planning, groundwater studies, natural hazard assessment, education and research purposes. In addition, such models will provide access to strategic subsurface knowledge for geo-resource and geo-energy management and exploration.