INTEGRATED 3D GEOLOGICAL MAPPING AND MODELLING OFFERS COUNTRYWIDE KEY KNOWLEDGE OF THE SUBSURFACE IN SWITZERLAND

The brand-new 1:500’000 scale Tectonic Map of Switzerland, published by the SGS, represents a major update of the geometry, distribution and nomenclature of the tectonic units in Switzerland and neighboring regions. Unlike the previous version (2005), the map is based on a uniform data model, which allows a consistent and accurate description of the present configuration of the tectonic units (e.g., geometry and the nature of their contacts).

Such database with paleogeographic and structural hierarchical classes (1st to 4th order) serves as an ideal input for any large-scale project intended to unravel the tectonic and geological structure of the country.

This is the case of the Swiss Alps 3D project (SA3D), which aims to produce a consistent, large-scale underground 3D geological model of the main contacts and structures in the Swiss Alps by 2030. Here, the Tectonic Map serves as a reference for a uniform interpretation of the subsurface on a large scale and for targeting the units to be modelled.

In fact, based on such data model, SA3D has been divided into eight 3D modelling projects, which will eventually be merged into a single large-scale 3D model. Within each project, the target structural and lithostratigraphic contacts are modelled at the equivalent scale of 1:25’000. A network of regularly spaced (1000 m) geological cross sections and scientific concepts, discussed and reviewed by the different modelling teams, are then developed to strengthen the modelling techniques.

The workflow developed for SA3D 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 multiscale geological data unified by a common dataset provided by the Tectonic Map.

The development of such a model, and the establishment of datasets such as the Tectonic Map of Switzerland, provide framework models 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.

SA3D seamlessly fits into the overall 3D geological modelling program, which aims to cover the country with a digital 3D dataset by the end of 2030.