3D geological modelling at the Swiss Geological Survey: Development of national-scale models

Within the framework of the National Geological Model (NGM), a long-termed federal program (2022–2030), the Swiss Geological Survey (swisstopo) is developing a series of three-dimensional geological models at national scale. The primary objective is to achieve full spatial coverage of Switzerland with harmonized 2D and 3D geological models representing the geometry of major tectonic structures, lithostratigraphic units, and the bedrock surface. These models form a consistent geological framework that supports sustainable subsurface use and long-term spatial planning.

Switzerland comprises three principal geological domains with contrasting structural styles and stratigraphic architectures: the Jura fold-and-thrust belt, the Foreland Plateau, and the Alpine orogenic domain. These domains differ significantly in terms of deformation mechanisms, lithological complexity, data availability, data type and depth of geological investigation. This requires domain-specific modelling strategies and tailored approaches to uncertainty management. In addition, subsurface utilization and associated societal demands, such as infrastructure development, groundwater management and hazard assessment, vary markedly between regions.

The 3D modelling group at swisstopo has implemented a domain-based modelling strategy by subdividing Switzerland into three regional modelling areas corresponding to the main geological domains. For each domain, regional-scale 3D geological models are constructed through the integrated interpretation of surface geological maps, borehole and geophysical data, cross-sections and geological concepts and constraints. These models provide a consistent structural and stratigraphic framework that translates traditional geological mapping into digital, reproducible subsurface representations suitable for national-scale applications.

This contribution presents an overview of the current status of four complementary modelling projects developed by the 3D Group at the Swiss Geological Survey: swissBEDROCK, Jura3D, GeoMol, and swissAlps 3D.

swissBEDROCK provides a nationwide 3D bedrock model of Switzerland based on an automated and reproducible workflow with explicit uncertainty representation and regular versioned updates. Jura3D focuses on high-resolution structural and stratigraphic modelling of the folded and thrust-faulted sedimentary sequences of the Jura fold-and-thrust belt. GeoMol addresses the Foreland Plateau at regional scale, emphasizing stratigraphic architecture and basin geometry. swissAlps 3D targets the structurally complex Alps, with a strong emphasis on the tectonic development of the main lithostratigraphic and structural units supported by scientific argumentation. This contribution further highlights the importance of collaborative workflows involving federal and cantonal authorities, academia, and private partners in the development of consistent national 3D geological models.

These projects together illustrate how diverse geological modelling approaches are integrated within a coherent national framework. Moreover, they bring together geological knowledge and 3D modelling workflows across contrasting geological domains.