A robust prediction of recent crustal stress is critical for selecting sites and designing high-level radioactive waste repositories, ensuring their long-term safety and environmental protection. It is also vital for underground activities like hydrocarbon or geothermal energy production. However, while the World Stress Map offers comprehensive information about the orientation of maximum horizontal stress for Germany, reliable stress magnitudes are only accessible in specific areas. To overcome this challenge of limited data availability, geomechanical-numerical modelling is used. Another challenge is, that the crustal stress field is influenced by factors of varying scales, such as plate boundaries and topography. This poses a challenge for numerical stress prediction, as there is a conflict between model size, resolution, and computing resources. Small-scale models offer high resolution but lack incorporation of large-scale influencing factors, while large-scale models have limited resolution.
To solve this, we use models of different scales - a regional model of 200 * 80 km2 with 12 units and a site model of 20 km * 60 km2 with 18 units and a submodeling approach, combining them to achieve a comprehensive understanding of crustal stress distribution. The research area locates between Baden-Württemberg and Bavaria, covering Teilgebiet 001 in the Molasse basin, focusing on the Opalinus clay with maximum thickness 300 meters. The regional model is calibrated using a Germany-wide stress model, which then calibrates the site model. This submodeling approach extrapolates stress tensors from the larger area to a potential site model, reducing time and resources.