Updated stress data compilation

Structural diversification of the geomechanical model for Germany

The new geomechanical numerical model of Germany has the same dimensions as the two previous versions of Ahlers et al. (2021, 2022) and the same workflow is used. The main improvement is the implementation of 27 geological models for a new stratigraphic subdivision of the sedimentary unit, an increased vertical resolution and the extended magnitude database used for calibration. The model contains 49 geological units parametrized with individual elastic rock properties (Young’s modulus and Poisson’s ratio) and rock densities. Overall, the model contains ~10 million hexahedral elements providing a lateral resolution of 4 km and a vertical resolution of up to 45 m in the uppermost 5 km.

Preliminary results shown an overall good fit with stress magnitudes used for calibration indicated by a mean of the absolute stress differences of ~3 MPa for Shmin and of ~5 MPa for SHmax. Furthermore, the results agree well with additional data sets – not used for calibration – e.g., an absolute mean deviation of the orientation of SHmax with regard to WSM data of ~10°. The higher vertical numerical resolution, the increased stratigraphic resolution and the extended calibration dataset enable a significantly improved and more robust prediction of the recent crustal stress state. Both, the geological model and results of the geomechanical-numerical model will be published soon.

Slip Tendency analysis

The stress data provided by the updated model is used to calculate the potential of faults to be reactivated. A compilation of geological models provides 3D geometries of faults for large parts of Germany. By mapping the stress data of the updated model onto these fault geometries, a first order estimate of the fault reactivation potential is facilitated. One widely used measure for the fault reactivation potential is the slip tendency. The slip tendency is the ratio of the maximum resolved shear stress to the normal stress acting on the fault plane (Morris et al. 1996). Small slip tendency values close to 0 indicate that a fault is unlikely to be reactivated whereas higher values indicate that faults are more likely to be reactivated.

The compiled 3D fault geometries are color-coded by the slip tendency. A hydrostatic pore pressure was used for the slip tendency calculation.

References:

Ahlers, S., Röckel, L., Hergert, T., Reiter, K., Heidbach, O., Henk, A., Müller, B., Morawietz, S., Scheck-Wenderoth, M., and Anikiev, D.: The crustal stress field of Germany: a refined prediction, Geotherm Energy, 10, https://doi.org/10.1186/s40517-022-00222-6, 2022.

Ahlers, S., Henk, A., Hergert, T., Reiter, K., Müller, B., Röckel, L., Heidbach, O., Morawietz, S., Scheck-Wenderoth, M., and Anikiev, D.: 3D crustal stress state of Germany according to a data-calibrated geomechanical model, Solid Earth, 12, 1777–1799, https://doi.org/10.5194/se-12-1777-2021, 2021.

Morawietz, S., Heidbach, O., Reiter, K., Ziegler, M., Rajabi, M., Zimmermann, G., Müller, B., and Tingay, M.: An open-access stress magnitude database for Germany and adjacent regions, Geothermal Energy, 8, https://doi.org/10.1186/s40517-020-00178-5, 2020.

Shapefiles Countries: © EuroGeographics for the administrative boundaries

Publications:

Ahlers, S. and Henk, A.: 3D Geological Model for Germany and Adjacent Areas, Earth Syst. Sci. Data, 2025, submitted.

Contact: Steffen Ahlers