Velocity modelling across borders: Insights from the TUNB Velo 2.0 project

During the TUNB Velo 2.0 project, the State Geological Surveys of Schleswig Holstein, Lower Saxony, Mecklenburg Western Pomerania, Brandenburg and Saxony-Anhalt together with the Federal Institute for Geoscience and Natural Resources (BGR) developed a large-scale seismic velocity model for the North German Basin. The structural model of the previous TUNB project formed the basis for modelling. However, the project partners did not use a consistent classification of geological layers when assigning the interval velocities. Furthermore, different methods were used for creating the volume model and its parametrization. Additionally, input datasets for the velocities varied between project partners. All these differences necessitate the harmonization of the velocities at the borders to have a consistent regional model. The harmonisation methods were tested in a pilot region and differ for each border. Velocities were mainly consistent between Lower Saxony and Schleswig-Holstein because we used the same regional velocity model as a basis. With Mecklenburg Western Pomerania, the theoretical surface velocities and gradients were interpolated to harmonize the interval velocities. For Brandenburg and Saxony-Anhalt, a weighted interpolation of the interval velocities in a buffer zone was applied.

On the poster, we present an overview of the harmonization strategies applied along the borders between Lower Saxony and its neighbours. We highlight different border-specific approaches and illustrate how we achieved regional consistency despite varying methodologies and datasets. Selected results from the pilot region demonstrate the effectiveness of the applied methods and their impact on building a coherent velocity model for the North German Basin.