Delineation of the geometries of magmatic structures beneath the East Eifel Volcanic Field (Germany) Using 3D Gravity and Magnetic Inversion

The East Eifel Volcanic Field (EEVF) in western Germany comprises numerous scoria cones, maars, and lava domes, with recent geodetic measurements revealing uplift rates of up to ~2 mm/yr. Deep low-frequency earthquakes indicate ongoing magmatic processes and transcrustal melt pathways. To refine the understanding of the geometry and volume of potential magmatic structure, we present a 3D gravity and magnetic inversion of the uppermost crust beneath the EEVF.

Initially, synthetic forward modeling evaluated the detectability of magma bodies of varying sizes and depths, considering realistic density and susceptibility contrasts. We then applied advanced gravity data processing methods—namely terracing and clustering—to highlight subtle anomalies and improve interpretability prior to inversion. The subsequent inversion of the Bouguer gravity anomaly and total magnetic intensity data employed a flexible regularization scheme that balances smoothness and compactness, enabling realistic imaging of magmatic accumulations. As potential-field data alone is non-unique, we plan to incorporate results from local earthquake tomography provided by the ongoing Large-N seismic experiment in the Eifel. Notably, preliminary tomographic results suggest a cylindrical anomaly approximately 3 km in diameter extending from near-surface to ~10 km depth beneath the Laacher See. These seismic constraints will help reduce ambiguity in the final model by offering well-resolved information at shallow to mid-crustal depths and correlating known structures in both gravity and tomography. 

The resulting 3D model will illuminate the lateral and vertical extents of structures origination from magmatic processes beneath the EEVF, advancing our knowledge of its transcrustal magmatic system. This work will also inform future scientific drilling under the ICDP-EIFEL initiative, where new boreholes and monitoring efforts aim to clarify volcanic processes in this intraplate volcanic region.