Crustal deformation and deep magma source beneath the Eifel volcanic fields from Large-N seismic experiment

The Eifel volcanic fields represent one of the most prominent expressions of the Cenozoic volcanism in Central Europe. Volcanic activity has occurred episodically since ~40 Ma, with the most recent major eruption at ~13 ka producing highly explosive, gas-rich magmas. The Eifel comprises two Quaternary subfields, each extending over approximately 60×40 km² and hosting numerous volcanic centers. The occurrence of deep low-frequency earthquakes, crustal seismicity, active degassing and continuous regional uplift indicate ongoing magmatic processes. Using data from the recently deployed Eifel Large-N passive-source seismic experiment, which involved ~500 seismic stations of different sensor types, we image the structure of the crust and mantle lithosphere beneath the Eifel volcanic fields using receiver functions. Our results reveal significantly lateral variations in crustal thickness that reflect Variscan orogenic structures subsequently modified by Cenozoic volcanism. The Moho depth decreases from northwest to southeast across the Siegen Thrust and is locally uplifted by up to ~5 km beneath the two Quaternary volcanic fields, reaching depths of ~28 km. The crystalline basement is elevated by ~3 km beneath the East Eifel, indicating substantial crustal exhumation. Beneath the East Eifel, the lithosphere is thinned to ~40 km and spatially correlates with the occurrence of deep low-frequency earthquakes. Together, these observations are consistent with asthenospheric upwelling, which likely facilitates magma generation and fluid migration associated with Eifel volcanism.