The Teleseismic Tomography Experiment in the Eifel Region, Central Europe: Design and First Results

Abstract

The Eifel region is a mountain range belonging to the Rhenish Massif in central Europe. It is located in western Germany close to France, Luxembourg, and Belgium. The volcanic fields in the East Eifel and West Eifel (Figure 1) evolved in the last 600 ka, and the last eruptions occurred only 11-12 ka B.P. Twenty kilometers northwest of Koblenz the Laacher See volcano erupted at least 5 km3 of phonolitic magma (Bogaard and Schmincke, 1985) 12.2 ka ago—an amount that is comparable to the 1991 Pinatubo eruption. The intraplate volcanism in the Eifel region and the existence of further Tertiary volcanic fields in central Europe led Duncan et al. (1972) to the hypothesis that there is a hotspot track over an “Eifel plume.” Although the concept of this hotspot track is no longer accepted, various anomalies in the upper mantle support the existence of a mantle plume. Raikes and Bonjer (1983) revealed a low-velocity anomaly (∼-3%) at 50 km to 200 km depth beneath the Eifel region using teleseismic tomography. More recent tomographic images also contain a low-velocity zone in the upper 200 km of the mantle (Spakman et al., 1991; Passier and Snieder, 1997). Goes et al. (1999) proposed a deep magma source in the lower mantle based on global tomography. Meyer and Stets (1998) found evidence for up to 250 m uplift during the last 800 ka. Mineralogical and petrological studies indicate that the source of the magma is at least at 90 km depth. To obtain a detailed model of the processes in the upper mantle beneath the Eifel region a European interdisciplinary initiative was started. The scientific aim of the seismological contribution was to use all available techniques, such as high-resolution tomography, receiver functions, shear-wave splitting analysis, and crustal studies, to image the crust and …