Phase velocities of Rayleigh and Love waves in central and northern Europe from automated, broadband, inter-station measurements – Implications for the lithosphere-astenosphere structure on both side of the Transeuropean Suture Zone
The increasingly dense coverage of Europe with permanent and temporary broadband seismic stations makes it possible to image its lithosphere and asthenosphere structure in great detail, provided that structural information can be extracted effectively from the very large volumes of data. In a new implementation of the classical two-station method, Rayleigh and Love dispersion curves are determined by cross-correlation of seismograms from a pair of stations. Between 5 and 3000 single-event dispersion measurements are averaged per inter-station path in order to obtain robust, broad-band dispersion curves with error estimates. In total, around 63000 Rayleigh- and 27500 Love-wave dispersion curves between 10 s and 350 s have been determined, with standard deviations lower than 2 % and standard errors lower than 0.5 %. Using our large new dataset, we construct phase-velocity maps for central and northern Europe. According to checkerboard tests, the lateral resolution in central Europe is ≤ 150 km. The new, broad-band, phase-velocity dataset offers abundant, valuable information on the structure of the crust and upper mantle beneath Europe. In our contribution we present and discuss results, which shed new light on the lithosphere-asthenosphere structure across the Transeuropean Suture Zone spanning from the Variscan European Platform towards the Proterozoic East European Platform. Comparison of regional surface-wave tomography with independent data on sediment thickness in North-German Basin and Polish Trough (from a compilation of deep seismic sounding results) confirms the accuracy of the imaging using our short-period, phase-velocity measurements. The region of the Tornquist- Teisseyre Zone is associated with a stronger lateral contrast in the lithospheric thickness from the East European Platform towards the southwest compared to the region across the Sorgenfrei-Tornquist Zone as can be clearly seen from the longer periods.