The European Upper Mantle as Seen by Surface Waves

Abstract

We derive a global, three-dimensional tomographic model of horizontally and vertically polarized shear velocities in the upper mantle. The model is based on a recently updated global database of Love-and Rayleigh-wave fundamental-mode phase-anomaly observations, with a good global coverage and a particularly dense coverage over Europe and the Mediterranean basin (broadband stations from the Swiss and German seismic networks). The model parameterization is accordingly finer within this region than over the rest of the globe. The large-scale, global structure of our model is very well correlated with that of earlier shear-velocity tomography models, based both on body-and surface-wave observations. At the regional scale, within the region of interest, correlation is complicated by the different resolution limits associated to different databases (surface waves, compressional waves, shear waves), and, accordingly, to different models; while a certain agreement appears to exist for what concerns the grand tectonic features in the area, heterogeneities of smaller scale are less robustly determined. Our new model is only one step towards the identification of a consensus model of European/Mediterranean uppermantle structure: on the basis of the findings discussed here, we expect that important improvements will soon result from the combination, in new tomographic inversions, of fundamental-mode phase-anomaly data like ours with observations of surface-wave overtones, of body-wave travel times, of ambient ''noise'', and by accounting for an a-priori model of crustal structure more highly resolved than the one employed here.

Delamination or slab detachment beneath Vrancea? New arguments from local earthquake tomography

“…These findings generally corroborate the results obtained in previous tomographic studies [ Wortel and Spakman , 1992; Lorenz et al , 1997; Martin et al , 2005, 2006]. Our results are in qualitative agreement with S velocity model derived from inversion of surface waves by Boschi et al [2009] who found a slow heterogeneity under the Carpathians, underlain by a fast one, with the transition at ∼100–150 km depth. The tomography investigations using teleseismic data [ Wortel and Spakman , 2000; Martin et al , 2006] pointed out a well‐defined high‐velocity body extending down to a depth of about 400 km.…”

Seismic attenuation beneath Europe and the North Atlantic: Implications for water in the mantle

“…In Fig. S7 of the supplementary material we compare the isotropic shear wavespeed of EU 50 at a depth of 100 km with five surface-wave models, namely, EPmantle (Schivardi and Morelli, 2011), Chang2010 (Chang et al, 2010), S2.9EA (Kustowski et al, 2008b), LRSP30EU02 (Boschi et al, 2009) and CUSDT (Shapiro and Ritzwoller, 2002). Model EU 50 correlates well with these five models at this shallow depth.…”

Mesozoic and Cenozoic evolution of the Central European lithosphere

“…Receiver functions, in contrast, are used for the detection of sharp crustal and upper mantle discontinuities beneath seismic stations. (Trampert and Woodhouse 1995;Masters et al 2000;Zhou et al 2006;Peter et al 2008;Lebedev and van der Hilst, 2008;Boschi et al, 2009;Ritsema et al, 2011;Khan et al, 2011) and regional scales (Ritzwoller and Levshin 1998;Villasenor et al, 2001;Bruneton et al, 2004;Levshin et al, 2007;Weidle and Maupin, 2008;Legendre et al, 2012;Rickers et al, 2013), and also in body wave tomography on global (e.g. Grand et al, 1997;Grand, 2002) and regional (Spakman, 1990) scales.…”