Global SV wave upper mantle model

We present a summary of all our seismological models based on surface wave observations. First, wen have updated our global SV model that is based on the waveform modelling of more than 3 millions Rayleigh waves recorded since 1976. The tomographic model is built using the same automated scheme as was presented in Debayle et al., GRL 2016, while the number of data has increased by a factor larger than 2. Second, we present new SV wave velocity and radial anisotropy, ξ, global model obtained from the joint inversion of multi-mode Rayleigh and Love wave data. The Rayleigh dataset has been also used in previous studies to constrain the azimuthal anisotropy, the quality factor Q and the melt content. All these models are based on self-consistent datasets and have been obtained with similar regularization and smoothing. All together they confirm that (1) there is no age dependence of the radial anisotropy ξ in the oceanic lithosphere while age is the main parameter controlling Vsv, (2) Positive (ξ > 1) radial anisotropy extends deeper (down to 300 km depth) beneath oceans than beneath continents (3) melt content and azimuthal anisotropy have a significant dependence with age under oceans, particularly under fast plates, (4) cratons appear fast, melt-free and anisotropic, down to 250-300 km depth for the azimuthal anisotropy and down to 150-200 km for the radial anisotropy, a depth coinciding with the detection of a positive velocity gradient, (5) ξ ≤ 1 anomalies are present in the deeper part of the cratonic roots (200-250 km) that could reflect past delamination or compression of the deep lithospheric roots. Out of these observations, we propose a conceptual model that enables reconciling a number of seismic observations. Finally, will present our new online tool (https://fascil.univ-lyon1.fr/) available to explore these tomographic models and to compare with existing ones.