| I propose to develop and apply a novel technique for seismic tomography that better constrains density variations in the Earth?s upper mantle. In contrast to the classically estimated velocity variations, density remains largely unknown due to data and methodological limitations. The new method will be based on (1) recently available high-quality seismic data that serve as input, and (2) our newly developed full waveform inversion technology that exploits information from complete seismograms. Through the design of misfit functionals, specifically targetted at the detection of density heterogeneities, we will progress beyond standard seismic data analysis. The refinement of our recently invented resolution analysis tools will provide objective quantifications of our state of knowledge on density structure. For the first time in full waveform inversion, we will sample the model space, thereby providing a range of plausible Earth models, instead of one single deterministic solution. The assimilation of independent data from gravity and mineral physics will further tighten our constraints on density variations. Concrete outputs of this research will be (1) a new methodology for density tomography, and (2) a density model with uncertainties for the European upper mantle. This project will establish a new line of seismic tomography and a new generation of Earth models. Our results will contribute to the resolution of long-lasting debates, including the impact of convection on surface deformation, the distribution of chemical heterogeneities, the nature of continental lithosphere and the origin of surface-geochemical signatures. Moreover, our methodological developments will be transportable to exploration and engineering applications. |
