Global seismic tomography: The inverse problem and beyond

Global seismic tomography has produced a great amount of robust information concerning the three-dimensional extent of the Earth's internal structure. This has stimulated a multidisciplinary discussion aimed at understanding the mechanisms which govern the internal evolution of our planet. A brief overview of seismic tomography is presented. Since geodynamical understanding is the main purpose of seismic tomography, some suggestions are made on how to evolve from a predominantly qualitative to a more quantitative interpretation of its results. We argue that without a more systematic and realistic error and resolution analysis, interpretations might be misleading. Assuming a steady increase of data quality and coverage, the most challenging aspect of seismic tomography will be to take the nonlinearity of the problem fully into account. It is hoped that this contribution stimulates some discussion in that direction.