Global surface wave tomography

I will present an overview of the state-of-art surface wave analysis which consists of three steps: (i) The measurement of the average dispersion between source and receiver (or between two receivers on the same great circle path) based on a non-linear waveform inversion. (2) The construction of anisotropic phase velocity maps which summarises the measurements on the sphere. (3) The local depth inversion of the phase velocity maps for elastic parameters. At each step, uncertainties are evaluated and all parameters are expressed in terms of probability density functions. Examples will show a global crustal model, transition structure and probabilities of anisotropy in the upper and lower mantle.