The Earth's structure and the geod) nam ic processes that originate it are strictly interconnected: an accurate knowledge of the Earth·s structure and its physical properties is fundamental for the understanding of the dynamics of our planet and critical for realistic simulations of seismic ground motion. On the other side the separation and the definition of the different dynamic processes acting in a certain area help to better understand the structure and the physical properties of the investigated region. In recent years much emphasis has been given to the inversion or observed phase and waveform data for the best fitting set or model parameters at a variety of scale-lengths.