  Velocity structure of the lithosphere-asthenosphere system, to the depth of
about 350 km, is obtained for almost 400 cells, sized 1 degree by 1 degree in
the Mediterranean region. The models are obtained by the following sequence of
methods and tools: surface-wave dispersion measurements and collection; 2D
tomography of dispersion relations; non-linear inversion of cellular dispersion
relations; smoothing optimization method to select a preferred model for each
cell. The 3D velocity model, that satisfies Occam razor principle, is obtained
as a juxtaposition of selected cellular models. The reconstructed picture of
the lithosphere-asthenosphere system evidences the, globally well known,
asymmetry between the W- and E-directed subduction zones, attributed to the
westward drift of the lithosphere relative to the mantle. Different
relationship between slabs and mantle dynamics cause strong compositional
differences in the upper mantle, as shown by large variations of seismic waves
velocity, consistent with Polarized Plate Tectonics model.
