Methods and some results of investigations of the scattering properties in the crust and mantle

Results derived from analyses of mainly forward-scattered seismic waves are reported. Major findings are that the strongest scattering originates in the crust and upper and lower mantle, while the central parts of the mantle appear relatively homogeneous. In the upper mantle the extent of the heterogeneities exhibits regional variations. Interestingly, scattering observations do not appear to be time-invariant in certain regions, thus being indicative of active evolutionary processes.