This volume contains papers presented at an international workshop at the Chateau of Trest, Czech Republic in 1996. The workshop brought together geophysicists and geologists who work in the fields of observational and theoretical seismology, gravity studies and geodynamic modelling. Topics include: large-scale anisotropy of the Earth's mantle; mantle heterogeneity versus anistropy 3-D velocity and density structures and inferences on mantle dynamics; mineral and rock physics studies; and mathematical aspects of complex wave propagation.