The mantle though solid is in a state of rheic convection. This convection process causes the lithospheric plates to move, albeit slowly. The resulting process is known as plate tectonics. Volcanoes result primarily from the melting of subducted crust material or of rising mantle at mid-ocean ridges and mantle plumes. https://category-environment09753.mybuzzblog.com/1485125/asbestos-removal-northampton-grundlagen-erklärt