Earth is a dynamic planet, in which active faults cause earthquakes, and volcanoes produce lavas and ashes. We approach the problems of crust and mantle dynamics from the geophysical and geological points of view. We investigate the physical and chemical structures of the Earth from 3D seismic tomography and from laboratory rock data. The relations between seismic and volcanic activities and the Earth's structure will lead to the understandings of earthquake causes and volcanic eruptions.