The Earths interior

The effects of geodynamic processes on the Earth's surface give clues about the structure of the Earth's interior.
Schematic cross-section through Earth under the North Atlantic Ocean, illustrating the connection between plate motions and the underlying lithosphere and mantle.

Evidence from earthquake-generated seismic waves shows that Earth's interior has a layered structure, with a thin outer crust overlying a viscous mantle. Further below, a molten outer core surrounds a solid inner core. The crust and the uppermost part of the mantle are together known as the lithosphere. This lithosphere is stronger than the underlying mantle, but both deform. Convection in the viscous mantle is driven by heat from the decay of radiogenic elements and heat left over from Earth’s formation, and this convection drives motions of the lithosphere's tectonic plates. In turn, subduction of lithosphere into the mantle and seafloor spreading at mid-ocean ridges drives mantle flow.

Through the slowly convecting mantle, hot, buoyant material can rise upwards from great depths and break through to Earth’s surface, for example, in areas where the crust has thinned due to extension processes. Such hotspots can cause large lava outpourings, such as the North Atlantic Igneous Province, the Deccan Traps in India or the Siberian Traps.

Researchers at NGU study geodynamic processes using a range of techniques: dating techniques provide time constraints on igneous episodes, numerical models of subduction and extension processes help understand the connections between the Earth's interior and the surface, seismic interpretations highlight the architecture of continental break-up, and field observations constrain collision processes and fault kinematics.