Glossary of Terms

Convection: movement of a fluid’s molecules by advection or diffusion, think of a pot of boiling water.

Core: inner most part of a planet. Crust: outermost layer of a planet.

Earthquake: shaking of the surface of the Earth caused by energy released from fault rupture and sending seismic waves around the Earth.

Hot spot: A plume originating from the core-mantle-boundary remains in a stable location over time, creating a chain of volcanoes as the plate moves over the spot and new material breaks through the surface.

Lithosphere: Rigid outermost shell of a planet. On Earth, this is the crust and part of the upper mantle directly below the crust.

Mantle: The Earth’s internal layer between the crust and the core, made of silicate core.

Mantle Convection: The convection of the Earth’s mantle by advection (movement of molecules) or diffusion (movement of substance from area of high concentration to low concentration). The Earth’s mantle is heated from below by the core and the removal of heat from the system drives convection in the mantle, which in turn drives surface processes (like plate tectonics).

NASA: National Aeronautics and Space Administration, is the space agency in the United States of America.

Plume: A hot, less dense upwelling in the mantle which can be tubular in nature. Project Magellan: A Venus Radar Mapper, a space probe launched by NASA.

Ridge: Area between two divergent plates (plates moving apart from each other) where new lithosphere is created from the upwelling mantle beneath.

Seismic evidence: Seismology data from earthquakes. Waves from earth- quakes help us learn about the composition and structure of a planet.

Seismic tomography: imaging the Earth’s internal structure and charac- teristics using wave measurements from earthquakes to create 3D images of the Earth’s velocity structure.

Subduction zone: A region on Earth with convergent plates (where two plates are moving towards each other) where one plate is subducting (sinking) below another recycling lithosphere into the mantle.

Volcano: rupture on the surface of a planet allowing lava, ash and gases to escape from the planet.