The study of the planet Earth – the materials it is made of, the processes that act on those materials, the products formed, and the history of the planet and its life forms since its origin.

Geologic time scale
A chronological sequence of geologic events usually presented in the form of a chart showing names of various rock layers and indicating the estimated duration of each geologic unit.

The study of the character and origin of landforms e.g. mountains, valleys etc.

A branch of earth science that uses physical measurements and mathematical models to explore and analyze the structure and dynamics of the Earth’s surface and crust.

Geothermal activity
Activity related to heat generated by the interior of the Earth. Typical features are hot springs, geysers, fumaroles and bubbling mud pools

Geothermal system
A concentrated zone of geothermal activity. Geothermal systems form when rainwater seeps into the ground where it is heated by hot rock. The hot water becomes buoyant, and rises back to the surface along cracks. In some places the water is heated so much that it rises as steam. Geothermal systems consist of a heat source, permeable rock and water.

Geothermal Energy
Energy derived from the internal heat of the earth.

Geothermal Power
Power generated by using the heat energy of the earth.

A sunken area (depression) between two roughly parallel faults formed as a result of extension, or pulling, of the crust.

Ground failure
A general term that refers to any consequence of ground shaking that affects the stability of the ground.

Ground motion
Ground motion is the movement of the earth’s surface from earthquakes or explosions.

Global Positioning System. GPS is a satellite-based navigation system consisting of three segments: space, ground, and user.

Gutenberg discontinuity
Discontinuity in seismic velocity that marks the boundary between the core and the mantle; named after seismologist Beno Gutenberg.