A volcano on Hanon IV
A volcano is an opening in a planet's crust, often formed into a mountain, from which molten lava and gases are ejected.
The study of volcanoes is volcanology.
Volcanoes on Penthara IV were activated when subterranean pockets of carbon dioxide were opened by a phaser drill. The volcanoes started to erupt and produced large plumes of volcanic dust threatening to bring another ice age on the planet. (TNG: "A Matter of Time")
Noted volcanoes
Additional references
- VOY: "Basics, Part II"
- ENT: "Dawn"