is a mountain that has lava come from a magma chamber under the ground.
Types of Volcanoes:
- Shield Volcano: Formed by fluid low-silica mafic lava. (E.g. Mauna Kea in Hawaii).
- Composite Volcano: AKA Strato Volcanoes. Unlike shield volcanoes, these have a steep profile and periodic eruptions. (E.g. Mount Fuji in Japan and Vesuvius).
- Caldera Volcano: A caldera is a basin-like feature formed by collapse of land after a volcanic eruption. It is most dangerous category of volcanoes. They have coolest lava with temperature ranging from 650 to 800o C.
Based on pattern of eruption:
- Active: Currently erupting or it has erupted in the last 10,000 years. (E.g. Mount St. Helens in US).
- Dormant: Sleeping but could awaken in the future. (E.g. Mount Rainier in US).
- Extinct: Has not erupted in the past 10,000 years. (E.g. Edinburgh Castle in Scotland).
# Key Points
- Volcanoes are formed by the movement of tectonic plates.
- Most volcanoes have a volcanic crater at the top. When a volcano is active, materials (lava, steam, gaseous sulfur compounds, ash and broken rock pieces) come out of it.
- When there is enough pressure, the volcano erupts.
- Volcanoes are found on planets other than Earth (E.g. Olympus Mons on Mars).
- The world's biggest volcano is named Mauna Loa in Hawaii.