All About Volcanoes

A volcano is simply defined as an opening in the earth's surface crust through which molten lava, ash, and gases are ejected.

Volcanoes occur most often on or near crustal plates or boundaries, although certain volcanoes known as hotspot volcanoes can occur virtually anywhere. Today’s existing terrestrial volcanoes are believed to have formed when molten rock or magma welled up in the Earth’s interior pushed its way to the surface causing the volcanoes’ initial eruptions.

Volcanoes all generally fit into one of six different categories: Shield volcanoes, Cinder volcanoes, Stratovolcanoes, Submarine volcanoes, Subglacial volcanoes, and the most powerful volcano of all, the Supervolcano. A Supervolcanic eruption can be catastrophic to entire regions both climatically and geologically. Individual volcanoes are typically described as being either active (currently erupting), dormant (not currently active) or extinct (not expected to ever erupt again).

Some of the most famous volcanic eruptions around the world include the Yellowstone Caldera in Yellowstone National Park, Lake Toba in Sumatra, Indonesia, and the devastating eruption of Mt. St. Helens in southwest Washington State in 1980.

For more volcano information, click on any of the volcano pictures, volcano articles or other interactive volcano features below.