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Geography

Volcanoes and volcanic eruptions

Supervolcanoes

A supervolcano is a volcano on a massive scale. It is different from a volcano because:

  • it erupts at least 1,000 km3 of material (a large volcano erupts around 1 km3)
  • it forms a depression, called a caldera [caldera: A cauldron / depression shaped tectonic feature usually formed from the collapse of a magma chamber. ] (a volcano forms a cone shape)
  • a supervolcano often has a ridge of higher land around it
  • a supervolcano erupts less frequently - eruptions are hundreds of thousands of years apart

The stages in the creation of a supervolcano caldera

The stages in the creation of a supervolcano caldera

Magma cannot escape to the surface and collects under the lower crust.

Yellowstone

A hydrothermal feature at Yellowstone Park, Texas, USA

A hydrothermal feature at Yellowstone

Yellowstone is one example of a supervolcano. Three huge eruptions have happened in the last 3 million years. the last eruption was 630,000 years ago, and was 1,000 times bigger than the Mount St Helens eruption in 1980.

The large volume of material from the last Yellowstone eruption caused the ground to collapse, creating a depression called a caldera [caldera: A cauldron / depression shaped tectonic feature usually formed from the collapse of a magma chamber. ]. The caldera is 55 km by 80 km wide. The next eruption is predicted to have catastrophic worldwide effects.

The supervolcano at Yellowstone is formed because of a volcanic hotspot [hotspot: An area of the Earth's crust where an unusually high amount of heat flow is causing volcanic activity. ].

Every year millions of visitors come to see the related features, such as geysers [geyser: A spring of water which has been heated geothermally which erupts intermittently. ] and hot springs. Old Faithful is one example of a geyser.

Back to Natural hazards index

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