A supervolcano is a volcano that can make a volcanic eruption where the things being thrown out of the volcano have a volume bigger than 1,000 km³ (240 cu mi), which is a Volcanic Explosivity Index (VEI) of 8. If the definition is expanded, supervolcanoes also include volcanoes that have volcanic eruptions with a volume bigger than 100 km³ (24 cu mi), which is a Volcanic Explosivity Index (VEI) of 7. This is thousands of times bigger than most volcanic eruptions which happened a long time. Supervolcanoes can occur when magma in the Earth rises into the crust from a hotspot, but can not break through the crust. More and more pressure builds up in a large and growing magma pool until the crust can no longer take the pressure.