What is a Supervolcano?
A volcano is a vent in the crust that occasionally erupts gas, lava, and solidified rock. In explosive eruptions, ash, crystals, and pumice are erupted and this type of eruption and material is called "pyroclastic". Most volcanic eruptions release 1 - 10 cubic kilometers of material, but supervolcanic eruptions are rare events in which at least 1000 cubic kilometers of pyroclastic material or at least 450 kilometers of magma is ejected during one catastrophic eruption! As an idea of how much magma that is....remember that the famous eruption of Mt. St Helens in 1980 resulted in only 0.1 cubic kilometers of magma being erupted and lasted about 9 hours. So a supervolcanic eruptions would be equivalent to approximately 4500 Mt St Helens eruptions happening in 9 hours in an area the size of the city of Los Angeles. When that much material leaves an underground chamber, what remains near the surface collapses to fill the empty volume. The resulting depression at the surface is called a “caldera”, which means “cooking pot” in Spanish. There is a high concentration of these calderas in the Andes Mountains around the border shared by Bolivia, Chile, and Argentina.
Common volcanos such as Láscar and Uturuncu are formed when water is released from oceanic plates in subduction zones. Supervolcanos are also found near subduction zones, or above mid-plate hotspots. 2. Supervolcano
Volcano vs. Supervolcano 1. Volcano
Common volcanos such as Láscar and Uturuncu are formed when water is released from oceanic plates in subduction zones. Supervolcanos are also found near subduction zones, or above mid-plate hotspots.
This cross-section demonstrates how magma is distributed under a caldera. Similar calderas are located on the map above.
3. Example: Cerro Galán
One of the world’s best-exposed supervolcanic calderas in Catamarca, Argentina is shown in this satellite image. The caldera is outlined in red, and the resurgent dome is outlined in orange.
How big is super? Volcano Explosivity Index (VEI) - is a measure of the relative explosiveness of volcanic eruptions.
When will the next eruption occur and how large will it be?
Links http://www.volcano.si.edu/world/list_allnames.htm List of all the volcanoes in the world put together by the Smithsonian http://volcano.oregonstate.edu/ Volcano World hosted by Oregon State University