Supervolcano occurs when magma from the mantle rises to the crust, but the crust contains all the pressure and doesn’t let the magma break through it, and the magma pool is built where magma continues to store until the crust can’t hold the pressure.
Large igneous provinces are most likely to have such eruptions which result in coverage of a vast area with lava and volcanic ash. These provinces consist of a large number of volcanic materials. This sort of eruption can also trigger a small ice age and can also wipe out some species from earth resulting in their extinction.
“Supervolcano is a massive eruption of a volcano, that has a magnitude of 8 on VEI(Volcanic Explosivity Index), and it is most likely to occur in hotspots and subduction zones.” The term Supervolcano has first originated in the year 1925 AD in a scientific debate by Edwin T. Hodge, where he suggested that a huge volcano named as Mount Multnomah existed in the Oregon state of USA. He further added that the Three Sisters are the remnants of the same volcano.
However, in 1949 AD, another volcanologist named F.M Buyers proved that Mount Multnomah was a supervolcano and it had nothing to do with the formation of any peaks of Three Sisters and that they existed independently. In the 2000s, a television show named Horizon popularised the term Supervolcano again which indicated to eruptions that ejected a heavy volume of volcanic materials.
Though there is no definite explosion size for a supervolcano, there are basically two types of eruption that can be determined as a supervolcano. They are labelled as massive eruption and Large Igneous Province.
Massive Explosive Eruption
Volcanic eruptions are classified by Volcanic Eruption Index which is also termed as VEI. An increase of one on this scale of VEI indicates ten times growth in the volume of volcanic material that is erupted. The volcanoes of magnitude 7 or 8 are known as super-eruptions.
Large Igneous Provinces
Large Igneous Provinces are basically a massive accumulation of igneous rocks, and they are the extensive region of basalts due to flood basalt eruption. They occupy several thousand square kilometres and have volumes on orders of millions of cubic kilometres. They release a large number of gases.
These provinces include Siberian Traps, Iceland, Deccan traps and Ontong Java Plateau.
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Oruanui Eruption: Supervolcano
This volcano took place 26,500 years ago in New Zealand Taupo volcanic zone. The total amount of volcanic material that was ejected is 1,170 cubic kilometres.
This volcanic eruption originated in Lake Toba, North Sumatra in Indonesia. It took place 74,000 years ago. It is reported that this eruption produced 2200-4400 million tons of sulfuric acid. Ejecta spread due to this volcano was 2,800 cubic kilometres.
- La Garita Caldera:
La Garita Caldera eruption originated from San Juan Volcanic zone in Colorado, United States. It occurred 27,800,000 years ago. The ejecta spread because of this volcano was 5,000 cubic kilometres.
All of the volcanic eruptions mentioned above were reported of 8 VEI. At least 60 such volcanoes were found according to incomplete statistics.
Volcanoes of 7 VEI are less colossal as compared, but still, they are massive. The most recent eruptions of this magnitude are Mount Tambora (1815 AD) and Mount Samalus (1257 AD).