Massive Blasting Power!
According to the U.S. Geological Survey (2013), "Super Volcano" is the word to describe a volcano that can erupt at a magnitude of 8 on the Volcano Explosivity Index. Super volcanoes are huge when comparing their size to an eruption of a normal volcano. The site of these kinds of volcanoes are usually sunken areas, called calderas, that formed when the earth collapsed after previous eruptions. Mankind has never witnessed such a geological phenomenon of this magnitude (Sealy, 2012). Also known as “ultraplinian”, super volcanoes can blast more than 1,000 cubic kilometers (240 cubic miles) of magma (Breining, 2007). The diagram on the left shows of the volume of explosion. The huge circle of red represents the massive magnitude of explosivity that will occur when the volcano within Yellowstone erupts in the undetermined future.
Explosive Activity!
The word "volcano" comes from the name "Vulcan", the Roman god of fire (Simon, 2002). A volcano is not always in the form of a mountain. Quite simply, a volcano is any hole in the Earth's surface through which lava can flow (Van Rose, 1992). A volcano contains three basic elements: magma chamber, conduit and vent (Rosi et al., 1999). Inside the Earth’s crust, about two miles beneath the structure of the volcano, is the magma chamber. Magma is hot, molten rock that can reach temperature well over a thousand degrees Fahrenheit (Van Rose, 1992). When the magma reaches enough pressure to burst through the rocks overhead, the magma will travel through the conduit to reach the surface and erupt through the vent (Rosi et al., 1999). Once the magma erupts onto the surface, it is called lava (Rosi et al, 1999). It can have effusive or explosive activity or a combination of both. Effusive consists in the overflowing of degassed magma from a volcano vent or crater that forms a lava flow. Usually, lava flows slowly (Simon, 2002). Explosive activity is the complete destruction of the magma chamber which discharges fragments of magma into the atmosphere at a high temperature and at high speed (Rosi et al., 1999). Yellowstone will probably exhibit a combination of explosive and effusive activity (Breining, 2007; NPS, 2013).
Violent!
A plinian eruption is produced by magma that is rich in gas which causes the volcano to erupt violently (USGS, 2013). Once the magma is expelled into the air it becomes fragmented. These fragments cool and form pyroclasts. Pyroclasts consist of pumice, cinders and ash particles. The size of this rocky material can vary from fine dust to chunks of rocks the size of houses (Green, 2009). The eruption volume varies between 22 million and 22 billion pounds per second and can cover an area of several cubic miles that rises high into the atmosphere creating an umbrella-shaped cloud. After expanding hundreds of miles, the cloud collapses due to gravity. The cloud mixture of pumice, rock fragments, sandy particles and gas begins to fall to the ground. This avalanche of debris, called a pyroflow, spreads around the volcano, destroying everything (Rosi et al.,1999).