Introduction
For as long as the planet has existed, volcano eruptions have been a common feature of geology. The same has posed numerous threats to the world, including loss of life, property destruction, and the environment in general. Super eruptions, in particular, pose a more significant threat. Active volcanoes worldwide have been known to erupt periodically, with massive explosive eruptions much more significant than those seen in the past. Yellowstone, Mount Vesuvius in Campania, Italy, and Popocatepetl in Mexico are among the world's most dangerous volcanoes. Research has shown that in the case that these volcanoes erupt today, they would result to massive loses of life, pollution and poisioning of the earth's atmosphere with ash, gases and other toxins that are far beyond man's activity or global warming in a scale that would be felt for the next over 1000 years. The focus of this paper is the Yellowstone National Park located in Wyoming and Montana and which sits atop a massive reserve of magma that last witnessed an eruption 640,000 years ago but whose eruption scientists have warned off.
Super Eruptions
A super eruption can be described as those eruptions that eject magma of mass over 1015 Kg to the earth's atmosphere. The volume ejected can be greater than 450km3, indicating that the consequences on the immediate human life, property and nature could be detrimental. To increase scope of the definition, however, the term "super eruptions" has been used in the definition of those relatively short-term, explosive events that have a volcanic explosivity index of 8 or above and which produce deposits that exceed 1000km3. A supervolcano such as the one in Yellowstone National Park can therefore be described as a volcano that has produced at least one super eruption in the geological age or period that can be analyzed. Yellowstone falls into the category of super volcanoes due to its immense size and the fact that it is an active volcano (Miller & Wark, 2008). Yellowstone further has a caldera measuring 34 by 45 miles (55 by 72 km). The calderas of super volcanoes are known to be gigantically huge. This is because as they erupt, the existing surface collapses to form an even larger caldera. The huge amounts of materials emitted during eruptions are also a reason (Miller & Wark, 2008)..
Characteristics of Super Volcanoes
As noted, the main distinction of super volcanoes and super eruptions from other volcanoes is the magnitude, which is in the order of 1015 Kilograms in mass. The other distinction is that they are that they cover. At the same time, they are extremely destructive to animal and the environment at large. The appearance of the caldera after the eruption is also distinct: the caldera does not conform to the common shape of conical structure that characterizes most other volcanic eruptions. The super volcano are large calderas with are sub circular in shape and have negative topographic features. This results during the eruptions. As the eruptions happen, the existing surface structures prior to the eruption are collapsed and compressed by the materials to form the resulting caldera (Miller & Wark, 2008)..
Formation and Origins
Super volcanoes are thought to be as a result of either a hotspot or a mantle plume. This implies that the feeder magma comes from deep within the earth surface and not simply crust materials that has recently melted. This is unlike most other volcanoes that have molten earth matter rising back to the surface from a more centralized location. In comparison to others, it can be noted that both Hawaii and Yellowstone Hotposts are a result of hotspot activity in the subsurface. One of the biggest differences that a supervolcano such as Yellowstone has over others such as Hawaii is the large size of the caldera. The magma from both the Hawaii site and Yellowstone has also been said to be different: while the magma in Yellowstone is very thick and pasty, containing massive amounts of gas at high pressure beneath the surface (Miller & Wark, 2008).
Eruption Mechanism
Super eruptions technically contain large amounts of water that causes gas bubbles, highly viscous material. The pressurized water in gaseous form is what drives the explosion. It can be argued that one of the main things that sets the super volcanoes apart from others is simply the enormous amounts of magma that is erupted. A case in point is also the comparison of the volumes of the recent eruptions to that of super eruptions. From the two recent eruptions, Mount St. Helens and Mount Pinatubo have had considerably high impact but they are still lower in magnitude than the Yellowstone super eruptions (Yellowstone National Park, 2017).
Eruption Process and Consequences
Explosive eruptions are mostly caused by disturbances in the structure that leads to the extensive bubble growth. Expansion of magma through the various circumstances that lead to it has been known to increase the pressure of the container which in the case of overpressure can easily exceed the strength of the surrounding rock, leading to it failing. This failure can easily result in magma being injected into the fracture that forms in the surrounding rock. This may potentially reach the surface and erupt. Some of the causes that have been associated with causing the explosions include gas saturation in the magma which leads to crystallization. At the same time, the voids that form in the magma during the movements are quickly filled by fresh magma, forcing the magma out eventually (Yellowstone National Park, 2017).
During the process, the eruptions tear apart the frothy and gas-rich magma, ending up producing fine hot fragments known as pyroclasts. These pyroclasts consist of solidified molten components and crystals. Large explosive eruptions are characterized by large amounts of hot, buoyant gas-containing substances. The mixture of gases that characterizes supereruptions then enters the atmosphere at temperatures that are close to that of the magma within the crust and which is continuously rising (Miller & Wark, 2008). The mixture of gases and pyroclasts then heats the air and rises to as high as 35 km in the sky, spreading out as a massive umbrella cloud that forms in the stratosphere (Lowenstern, & Hurwitz, 2008).
The fragments that form then fall back to the earth surface in either as snow while the remaining hot and highly fluid pyroclastic flows flow on the ground surface at speeds of up to 100 kilometers per hour and can be devastating—they flow covering areas of several thousand square kilometers with the deposits that mainly consist of ash remains (Hotspot volcanoes, 2017).
Occurrence and Monitoring
Super volcano eruptions are clearly one of the most disastrous geological event that can affect the planet. Statistically, super eruptions have been known to occur very infrequently. The last super eruption in the Yellowstone National Park occurred over 600,000 years ago. The average occurrence rate is an average of one eruption in 100,000 years on an analysis of all the eruptions in the world in the most recent geological dating. In the most recent geological age, Yellowstone has had at least three super eruptions. The earliest eruption happened 2.1 million years ago, followed by the one that happened 1.2 million years ago and then the most recent at 640,000 years ago as discussed above. The most recent eruption saw the creation of a sunken giant caldera that is 1,500 square miles (Conners, 2015).
Due to the potential danger that the eruption could possibly cause if it erupted, there has been need to ensure that the place is monitored round the clock. The Yellowstone National Park staff and the Yellowstone Volcano Observatory (YVO) are some of the entities tasked with monitoring the progress of the volcanoes. In addition to the Yellowstone Volcano Observatory, the other entities that monitor the volcano include the United States' Geological Survey (USGS) and the University of Utah. The University of Utah in particular has invested in about 31 seismograph stations across the national park. These tools help record the activities in the crust across the clock. In terms of preparedness, there is little that can be done as the repercussions are more broad and fatal. The fact that they occur fairly less frequently makes it hard to plan. Some of the consequences as mentioned above include destruction of life, infrastructure and virtually everything in the radius given. At the same time, the longtime consequences far supersede global warming as noted by some experts.
References
Conners, D. (2015). What is the Yellowstone supervolcano? | EarthSky.org. Earthsky.org. Retrieved 6 June 2017, from http://earthsky.org/earth/what-do-you-know-about-the-yellowstone-supervolcano
Hotspot volcanoes - Hawaii and Yellowstone Lesson #9 | Volcano World | Oregon State University. (2017). Retrieved from http://volcano.oregonstate.edu/hot-spot-volcanoes-hawaii-and-yellowstone-lesson-9
Lowenstern, J. B., & Hurwitz, S. (2008). Monitoring a supervolcano in repose: Heat and volatile flux at the Yellowstone Caldera. Elements, 4(1), 35-40.
Miller, C. F., & Wark, D. A. (2008). Supervolcanoes and their explosive supereruptions. Elements, 4(1), 11-15.
Yellowstone National Park is a volcano (more specifically, a Supervolcano). (2017). Retrieved from http://www.yellowstonepark.com/things-to-do/yellowstone-supervolcano/
