Supervolcanoes

SOL-Assignment: Volcanism and Human Affairs

Super Volcanoes

1.Definition:

«A supervolcano is a large volcano that has had an eruption of magnitude 8, which is the largest value on the Volcanic Explosivity Index (VEI).»WIKIPEDIA, in Source

1.  Volcanic Explosivity Index (VEI)[pic 1][pic 2]

The Volcanic Explosivity Index, short VEI, is relative, logarithmic scale that compares the explosivity of volcanoes. It is defined by the volume of tephra (liquid pyroclasts) produced during an eruption. Keep in mind, that the VEI 8 isn’t limited, is has an open-end.

        VEI 1                ->        VEI 2

10x stronger

1.  Comparison

A super volcano eruption is about 1000x bigger than the eruption of Mt.St. Helens in 1980. The volume of tephra released from a supervolcano is about 1000km2. The energy released by a supervolcano is 1'000’000x more than the energy released by the atomic bomb in Hiroshima.

2. Structure

Super Volcanoes can occur when a huge amount of magma is being accumulated in the Earth’s mantle, most likely caused by a Hotspot below the mantle. Pressure rises and a magma pool evolves under the mantle. This accumulation will continue as long as the mantle can contain the pressure. If this isn’t the case anymore it results in a massive explosion releasing huge amounts of magma and volcanic ash over several kilometers. Typical for a super volcano eruption is an about 20km high ash cloud with over 1000km2 of tephra released and a VEI of 8.

3. Occurrence:

Super Volcanoes may occur all over the Earth. They are located along plate boundaries or more likely above hotspots.

3.1 Yellowstone Super Volcano:

The Yellowstone Super Volcano is one of the most famous and biggest supervolcanoes on the Earth. It is located in the Yellowstone National Park in the State of Wyoming and is caused by a massive hotspot under the Earth’s mantle. There have been 3 supereruptions:

1. 2.1mio years ago
2. 1.3mio years ago
3. 630'000 years ago

These caused a caldera in the Yellowstone National Park measuring 55 by 72km. Looking at the time passed since the last eruption, we can see a regular pattern. This mean, that we would be due for another supereruption soon. Increase of earthquakes in the Yellowstone Park show an uplift and accumulation of magma below the mantle. Another supereruption would have massive effects on mankind and nature.

4. Effects:

As one can imagine, there would be several effects on mankind and nature if a supervolcano like the Yellowstone one would explode. There are common effects like the magma flow and the ash cloud, but also several more…[pic 3][pic 4]

4.1 Effects on Mankind:

• Panic
• Ash can kill and sicken humans
• Severely disrupt air, road and rail transport
• Crush buildings – 30 cm of dry ash is enough to collapse a roof
• Contaminate water supplies
• Release of supluric acid
• Collapse of the global economy

4.2 Effects on Nature:

• Reduce sunlight -> Climate change (potential drop by 10 degrees)
• Trigger rainfall causing mudslides known as lahars

• Kill crops and other vegetation
• Destroy many species

5. Conclusion:

Super Volcanoes are a huge, massive and interesting threat towards mankind and nature. A supereruption would cause dramatic changes to our day-to-day life.

Source:

1. https://en.m.wikipedia.org/wiki/Supervolcano (14.12.2017)
2. https://en.m.wikipedia.org/wiki/Volcanic_Explosivity_Index (14.12.2017)
3. http://www.bbc.co.uk/sn/tvradio/programmes/supervolcano/article2.shtml (14.12.2017)
4. http://www.vulkane.net/vulkanismus/tephra-pyroklastika.html (14.12.2017)
5. http://www.geography.learnontheinternet.co.uk/topics/whatisasupervolcano.html (14.12.2017)
6. https://www.forbes.com/sites/quora/2017/10/27/when-will-the-yellowstone-supervolcano-erupt/#4b10080c3b36 (14.12.2017)

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