Volcano eruptions are being heard of more frequently these days, but gratefully all those eruptions even with their many casualties and damage are only regular volcanoes which can not achieve the magnitude of destruction that a super volcano can produce. These frequent eruptions should not be too surprising to us since almost 80% of the Earth’s surface both above and below sea level is made up of volcanic origin.
Volcano eruptions are due to the shifts of the tectonic plates and the build up of magma. A super volcano eruption can occur when magma build up rises from a hotspot deep within the Earth to the crust being unable to break through, causing the pressure to build up to extremely volatile proportions. A hotspot is considered a place on the Earth’s surface which is removed from the tectonic plate’s boundaries and has seen volcanic actives in the past. You can find further information on what hot spots are and how they are caused at wikipedia.
Since it will take a lot of pressure to finally break the crust it means immense build up of magma pools which can release its pressure in ejecta greater than 1,000 cubic kilometers. That is 240 cubic miles.
Other places they can form are at continental hotspots like Yellowstone or convergent plate boundaries as is the case of Toba.
The six best known still active super volcanoes are the Yellowstone, Long Valley, and Valles Caldera in the United States; Lake Toba, North Sumatra, Indonesia; Taupo Volcano, North Island, New Zealand; and Aira Caldera, Kagoshima Prefecture, Kyūshū, Japan. A great number really since there are an estimated 40 super volcanoes in all with most of them extinct.
Super volcanoes eruption can cover extremely large amounts of Earth surface with lava and volcanic ash and so trigger extreme changes in the earth atmosphere as happened with the Ice Age leading to mass extinctions of species.
The last recorded massive breakout of a super volcano was 74,000 years ago. This was the super volcano named Toba located in the northern part of Sumatra. It is said that its eruption was 10,000 times larger then Mount St. Helens. Its result was a cool down of the entire Earth by no less then 21degree Fahrenheit.
Scientists have estimated that a super volcano break out happens approximately every 50,000 years, which means we are overdue for out next major erruption. For the last several years now Scientists have kept a close eye on Yellowstone who they have slated to be the location of the next eruption. A scary one Billion life death toll over the entire World has been estimated to be the result of such a break out. With its huge crater surface of over 80 kilometer in length and 45 kilometers wide it can have devistating effects on the weather. An estimated drop of close to 12 degree fahrenheit in the northern hemisphere up to 16 degree fahrenheit in the southern hemisphere. This would wreak major havoc with the agriculture and lead to mass starvations.
If you can not picture the force of explosion this would mean to us imagine roughly 1,000 Hiroshima bombs exploding ever second of the break out and you would get very close.
The reason for the speculation that Yellowstone will be the next one to go is a 74 cm rise since 1923 when measuring first began. This means that there is an extensive build up of magma beneath its surface already.
Should Yellowstone erupt it will literally wipe out everything within a 1000 mile radius of it. The Ash clouds are said to be able to blanket the Earth for up to 10 Years before it will fall again. Those are very scary statistics and we can only hope that we do not see it happen in our lifetime.
Sadly this is not an if a super volcano will erupt but a when. It is all part of a natural cleansing and regeneration that the Earth goes through on a more or less regular base which we can not do anything about. Don’t take any drastic measures yet so, an eruption could be as far off as 10,000 to 1 Million years from now. Just a sneeze in the span of Earth Time but a long time for a human life.
Lake Taupo has been questioned as being a super volcano by some scientists, but it has earned its rank as such surely. It first started erupting as far back as 300,000 years ago. It’s most devastating out break so was about 26,500 years ago which was responsible for the new shape of the caldera. Another outbreak was recorded about 1,800 years past. It is said to have a minor eruption approximately every 1,000 years.
The Oruanui eruption is probably the best known of the two with a volcanic explosive index of 8. Most of New Zealand was affect and had an 18cm ashfall as far as 1000 km away on the Chatham Islands.
You may find many more interesting facts on this subject at some of my research resources:
Wikipedia Super Volcanoes
Other very interesting articles on this fascinating geological subject can be found by these worthy writers.
J.A. McLynne: Super Volcanoes in the United States – Long Valley Caldera
Greg Seltz: New Planet CoRoT-7b, the First Super-Lo
Pena: Nature’s amazing yet devastating Phenomenon – Volcano