12 Facts About Super Volcanoes You Need to Know
Supervolcanoes erupt once every few thousand years. The events are so massive that they affect geological and atmospheric conditions on a global scale-they can even threaten species and induce extinction. Here is what we know about them.
1. What Is A Supervolcano?
The word refers to a volcanic center that has had an eruption of magnitude of 8 on the volcanic Explosivity index [VEI]. This means that the deposits measured for the eruption are greater than 1,000 cubic kilometres [240 cubic miles].
2. How They Are Formed?
When magma in the mantle rises toward the Earth’s crust but is unable to break through, a large pool of trapped magma gradually builds until the crust is unable to withstand the extreme pressure.
3. How Are Volcanic Eruptions Classified?
We measure eruptions using the VEI scale, which slides from 1 to 8. The scale was established as a general measurement of the explosive power of an eruption. The most common criteria is the volume of ejecta (ash, pumice, lava) and column height.
4. How Many VEI 8 Eruptions Have There Been?
Based on analysis of volcanic ejecta and deposits, scientists have been able to identify at least 60 EVI 8 eruptions, though none have occurred recently. The most recent one was 26,000 years ago, while the oldest measured eruption happened 30 million years earlier.
5. What Are Some Examples Of Super Volcanoes?
The best non supervolcano is the Yellowstone Caldera in the United States others include lake toba in Indonesia, the taupo volcanic zone in New Zealand, the pacana caldera in Chile, and the Andes central volcanic zone in Argentina.
6. How Did The Yellowstone Caldera Came About?
Measuring 55 kilometre by 72 kilometre [34 Miles by 45 miles] and located in the northwest corner of Wyoming, the yellowstone caldera was formed during the last of three super eruptions over the past 2.1 million years:
The Huckleberry Ridge Eruption 2.1 million years ago created the Island park caldera and the Huckleberry Ridge Tuff. The Mesa Falls Eruption 1.3 million years ago formed the Henry’s Fork Caldera and the Mesa Falls Tuff. 640,000 years ago, the lava Creek Eruption created the yellowstone caldera and the Lava Creek Tuff.
7. How Was The Yellowstone Caldera Discovered?
Contrary to popular belief, it was not discovered via a photo of Yellowstone taken from space, but through observations and field work in the 60s and 70s by scientist Bob Christiansen of the USGS. He was able to trace out the caldera boundaries by observing the rocks and their distribution. It was Christiansen’s geological map that was used to verify NASA’s Satellite images of the Caldera.
8. Have There Been Eruptions Since Then?
Roughly 80 smaller eruptions of various kinds have occurred in or near the Yellowstone caldera since the lava creek Eruption. Currently, volcanic activity takes place mainly through geothermal vents [including the famous Old Faithful Geyser] and ground swelling from the expanding Magma chamber underneath.
9. Just How Large is The Magma Chamber?
The magma reservoir deep below the Caldera’s surface is 80 kilometre [50 miles] long and 20 kilometre [12 miles] wide, and has 960 cubic miles of underground mass. An estimated 6% to 8% of this is filled with molten rock.
10. Will The Magma Continue to Expand and Release Pressure?
The magma chamber contains gases kept dissolved by the immense pressure beneath it. If that pressure is released by some geological movement, some of the gases will blow out and cause the Magma to expand. That expansion would result in further relief of pressure, causing crust material to blow off the top of the chamber, triggering an anormous gas explosion.
11. So Is Another Yellowstone Super Eruption Imminent?
Scientist don’t think we have anything to worry about in the foreseeable future. They cite that the proportion of melt in the magma chamber is too low to allow another super eruption. The probability is approximately 1 in 730,000 or 0.00014% (Taking the average of the two intervals between the three major passed eruptions), meaning it will likely be thousands of years before another big one.
12. What Would Happen If Yellowstone Did Have a 4th Episode?
Volcanic ash would cover an area of up to 330 kilometres [205 miles]. The presence of an umbrella cloud push the ash 1,500 kilometres and [932 miles] away. A more expensive ash distribution could even cover most of the United States, since such as eruption of this scale would create its own winds. Ashfall would be a few centimetres thick at a minimum, triggering environmental and economic effects across the globe. The earth would certainly see a change in global climate.