location of 7 of the worlds super volcanoes (photo credit: coolgeography)

Super volcanoes at a first glance don’t appear like normal volcanoes. our stereotypical image of a volcano is a cone-shaped mountain, but a super volcano is the complete opposite. They are large depressions in the ground, that have a magma chamber that is capable for erupting 1000km2 of material. to put this into perspective, a normal volcano has a magma chamber of 1km2 worth of material. In other words super volcanoes are big.  There are about 40 super volcanoes known to the world however most of these are extinct. for example there are two extinct super volcanoes in Britain one in Glencoe in Scotland and another in the peak district.

Super volcano formation

A super volcano forms when the magma cannot escape through the crust like a normal volcano. Therefore it spreads our underneath the crust, putting pressure on the crust creating an uplift bulge as the magma forces the crust above it to rise, into a dome shape. As the pressure increases cracks appear on the surface of the crust and hot gases and ash start to escape from the magma trapped below. finally the crust above the magma chamber breaks away and collapses leaving a depression with steep sides called a caldera. this is the super volcano.

Yellowstone super volcano

Yellowstone is the most famous of all of the super volcanoes in the world and one of the most dangerous as it is located near a populated area in America. It’s caldera is massive: 80km long and 45km wide. It has erupted 3 times so far; once 2.1million years ago, once 1.3 million years ago and once 640,000 years ago. It has been suggested that Yellowstone has a cycle of 600,000 to 700,000 years, which means that an eruption could come any time soon. There have been signs that Yellowstone may erupt in the near future. There have been signs of increased activity inside Yellowstone’s vast magma chamber and the caldera is beginning to bulge up underneath Yellowstone lake. In other places the ground has risen as much as 70cm.

Yellowstone national park (photo credit: national geographic)

So what if Yellowstone does erupt soon? what will happen? In the short-term, large earthquakes would be felt immediately before the eruption and a 15cm layer of ash would cover everything within 1000km and 1 in 3 people affected would die. The sheer force of the eruption  would kill all life within a 50km radius due to the explosions for lava, ash and rock. This would cause severe damage and lead to transport links, electricity supplies and water supplies to be severely damaged or destroyed. The eruption would be a global natural disaster, global temperatures will decrease as ash spreads around the world and blocks out sunlight, these temperatures could drop by as much as 16 degrees C, which could trigger a mini ice age. This would lead to crops failing causing global food shortages and result in further deaths, it has been estimated that the global death toll would reach at least 1 billion. The ash would take around 5 days for it to reach the UK.

This all sounds bad enough, but it has also been suggested that a super volcano could trigger other volcanoes or super volcanoes that are near by to erupt as well. If that happened then the whole planet would be facing a major natural disaster.



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