Question: Do you think that it will be the end of the world when a super volcano erupts?

David Pyle answered on 22 Mar 2011:

No – but it would be a challenging time! We can get some clues about what might happen by looking at past eruptions. About 75,000 years ago there was a huge eruption of the volcano Toba, in Indonesia. This erupted about 3000 cubic kilometres of rock, and formed ash deposits more than 10 cm thick across a huge area. In India, the eruption left very thick deposits of ash – but there are a number of places where you can find stone tools formed by the humans who lived there at the time. Since the stone tools don’t look very different just below and just above the ash deposits, the current thinking is that humans did manage to survive this super-eruption.

The next supereruption may not happen for many thousands of years. When it does it will cause devastation to the area close enough to the volcano to be buried under 30 cm or more of volcanic ash; this might be an area of, say, a hundred thousand square kilometers (the size of a whole state in the USA, like Wyoming; or a box about 300 km by 300 km), and an area of over 2000 km by 2000 km would receive significant ash fall (a few centimetres) – but this is still only a fraction of the surface area of the Earth. The whole Earth would feel the effects, though, first due to the very fine ash in the atmosphere (this would only last a few days), and later due to the amounts of sulphur emitted to the atmosphere. This would make the whole planet hazier than it currently is, leading to a cooling of Earth’s surface. At the moment, none of the computer simulations that anyone has done show that even the largest eruption we can imagine would do some as major as starting an ice age. Instead, the Earth would be cold for a few years, but then would bounce back..