A 'supervolcano' eruption is the most catastrophic natural disaster that can hit our planet, short of an asteroid impact - and now scientists believe they may build up a deadly head of steam far faster than we thought.
Instead of the process taking hundreds of thousands of years, it could take just hundreds.
The news could be bad for the US, where a supervolcano is said to be simmering beneath Yellowstone National Park. If it erupted, two thirds of the country could be rendered uninhabitable.
* * *
The new study was based on analysis of a super-eruption that occurred in eastern California 760,000 years ago.As I've noted before, we don't need a super-volcano to cause problems, just an eruption big enough to lower global temperatures by a degree or two for a year or two.
Several independent lines of evidence indicated that the magma pool erupted within a few thousand years, perhaps within a few hundred years, covering half the North American continent with smouldering ash.
The scientists based their estimate on quartz crystallisation rates. Previous studies have relied on the growth of zircon crystals, which is said to be a less accurate method.
The research is published in the online journal Public Library of Science ONE.
Lead scientist Dr Guilherme Gualda, from Vanderbilt University in Nashville, Tennessee, said: ‘Our study suggests that when these exceptionally large magma pools form they are ephemeral and cannot exist very long without erupting.
‘The fact that the process of magma body formation occurs in historical time, instead of geological time, completely changes the nature of the problem.’
He said regions such as Yellowstone should be monitored regularly to provide advance warning of a catastrophic super-eruption.