Scientists have made a breakthrough in their efforts to understand what causes so-called supervolcanoes to erupt.
Supervolcanoes are capable of eruptions thousands of times larger than normal outpourings.
It was thought that an external trigger, such as an earthquake, was needed to bring about a giant blast.
But tests at the European Synchrotron Radiation Facility in Grenoble show the sheer volume of liquid magma is enough to cause a catastrophic super-eruption.
Details of the research by a Swiss team appear in Nature Geoscience. .
Simulating the intense heat and pressure inside these “sleeping giants” could help predict a future disaster.
Lead author Wim Malfait, of ETH Zurich, said: “We knew the clock was ticking but we didn’t know how fast: what would it take to trigger a super-eruption?
“Now we know you don’t need any extra factor – a supervolcano can erupt due to its enormous size alone.
“Once you get enough melt, you can start an eruption just like that.”
There are about 20 known supervolcanoes on Earth – including Lake Toba in Indonesia, Lake Taupo in New Zealand, and the somewhat smaller Phlegraean Fields near Naples, Italy.
Super-eruptions occur rarely – only once every 100,000 years on average. But when they do occur, they have a devastating impact on Earth’s climate and ecology.
When a supervolcano erupted 600,000 years ago in Wyoming, in what today is Yellowstone National Park, it ejected more than 1,000 cubic km of ash and lava into the atmosphere – enough to bury a large city to a depth of a few kilometres.
This ejection was 100 times bigger than Mt Pinatubo in the Philippines in 1992 and dwarfs even historic eruptions like Krakatoa (1883).
“This is something that, as a species, we will eventually have to deal with. It will happen in future,” said Dr Malfait.
“You could compare it to an asteroid impact – the risk at any given time is small, but when it happens the consequences will be catastrophic.”
BBC has the full article