A catastrophic supervolcano eruption – one which would result in a global death toll – is much more likely than previously believed, a new study suggests.
Around 20 such volcanoes ,which scientists had believed to be semi-dormant, may still pose a present risk, the research says.
Until now, it had been widely thought that the likelihood of a blow-out was dependent on the presence of liquid magma under a volcano.
But the new research – coordinated by Oregan State University, in the US, with scientists from across the world – found evidence that “eruptions can occur even if no liquid magma is found”.
If right, it means that various supervolcanoes previously thought to hold only potential future danger could still be highly hazardous right now to humankind.
“The concept of what is ‘eruptible’ needs to be re-evaluated,” said Associate Professor Martin Danisik from Curtin University in Australia, one of the lead authors of the research published this week in the Communications Earth & Environment journal.
The team came to the conclusion after investigating what happened after the Lake Toba super-eruption some 75,000 years ago in what is today Indonesia.
The event itself is said to have caused a years-long global winter which shrunk the then human population to as few as 3,000 people.
But it is the fact that magma appears to have continued oozing for up to 13,000 years afterwards that has especially interested scientists – because it may suggest that eruptions can occur without the presence of liquid magma in the first place.
Professor Danisik said: “Super-eruptions are among the most catastrophic events in Earth’s history, venting tremendous amounts of magma almost instantaneously. They can impact global climate to the point of tipping the earth into a ‘volcanic winter’, which is an abnormally cold period that may result in widespread famine and population disruption.
“Learning how supervolcanoes work is important for understanding the future threat of an inevitable super-eruption.”
He added: “While a super-eruption can be regionally and globally impactful and recovery may take decades or even centuries, our results show the hazard is not over with the super-eruption and the threat of further hazards exists for many thousands of years after.
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“Learning when and how eruptible magma accumulates, and in what state the magma is in before and after such eruptions, is critical for understanding super-volcanoes.”