A volcanic ‘super eruption’ could devastate our planet - covering huge areas in ash, changing the climate, and even driving species to extinction.
But we would have little warning of such a devastating event, according to Vanderbilt University researchers.
Only in the last year before an impending super-eruption would signs be felt on the surface, intensifying before the final explosion.
Researchers from Vanderbilt and Chicago universities analysed quartz crystals in pumice taken from the Bishop Tuff in eastern California, which is the site of the super-eruption that formed the Long Valley Caldera 760,000 years ago.
Guilherme Guilda said, ‘The evolution of a giant, super-eruption-feeding magma body is characterized by events taking place at a variety of time scales.
‘Now we have shown that the onset of the process of decompression, which releases the gas bubbles that power the eruption, starts less than a year before eruption.’
Very large eruptions - including super-eruptions - have taken place in a number of places worldwide in the recent geological past.
The Taupo Volcanic Zone in New Zealand was the site of the most recent super-eruption - the Oruanui eruption at 26,500 years - and it includes deposits from more than a dozen very large eruptions that took place in the last couple of million years.
Campi Flegrei in Italy produced a very large eruption 40,000 years ago. Indonesia was the site of the Toba super-eruption in Sumatra 75,000 years ago and the Tambora eruption in 1815.
In the United States, Yellowstone has experienced three super-eruptions over the last two million years. In light of this evidence, it seems inevitable that another super-eruption will strike the Earth in the future.