WHEN supervolcanoes blow they can cover entire continents with ash. But how this happens has been a puzzle because wind and the initial force of the eruption are not enough to carry the ash over such long distances. Now an examination of prehistoric eruptions has come up with an answer.
Supervolcanoes are classified as volcanoes that spew out more than a trillion tonnes of material when they erupt 鈥� equivalent to 30 Krakatoas. Such volcanoes cannot be studied directly as the most recent was Toba in Sumatra around 71,000 years ago.
So Peter Baines from the University of Melbourne, Australia, and Stephen Sparks from the University of Bristol, UK, used geological records of ash volume and magma chamber size to estimate the energy of past blasts and model the plumes they would have generated. From this they deduced that the Earth鈥檚 rotation fans ash out into a giant spinning cloud up to 6000 kilometres wide within one day. 鈥淚t is a bit like a hurricane, but on a much larger scale,鈥� Sparks says.
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Unfortunately the findings don鈥檛 offer a solution for surviving a future eruption, such as if the supervolcano underneath Yellowstone National Park in the US were to blow. 鈥淚鈥檓 not sure what we could do, except stay underground,鈥� says Sparks.
