This three-dimensional perspective
view of Long Valley, California
It is thought that one Indonesian super eruption 74,000 years ago was so large it almost destroyed the whole human race. The cause of super eruptions is believed to be a massive magma pool that is created a few miles under the earth's surface.
Previously, it was thought that this process takes 100,000-200,000 years until it is ready to erupt.
But researchers at Nashville's Vanderbilt University suggest a study published in the Public Library of Science ONE journal that in it might only take a few hundred years until it erupts.