When I visited Yellowstone two summers ago, the immense “supervolcano” percolating under the national park was a near-constant topic of conversation at the nightly campfire lectures. A 2005 BBC/Discovery drama was the reason why. Inspired by the real existence of the Yellowstone Caldera – which shaped the region through numerous eruptions over the past 17 million years – the sensational disaster yarn imagined what might happen if the huge volcano erupted today, highlighting the fact that the park’s various geysers, fumaroles, and mud pots are signs of continuing volcanic activity.

The last major eruption of the Yellowstone volcano was about 640,000 years ago. There is no indication that it is set to go off again anytime soon, but the