In south-west Colorado, there is a vast canyon approximately 100km wide and one kilometre deep. It serves as the legacy of one of the most explosive single events in the planet’s history. La Garita Caldera was formed by an eruption nearly 28 million years ago, which expelled 5,000 cubic kilometres of molten rock.

Fortunately for us, the tectonic plates in the area have since rearranged themselves, so a repeat event is impossible. But approximately 75,000 years ago in Indonesia, an eruption of similar scale occurred, and the supervolcano responsible remains active.

Situated in the midst of a mountain range in northern Sumatra, the tranquillity and natural beauty of Lake Toba makes it a popular tourist location. But this lake is actually an enormous caldera, a footprint of the most extreme climatic event in human history.