Yellowstone National Park is famous for its bison, geysers, and rainbow-coloured hot springs. What’s hidden in plain sight is that the entire park sits inside the crater of one of the largest volcanoes on Earth - a “supervolcano” big enough to change global weather when it erupts.
The crater, or caldera, is about 70 kilometres across. Yellowstone has had three giant eruptions in the past 2.1 million years, the most recent 640,000 years ago. Magma sits just 8 kilometres below the surface, which is why the park bubbles with around 10,000 hot springs and geysers including Old Faithful.
The good news: there are no signs Yellowstone is about to blow. The ground rises and falls a few centimetres regularly as magma shifts, but a full supereruption probably isn’t due for tens of thousands of years.
