Scientists have learned that massive caldera volcanoes, like the one stewing beneath Yellowstone, are ruled by geological processes far different than the ones governing conventional volcanoes. These massive reservoirs of magma can explode spontaneously — an important piece of insight that can help us predict a future disaster.
Super-eruptions are extremely rare, occurring once every 100,000 years or so. Disturbingly, these cataclysmic geological events aren't archaic phenomena; we know of at least 20 supervolcanoes on Earth, including Yellowstone, Lake Toba in Indonesia, Lake Taupo in New Zealand, and the Phlegraean Fields in Italy. Scientists say it'll only be a matter of time before the next Big One — an event that could eject upwards of 1,000 cubic kilometers of ash into the sky.