How the World Really Works: The Science Behind How We Got Here and Where We're Going

by Vaclav Smil

Americans should not worry either about supernovas or asteroids, but if they want to scare themselves by thinking about an inevitable natural catastrophe (and one that would emanate from one of the country’s cherished places!) then they should consider another mega-eruption of the Yellowstone supervolcano.[72] Geological evidence shows nine eruptions during the past 15 million years, with the last three known eruptions occurring 2.1 million, 1.3 million, and 640,000 years ago. Of course, the dating of just three events offers no basis for predicting any periodicity, but still a thought intrudes: taking the mean interval of 730,000 between eruptions we would have still 90,000 years of waiting left, but if the first interval was 800,000 years and the second one was 660,000 years then a similar shortening would indicate the next span being some 520,000 years—and a new eruption would be already more than 100,000 years overdue!