The odds that the Yellowstone supervolcano will erupt are roughly the same as those that the National Weather Service estimates you’ll get struck by lightning in your lifetime: 1 in 10,000. She last blew her top 640,000 years ago. The two times before that occurred roughly 1.3 million and 2.1 million years ago.
So what happens if the “what if” really occurs? Well, based on the past three eruptions of the Yellowstone hotspot, the party starts with an eruption of more than 1,000 cubic kilometers of magma. Jacob Lowenstern, scientist-in-charge at the Yellowstone Volcano Observatory, notes that an eruption of that size will cover most of North America with an ash blanket of varying thickness. Countless lives will be saved if the states surrounding Wyoming have a chance to evacuate, thereby avoiding the heaviest downpour of ash.
It’s the aftermath, however, that will cause the greatest loss of life. The ash-filled air will make breathing difficult for the days following the eruption. The ash-covered vegetation will be smothered. And the ash-polluted water supplies will become poisonous. "A lot of people would perish," Stephen Self, director of the Volcano Dynamics Group at the Open University in the U.K. told the website “Life’s Little Mysteries.”
On the bright side, scientists have concluded that the supereruption won’t cause a mass extinction. "The last time Yellowstone erupted, no extinctions took place," Michael Rampino, a biologist and geologist at New York University, told LLM. "Supereruptions are not extinction-level events," but he clarified that they’re not exactly a boon to civilization.
As a girl who both knows someone who was struck by lightning (odds of knowing a victim of this kind are 1 in 1,000, says the NWS) and lives in a state bordering Wyoming, this freaks me out. At least I don’t have asthma.