What Would Happen if the Yellowstone Supervolcano Actually Erupted?

If the supervolcano underneath Yellowstone National Park ever had another massive eruption, it could spew ash for thousands of miles across the United States, damaging buildings, smothering crops, and shutting down power plants. It’d be a huge disaster.

A super-eruption would be very bad – though also pretty unlikely

But that doesn’t mean we should all start freaking out. The odds of that happening are thankfully pretty low. The Yellowstone supervolcano - thousands of times more powerful than a regular volcano - has only had three truly enormous eruptions in history. One occurred 2.1 million years ago, one 1.3 million years ago, and one 664,000 years ago.

And despite what you sometimes hear in the press, there’s no indication that we’re due for another “super-eruption” anytime soon. In fact, it’s even possible that Yellowstone might never have an eruption that large again.

Even so, the Yellowstone supervolcano remains an endless source of apocalyptic fascination – and it’s not hard to see why. In September 2014, a team of scientists published a paper in Geochemistry, Geophysics, Geosystems exploring what a Yellowstone super-eruption might actually look like.

Among other things, they found the volcano was capable of burying states like Wyoming, Montana, Idaho, and Colorado in three feet of harmful volcanic ash - a mix of splintered rock and glass – and blanket the Midwest. That much ash could kill plants and animals, crush roofs, and short all sorts of electrical equipment:

Ash, ash, everywhere

When I called up one of the study’s co-authors, Jacob Lowenstern of the US Geological Survey, he stressed that the paper was not any sort of prediction of the future. “Even if Yellowstone did erupt again, you probably wouldn’t get that worst-case scenario,” he says. “What’s much, much more common are small eruptions – that’s a point that often gets ignored in the press.” (And even those small eruptions are very rare.)

Lowenstern is the Scientist-In-Charge of the Yellowstone Volcano Observatory in Menlo Park, California. So I talked to him further about what we actually know about the Yellowstone supervolcano, what its eruptions might look like, and why the odds of disaster are low.