Supervolcano blast would blanket U.S. in ash

A new simulation illustrates the explosiveness of the volcano that lurks beneath Yellowstone National Park in Wyoming.

Around 640,000 years ago, the volcano blew its top and coated North America with roughly 330 cubic kilometers of ash. A simulation of the eruption described August 27 in Geochemistry, Geophysics, Geosystems reveals that a similar outburst today would bury Billings, Mont., in more than a meter (about 40 inches) of volcanic glass shards and pulverized rock. Even New York and Atlanta would receive dustings several millimeters thick as winds whisked ash through the darkened atmosphere for days.

Researchers used simulation software called Ash3d that forecasts ash fall by applying global wind patterns to data from historical eruptions. Ash3d churns out results several times faster than previous simulators and is the first program to incorporate the physics of how ash particles clump within a cloud.

While geologists say Yellowstone will likely never erupt again, scientists around the world use Ash3d daily to predict the potential fallout from restless volcanoes — including Bárðarbunga, the Icelandic volcano that began erupting in late August.

Editor’s Note: This article was updated September 24, 2014, to correct the amount of ash produced when the supervolcano erupted 640,000 years ago.