According to an article published by United States Geological Survey scientist Larry Mastin in the latest edition of Geochemistry, Geophysics, Geosystems, an eruption of the supervolcano beneath Yellowstone National Park would blanket much of the United States in a meter of ash.
Mastin and his colleagues used computer modeling to determine the effects of the kind of ash cloud — known as an “umbrella” — the supervolcano would produce. A supereruption would eject 240 cubic miles of material into the atmosphere, which would not only shut down electronic communication and render air travel impossible, it would immediately and dramatically alter climate across the continent.
The supervolcano beneath Yellowstone has produced eruptions of this scale at least three times — once 2.1 million year ago, once 1.3 million, and most recently, 640,00 years ago. Mastin and his team used data on ash distribution from the most recent eruption to calculate the thickness of the ash fall from another potential supereruption, and found that cities close to the supervolcano would be buried beneath more than a meter of ash.
The “umbrella” ash cloud would deposit ash as far away as New York and Los Angeles, but the damage to the central region of the country would make it difficult, if not impossible, for the two coasts to have any meaningful communication with each other.
Even the small accumulation of ash on the East and West Coast would create massive problems for the population. Traction on roads would be significantly decreased, leading to more automobile accidents; electrical transformers would be shorted-out; sewer and water lines would be blocked; crops would be ruined; and individuals with respiratory problems would find it difficult, if not impossible, to breathe.
Such a cloud would spread across the country in a bull’s eye pattern, because the force of the ejection and the composition of the ejected material would make the cloud more powerful than the prevailing winds.
“In essence, the eruption makes its own winds that can overcome the prevailing westerlies, which normally dominate weather patterns in the United States,” Mastin said. “This helps explain the distribution from large Yellowstone eruptions of the past, where considerable amounts of ash reached the West Coast.”
[“Grand prismatic mineral deposit at Yellowstone National Park” via ynp on Flickr, Creative Commons license]