Yellowstone Supereruption Would Spew Ash Across North America and Alter Climate

How explosive would a volcanic supereruption at Yellowstone National Park be? It would be pretty devastating. A new study reveals that the Rocky Mountains would be blanketed in meters of age, and millimeters would be deposited as far away as New York City, Los Angeles and Miami.

A supereruption is the largest class of volcanic eruption. It occurs when more than 240 cubic miles of material is ejected into the atmosphere. If this type of supereruption were to occur, in fact, it could shut down electronic communications and air travel across the entire continent. It could also alter the climate.

Currently, a giant underground reservoir of hot and partly molten rock is located beneath the volcano at Yellowstone National Park. This region has been active in the past, and has actually produced three huge eruptions about 2.1 million, 1.3 million and 640,000 years ago. That said, current geological activity doesn't show signs that a massive eruption would occur any time in the near future. Yet scientists were still intrigued about what could occur during a massive eruption.

That's why the researchers turned to computer models. They ran a model that calculated ash distribution for eruptions of all sizes; the model incorporated data on historical wind patterns and other data.

So what did they find? Cities could be covered by a few feet or just a few inches of ash, depending on their location from the eruption. It also seems like the ash doesn't always follow wind patterns.

"In essence, the eruption makes its own winds that can overcome the prevailing westerlies, which normally dominate weather patterns in the United States," said Larry Mastin, lead author of the new paper, in a news release. "This helps explain the distribution from large Yellowstone eruptions of the past, where considerable amounts of ash reached the west coast."

During a large volcanic eruption, the expansion rate of the ash cloud's leading edge could exceed the average ambient wind speed for hours or even days, depending on the length of this eruption. This expansion could drive ash more than 932 miles upwind, producing a bull's eye-like pattern centered on the eruption site.

"These model developments have greatly enhanced our ability to anticipate possible effects from both large and small eruptions, wherever they occur," said Jacob Lowenstern, co-author of the paper.

The findings are published in the journal Geochemistry, Geophysics, Geosystems.