Skip to main content
U.S. flag

An official website of the United States government

How far would ash travel if Yellowstone had a large explosive eruption?

Knowledge about past eruptions of Yellowstone combined with mathematical models of volcanic ash dispersion help scientists determine where and how much ashfall will occur in possible future eruptions. During the three caldera-forming eruptions that occurred between 2.1 million and 640,000 years ago, tiny particles of volcanic ash covered much of the western half of North America. That ash was likely a third of a meter deep several hundred kilometers from Yellowstone and several centimeters deep farther away (see this map). Wind carried sulfur aerosol and the lightest ash particles around the planet and likely caused a notable decrease in temperatures around the globe.

Learn more: