Ash Fallout Zones from Previous Yellowstone Eruptions Predict a Possible Future

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The Yellowstone super-volcano is located in Yellowstone National Park and covers parts of the states of Wyoming, Idaho, and Montana. The U.S. Congress and President Ulysses S. Grant established the national park in 1872.

Track of the Caldera Over Millions of Years

But caldera of the super-volcano wasn't always where it is today. The hotspot called the Snake River Hotspot that feeds the caldera has tracked across the state of Idaho over millions of years due to plate tectonics.

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Today when we think of Yellowstone National Park we think of geysers and colorful pools of hot water (Image Sources).

The Dark Side of Yellowstone

But Yellowstone has a dark side that it shows approximately every 630,000 years. The dark side of Yellowstone is a super-volcano eruption that covers much of the United States in volcanic ash.

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The current caldera under Yellowstone has been studied and found to be much larger than scientists previously thought.

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Ash from Last Three Eruptions

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Geologists have deduced three separate eruption events from the super-volcano; Huckleberry Ridge eruption 2.1 million years ago, Mesa Falls eruption 1.3 million years ago, and the Lava Creek eruption 630,000 years ago. These eruptions covered much of the western and central United States in ash. The ash track from the Mount St. Helens eruption in 1980 is shown for comparison.

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By studying ash deposits around the region, like the Mesa Falls Tuff deposit shown below, geologists estimate that the maximum thickness of the ash reached up to 660 feet. That is enough to cover many of our modern skyscrapers.

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Scientists estimate that the Lava Creek eruption coated North America with 330 cubic kilometers of ash. Using an Ash3d simulation program researchers applied current global wind patterns to predict the ash distribution across North America from a similar sized eruption.

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Volcanic Winters from Ash Clouds

Geologists at U.C. Santa Barbara studied the volcanic winters induced by the super-volcano eruptions which temporarily blocked out sunlight and cooled the planet. The study was conducted by measuring isotopes in foraminifera shells.
Foraminifera are tiny photosynthetic organisms in the ocean. Foraminifera absorb different ratios of isotopes incorporation into their carbonate shells depending on the temperature of the surrounding ocean water. By precisely measuring the ratio of isotopes the geologists deduced that the eruptions dropped the ocean temperatures by approximately 3 degrees Celsius.

The Past Could Give Us a Glimpse of the Future

It is safe to say the Yellowstone caldera will erupt one day, but the exact timing of such an event is still unknown. Probabalistically, there is a small probability of an eruption yet the impact of such an event will have very large consequences for those in North America and around the globe.