The Yellowstone Caldera, a volcano in Wyoming, has more melted rock than previously thought, but this does not reduce the risk of an eruption.

Volcanoes' explosive lifeblood is magma. Yellowstone, located in northwest Wyoming, has a lot of energy trapped beneath its geyser-filled surface. However, lava combines solid and liquid components, and not every component can erupt.

In a New York Times post, the scientists used a relatively new approach to analyze a 20-year-old seismic data collection to determine how much geological goulash may come through the volcano if it explodes. Their research, released on Thursday in the journal Science, suggests that there is far more molten rock in Yellowstone's higher magma storage than thought previously: 16 percent to 20% of it is liquid, compared to earlier estimates of approximately 10%.

The Yellowstone Caldera is one of the world's biggest volcanoes. It had experienced three cataclysmic eruptions that coated North America in dust over the last 2.1 million years and other minor eruptions when lava poured within the caldera, including recent 70,000 years ago.

Yellowstone's Alterations

Scientists are keeping a tight eye on Yellowstone for any alterations that may indicate an eruption, including deformations or earthquakes. Two massive reservoirs supply magma for eruptions under the volcano, one towards the subsurface and another just a few kilometers underneath the surface. Previously regarded as "huge tanks" of magma, the reservoirs now contain a complex "crystal mush" of melted rock and crystals, according to Ross Maguire of the University of Illinois Urbana-Champaign.

The composition of this mush influences the possibility of the volcano erupting: a larger proportion of molten rock to large crystals increases the likelihood of magma mobilization.

Since seismic waves travel more slowly through molten rock, Maguire, with his colleagues, could determine the fraction of molten rock in the deeper magma reservoir by analyzing seismic data collected surrounding Yellowstone over the last 20 years.

Whereas previous assessments utilized a simplistic model that interpreted the disturbances as linear rays, the investigation used supercomputers to analyze the disturbances in three-dimensional space to provide a full picture of the reservoir.

The Grand Prismatic Spring in Yellowstone National Park
(Photo: Lorcel/Shutterstock)
The Grand Prismatic Spring in Yellowstone National Park. A latest estimate discovers more magma beneath Yellowstone's supervolcano. Geologists said magma does not increase the likelihood of an eruption.

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Threshold Rate for Eruption

They discovered that the reservoir is made up of 16 to 20% melted rock on average, compared to a previous estimate of roughly 9% based on assumptions about the form of voids between solid crystals. This implies that the reservoir holds around 1600 cubic kilometers of molten rock, nearly twice as much as the prior estimate of approximately 900 cubic kilometers, as reported by New Scientist.

Despite the most optimistic estimate, Maguire believes the quantity of molten rock is still much below the 35 to 50% threshold required for an eruption. He claims that Yellowstone may spend a considerable portion of its product lifecycle with some melt without erupting.

According to Kari Cooper of the University of California, Davis, who submitted a commentary on the findings, depending upon how the molten rock is distributed, there may be enough for a modest eruption but not enough for a catastrophic eruption. Cooper describes it as a significant advancement in understanding what lies underneath Yellowstone.

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