Vast magma reservoir found hiding beneath Yellowstone park

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The supervolcano below Yellowstone just got bigger. Under the national park in Wyoming is a chamber holding enough magma to fill the Grand Canyon 11 times over.

We knew there was magma under the surface, in a 10,000-cubic-kilometre chamber. Now a second chamber has been discovered, 20 to 50 kilometres down, with a capacity of 46,000 km³. Together, the two form the largest known magma reservoir in the world, says Fan-Chi Lin of the University of Utah in Salt Lake City.

Previous studies failed to find the chamber because the seismic waves used to visualise deep areas were distorted by rock closer to the surface. Lin’s team got round this by combining readings from shallow and deep waves (Science, doi.org/32r).

The discovery helps to solve two long-running puzzles: how the smaller chamber could produce the 45 kilotonnes of carbon dioxide discharged daily from Yellowstone’s volcanic system, and also how molten material from the mantle, around 60 kilometres down, could travel so far upwards. “We have a much better understanding of how the entire magmatic system works, from the mantle to the surface,” says Lin.

Despite the quantity of magma, the risk of the supervolcano erupting remains very low. Lin says the team’s findings can be applied to other volcanic systems around the world to help predict volcanic activity.

This article appeared in print under the headline “Giant magma chamber found under Yellowstone volcano”