A massive magma reservoir has been discovered 12 to 28 miles beneath the Yellowstone supervolcano, and it is 4.4 times larger than the shallower, long-known magma chamber, according to new research.

In fact, the chamber of hot, molten rock is so vast that it could fill the 1,000-cubic-mile Grand Canyon 11.2 times, whereas the previously known magma chamber would fill the Grand Canyon "only" 2.5 times.

"For the first time, we have imaged the continuous volcanic plumbing system under Yellowstone," first author Hsin-Hua Huang, from the University of Utah, said in a statement. "That includes the upper crustal magma chamber we have seen previously plus a lower crustal magma reservoir that has never been imaged before and that connects the upper chamber to the Yellowstone hotspot plume below."

While most people believe these magma basins are full of molten rock, in actuality the rock is hot, mostly solid and spongelike, with pockets of molten rock within it. Specifically, the upper magma chamber is made up of about nine percent molten rock and the lower magma reservoir is about two percent melt.

In other words, there is about one-quarter of a Grand Canyon worth of molten rock within the much larger volumes of either the magma chamber or the magma reservoir, researchers say.

Previous studies have warned that because the Yellowstone National Park sits atop a vast reserve of molten rock, a super eruption may occur within the next few centuries. And though researchers have said the results would likely not be catastrophic, now that a new massive magma reservoir has been discovered, does that put the region more at risk of an eruption?

The researchers say no, because Yellowstone's plumbing system is no larger than it was before, and therefore no closer to erupting. It's merely that now they have used advanced techniques to make a more complete image of the system.

"It gives us a better understanding the Yellowstone magmatic system. We can now use these new models to better estimate the potential seismic and volcanic hazards," added co-author Fan-Chi Lin.

The plumbing system involves carrying hot and partly molten rock upward from the top of the Yellowstone hotspot plume - about 40 miles beneath the surface - to the magma reservoir and the magma chamber above it. (Scroll to read on...)

Rest assured, the previously known magma chamber hasn't caused a cataclysmic supereruption at Yellowstone since 640,000 years ago. Before that, it had only erupted 2 million and 1.2 million years ago, and that isn't changed by discovery of the underlying magma reservoir that supplies the magma chamber.

"The actual hazard is the same, but now we have a much better understanding of the complete crustal magma system," emphasized study co-author Robert B. Smith, a research professor of geology and geophysics at the University of Utah.

The three supervolcano eruptions at Yellowstone - on the Wyoming-Idaho-Montana border - covered much of North America in volcanic ash, and a supervolcano eruption today would probably do the same. The worst this ash plume would do is reduce traction on roads, short-out electrical transformers and cause respiratory problems, as well as damage buildings, block sewer and water lines, and disrupt of livestock and crop production.

And despite the fact that Yellowstone is among the world's largest supervolcanoes, with frequent earthquakes and Earth's most vigorous continental geothermal system, the annual chance that we may experience a supereruption in the near future is only one in 700,000.

So sleep soundly knowing that North America is not going to get rocked by some earth-shattering supervolcano.

Still, the research team will continue to use seismic imaging data to study the vast magma reservoir located beneath Yellowstone, studying both its shallow crust and deeper structures.

The Yellowstone plumbing system and new magma reservoir discovery are described in more detail in the journal Science.

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