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View of the 'Grand Prismatic' hot spring  in the Yellowstone National Park, Wyoming.

The 'Grand Prismatic' hot spring in the Yellowstone National Park, home of a massive underground supervolcano.

PHOTOGRAPH BY MARK RALSTON, AFP/GETTY IMAGES

Ker Than

for National Geographic

Published December 18, 2013

The magma reservoir lurking beneath a dormant supervolcano in Yellowstone National Park far exceeds past estimates of its size, a new analysis shows. (See also "Yellowstone Supervolcano Discovery—Where Will It Erupt?")

"We found it to be about two-and-a-half times larger than we thought," said analysis team scientist James Farrell of the University of Utah in Salt Lake City. "That's not to say it's getting any bigger. It's just that our ability to see it is getting better."

The size finding, presented at the American Geophysical Union fall meeting in San Francisco last Thursday, has big implications for the extent of the volcano's impact when it next erupts. (See "When Yellowstone Explodes.")

The supervolcano underneath the national park last erupted on a massive scale some 640,000 years ago, according to the U.S. Geological Survey (USGS). It is a potential supervolcano, capable of spewing more than 240 cubic miles (1,000 cubic kilometers) of magma across Montana, Idaho, and Wyoming, with global climate effects.

"We believe it will erupt again someday, but we have no idea when," Farrell said.

More Magma Measured

In the new analysis, Farrell and his team calculated the size of the volcano's magma reservoir by analyzing earthquake measurement data collected from 1984 to 2011 from about 40 seismometers installed around Yellowstone.

Yellowstone National Park is located in a very seismically active region and experiences between 1,500 to 2,000 earthquakes a year. Most of the temblors are too small to be felt by humans, but occasionally "you will have a large earthquake like the magnitude 7.3 one that we saw in 1959," Farrell said.

The team used software to calculate how long it takes for the seismic waves to travel from the epicenter of an earthquake to the surface seismometers. They next analyzed the data to find regions where the seismic waves appeared to slow down, which is a sign that the waves were traveling through magma.

"Seismic waves travel slower through molten material," Farrell said.

The team used that information to create a map of the underground magma reservoir beneath Yellowstone. Farrell likened his team's technique to the medical scanners doctors use to image inside the human body. "It's the exact same technique. It's just that we use seismic waves, and we do it on a much bigger scale," he said.

The team's map revealed that Yellowstone's magma reservoir is not arranged vertically, as once thought, but rather it is tilted in a northwest to southeast direction. It's also much bigger than previously thought, measuring about 55 miles by 20 miles (90 by 30 kilometers) on each side and about 6 miles (10 kilometers) deep.

The new size estimate means the current magma reservoir is roughly equal to what it was when the supervolcano last erupted, about 640,000 years ago.

"What we're seeing now agrees with the geologic data that we have about past eruptions," Farrell said. "And that means there's the potential for the same type of eruption that we've seen in the past."

Scientists think that after each eruption, the magma reservoir is emptied, and it takes a long time for it to refill again.

Global Catastrophe

Scientists predict that when the Yellowstone supervolcano does erupt, it will have global consequences. Large amounts of ash and pulverized rock from the eruption will get lofted into the atmosphere and then fall back slowly to Earth.

"You'll get ashfall as far away as the Great Plains, and even farther east," Farrell said.

Furthermore, volcanic material and gases that linger in the atmosphere will block sunlight, resulting in a global temperature decrease.

There will be nothing humans can do to prevent the eruption from happening, Farrell said, but at least with the instruments in place there should be ample warning before the volcano erupts. The Yellowstone Volcano Observatory partnership of state, federal, and academic experts regularly monitors the volcano.

"I think we'll have anywhere from weeks to months of warning that magma is moving up into the shallow crust and [that] something is going on," Farrell said.

As catastrophic as an eruption of the Yellowstone supervolcano would be, Farrell said it's not an imminent threat, nor the one people should be focusing on. The USGS puts the annual odds of a super-eruption at 1 in 730,00.

"The most likely hazard in Yellowstone is from large earthquakes," he said. "A lot of people say that the Yellowstone volcano is overdue to erupt, but there's no evidence that it is overdue. We can't say when the next eruption is going to happen."

Follow Ker Than on Twitter.

68 comments
Kali Black
Kali Black

No mention of the impact of fracking nearby and in surrounding states? 

Ken Graham
Ken Graham

Instead of can not be fixed, should say has not been fixed. Use geothermal piping to run powerplants to remove heat and increase cap thickness and strength. Build for 1000 years if needed, Electricity to power Continent.

Give the endangered species another 700,000 years , they get 0 if it erupts and US and Canada will be gone with the resulting ice age as well.

This is the most important solar project on earth, just use those Super Computers to model it so we don't become the next big bang.

Ken Graham
Ken Graham

Why is it not able to be stopped?

The only issue is it has not been done before.

The cap if cooled should retain more strength and perhaps even thicken. This may be paid for in electricity generated by geothermal power plants, inject water in tubes that convert the water to steam and drive turbines. Consider horizontal trenching if vertical too dangerous.

Continue building for as long as it takes to see a reduction in the Chamber,1000 years if We have the time, I think the lake raising indicates we are in a race. Power the continent.

Model with super computers to do it right, start now.

Kerry McEvoy
Kerry McEvoy

o ye of little faith sure it will blow scientist to not know when and how much. Since the beginning of time men have predicted the end is now. Sorry God is the only one who can and he is not ready for your end of days theories.

F. Manzat
F. Manzat

The people living around Yellowstone are in for a big shock when that thing goes off.

Lukas Armstrong
Lukas Armstrong

Hey man, i'm ready for the apocalypse. I'm ready to go renegade

william wong
william wong

Can somebody out there quickly create a giant vaccuum pump

to pump out the lava , so if there is no more lava , there will be no

more supervolcano eruptions , we all have peace .

MICHAEL LETHER
MICHAEL LETHER

What mechanism causes it?  Could it be an internal wobble or something else? Mars here we come!

Mark Lord
Mark Lord

It went off.  Then 800,000 years later it went off again.  Then 660,000 years later it went off again.  Now it is 640,000 years since the last time it went off.  It's certainly possible to suspect it is already in the window for the next (fairly inevitable) eruption.  


I seem to recall hearing about herds of buffalo as far east as Kansas City that were suffocated by the ash last time it went off.


On the other hand, if it can just wait a century or two I'm fairly sure levels of technology and science that today seem too incredible to discuss will be commonplace and probably quite capable of greatly mitigating even a disaster of this magnitude.


If it can't hold off -- well, we are still wondering why we haven't encountered or seen any signs of extraterrestrial life.  It's not that this would kill us off.  The three previous eruptions failed to do that with our considerably less capable ancestors, but it would certainly damage what we call civilization, perhaps even collapsing it.


The universe is a dangerous place.  Maybe we've just had a charmed existence to get even this far.


For those who say this is what we deserve -- they're entitled to their opinions, of course, but I find it difficult to believe there is, or has been, too little human suffering.  It's also more than a little creepy that there are people that would feel this way.

Chloe Rodriguez
Chloe Rodriguez

You know Google+ is succeding when an article has more +1s than Likes and Twits.

Anlia Stewart Bolinger
Anlia Stewart Bolinger

We as humans have a good run, and if we are wiped out so be it. We do not deserve this planet after the way we have treated it. Live each day to it's fullest and do not dwell on what we can not change. Nature is awsome and I would pull up a front row seat to see this, hey I live in northern Colorado so i kind of already have a front row seat. The earth is billions of years old and has and forever will cycle itself!

Daniel GU
Daniel GU

great danger beneath graceful appearance

jeremy harrower
jeremy harrower

That could and should bring my heating bills down. :-) 


J Parker
J Parker

So, what do we do exactly when we get this warning? Kiss our loved ones goodbye? In Seattle, they're not giving us any training on this. ;-)

calene Shirley
calene Shirley

pretty interesting. however, the earth is not that old.

Jose Gomez
Jose Gomez

I'M MORE AFRAID, CONCERN ABOUT WORLD WAR III.

ANYONE KNOW THE ODDS?

Brian Crawford
Brian Crawford

I think what we can expect is for the experts to be wrong about when it will happen and what will occur when it does.  The Russian meteor 2012DA14 over Chebelinsk was completely unobserved until it hit the atmosphere.  Most catastrophes tend to occur without warning.  What the article doesn't say is the physical impact a Yellowstone eruption would have for the rest of the U.S., east and west of the eruption.  Will Easterners hear the eruption if they're outside?  How much of the debris will land in the U.S. and will it be dangerous?  Questions that will only be answered during the eruption I suppose.

Sara Grover
Sara Grover

Oh no doom's day preppers! Better start hoarding more guns and food!

Bill Sr. Lawler
Bill Sr. Lawler

@Ken Graham  

Ken, your idea on that works, but only if you don't tap into a volcano that's already building pressure, but one that just blew up, Then you coud theoretically keep the pressure reduced. But in oil drilling, if you start to go into an existing high-pressure field, you have to have 'blow-out' preventers, which close the whole on an oil well so it doesn't get away from them. There isn't any technology I ever heard of that can choke off a supervolcano. It's enormously hard just to do that to regular wells because of pressure flucutations and internal geographical changes that occur underground. We got to the table a bit late on this one to go vampire on it, but it would be the end-all on power, that's for sure.

Bill Sr. Lawler
Bill Sr. Lawler

@Ken Graham  

Pressure is a funny thing when you focus it in high volume. The volcano at Yellowstone is capped by enormously heavy rock. They worry about a big enough quake to break it right now because of the inflation rate on the larger estimation for the magma/gas  interactions. If we go and puncture that thing, it might just be a small erupton, but the alternative would be using the English scientist's design to pull electircity from the air. It's real, but hydrocarbon companies have a lot of pull with governments. It would be safer at this point, but to give it out makes it almost free but for a small unit on the side of the house, and Yellowstone will blow or get used for your idea before that will happen, as histor supports, I'm afraid. The same reasn geo-thermal isn't exploited more, not enough cash at end-product.

Mike DuBaldi
Mike DuBaldi

@william wong  Well if that were practical it would assure our safety. However another magma chamber would form half a million yrs down the road because of the hot spot under the crust over there.

Mike DuBaldi
Mike DuBaldi

@MICHAEL LETHER  Mantle material is closer to the surface under yellowstone; which melts crustal rock causing the accumulation of a magma chamber over time . This is called a "hotspot"

Tim Rafferty
Tim Rafferty

@Mark LordI agree, there are many creepy people that espouse such views. Seems as if on the large part they are of the liberal bent.  The cap and trade scheme is a perfect example, they cause a panic about global warming so they can make a market in phony carbon trading all the while enjoying the amenities of their multiple mansion and fleets of jets.

Tim Rafferty
Tim Rafferty

@Anlia Stewart Bolingerso then the inevitability of the demise of the puny humans assures that what you now consider planet abuse is not an issue.  The planet according to you is destined for destruction and any impact we have is actually so small it doesn't make a difference.

Tim Rafferty
Tim Rafferty

@Jose GomezLook at it this way, the odds of winning the last 600,000,000 dollar jackpot was far higher and two people won it last week.

F. Manzat
F. Manzat

@Mike DuBaldi@MICHAEL LETHER


That's really interesting. Is Yellowstone the only place where this occurs in the world or is it more common? I guess what I'm saying is; is Yellowstone the only huge super volcano in the world that is currently a threat?

Jeff Shikany
Jeff Shikany

@Tim RaffertyRafferty Wow, seismographs help identify where and when a meteor is going to hit?  Someone tell NASA! 

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