Yellowstone's magma reservoir gets bigger

The reservoir of molten rock underneath Yellowstone National Park in the United States is at least two and a half times larger than previously thought. Despite this, the scientists who came up with this latest estimate say that the highest risk in the iconic park is not a volcanic eruption but a huge earthquake.


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Yellowstone is famous for having a ‘hot spot’ of molten rock that rises from deep within the planet, fuelling the park’s geysers and hot springs1. Most of the magma resides in a partially molten blob a few kilometres beneath Earth’s surface.

New pictures of this plumbing system show that the reservoir is about 80 kilometres long and 20 kilometres wide, says Robert Smith, a geophysicist at the University of Utah in Salt Lake City. “I don’t know of any other magma body that’s been imaged that’s that big,” he says.

Smith reported the finding on 27 October at the annual meeting of the Geological Society of America in Denver, Colorado.

Yellowstone lies in the western United States, where the mountain states of Wyoming, Montana and Idaho converge. The heart of the park is a caldera — a giant collapsed pit left behind by the last of three huge volcanic eruptions in the past 2.1 million years.

Underground mapping
Jamie Farrell, a postdoctoral researcher at the University of Utah, mapped the underlying magma reservoir by analysing data from more than 4,500 earthquakes. Seismic waves travel more slowly through molten rock than through solid rock, and seismometers can detect those changes.

The images show that the reservoir resembles a 4,000-cubic-kilometre underground sponge, with 6–8% of it filled with molten rock. It underlies most of the Yellowstone caldera and extends a little beyond it to the northeast.

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Above the buried blob — in the topmost 5–10 kilometres of the crust — the rocks are cooler and more brittle, and fracture easily in earthquakes. Yellowstone is known for its swarms of earthquakes — in recent years, the Utah team has discovered tiny quakes that repeat as often as every few seconds2. Volcanic fluids build up in the crust and the small earthquakes probably act as relief valves to release the pressure. “It’s a living, breathing, shaking and baking place,” says Smith.

Yellowstone’s last mammoth volcanic eruption took place 640,000 years ago. Since then, some 50 to 60 smaller eruptions have occurred, with the most recent of these about 70,000 years ago. A much more likely risk than volcanoes, says Smith, is posed by earthquakes of magnitude 7 or greater like those that have struck the region in modern times. “They are the killer events which we’ve already had,” he says. For instance, the magnitude-7.3 Hebgen Lake earthquake that hit near Yellowstone in 1959 killed 28 people.

This area of the western United States is being stretched and thinned by geological forces, causing the crust to fracture in large quakes. The risk of more of these quakes occurring remains high, says Smith, making them a much bigger problem than any chance of a mammoth eruption.

The work underscores just how much remains to be learned about some of the world's most iconic volcanoes. A second study at the meeting, led by Aaron Pietruszka of the US Geological Survey in Denver, looked at the famous Kilauea volcano on the Big Island of Hawaii. Analyses of isotopes of lead in Kilauea's magma suggest it erupted from two small magma reservoirs just beneath the summmit. Volcanologists knew these two magma bodies were there, but the new work indicates the shallower one is smaller than scientists had thought.

www.nature.com...

Ugh...this is not good news...or is it?

Rainbows
Jane

well the latest swarm is at the eastern uplift..

www.seis.utah.edu...
keep the fingers crossed :-)

Well this news is 50/50, it could mean we have more time be for it blows but it would be much bigger then expected, or it could just be bad since we don't know what the limit of the area is or what it's max is. This would also change the spot i which it could blow at depending on what they find on the mapping.

I think most people understand that when it does go no one is going to be happy about it, just no clue when it will.

I have turned into a monster lately. I actually look forward to a huge quake occurring so we have something to talk about. I like to observe how screwed up our response to disasters is worldwide. learning of how we screw up should make our response better, but it seldom does because some people up high are more worried about economy stimulation and money than they are about helping people. What happened to us, we should take advise from the Amish, not rely on businesses and insurances to fix things. The problem is that the system is now made to promote businesses, not to help each other.

Sorry for being so off topic. Just had to get this off my chest. S&F

reply to post by rickymouse


Absolutely! Couldn't agree more......
U2U'd you a piccy..



Rainbows
Jane

So did it actually get bigger or did the scientists get it wrong in the first place. Until that is clarified, tomorrow is just as vulnerable as yesterday was, no more and no less, at least based on the size of the magma.

I've seen maps of the plume that make it seem more deep than it is wide. I hope Smith will revise that if his assessment has changed. It will better help to understand earthquakes near or even a bit beyond that. Idaho for example (last Spring and Summer) was probably unrelated but I know the thought crossed my mind - that it could be pressure from a couple of hundred miles up the road.

It doesn't really matter what size it is. It was already big enough that any eruption was going to pretty much put the hurt on civilized life around the globe especially since we've gotten arrogant enough in our modern lifestyle to think such things as food stores are passé.

For most of us, a single failed harvest or two will mean famine worldwide. And the kind of widespread climate disruption that a Yellowstone eruption could and probably would cause would do that.

Another fear would be the start of an actual Ice Age. If we actually are heading into a Maunder Style minimum with our Sun, then the type of large scale volcanic climate disruption a supervolcanic eruption like Yellowstone could produce could potentially flip the climate switch all the way over into large scale glaciation and Ice Age, and that would make anything I described up above seem like a party-happy-fun-time.

Of course, there is no telling if we are actually headed into a Maunder Minimum at the moment, and we won't know that for sure until we get four to five more years under our belts with the Sun continuing in its current funk. But right now, the current pause and cooling trend in global temps looks like it might be starting. More and more scientists are starting to whisper about it. So now more than ever, we need to worry about major volcanism.

StoutBroux
So did it actually get bigger or did the scientists get it wrong in the first place. Until that is clarified, tomorrow is just as vulnerable as yesterday was, no more and no less, at least based on the size of the magma.

only YVO knows that......and they wont tell it untill she goes...