How Earth's devastating super-volcanoes might erupt

Jan 14, 2014 by Simon Redfern, The Conversation
Thank goodness Mount Sinabung isn’t a supervolcano. Credit: Binsar Bakkara/AP

Devastating supervolcanoes can erupt simply due to changes that happen in their giant magma chambers as they slowly cool, according to a new study. This finding marks the first time researchers have been able to explain the mechanism behind the eruptions of the largest volcanoes on Earth.

Geologists have identified the roots of a number of ancient and possible future supervolcanoes across the globe. No supervolcano has yet exploded in human history, but the rock record demonstrates how devastating any eruption would be to today's civilisation. Perhaps most famous is the Yellowstone supervolcano in Wyoming, which has erupted three times in the past two million years (the last eruption occurred 600,000 years ago).

These giant volcanic time bombs seem to explode once every few hundred thousand years, and when they do, they throw huge volumes of ash into the sky. At Yellowstone, the eruption that happened two million years ago ejected more than 2,000km3 of material – enough to cover Greater London in a mile-thick layer of ash.

It is estimated that a super-eruption like that would drive a global temperature drop of 10˚C for more than a decade. Such a dramatic change in global climate is difficult to comprehend. Aside from the instant local devastation, there would be global impacts such as crop failures, followed by large famines.

Despite their potential threat, comparable to a large asteroid impact, the mechanisms and origins of super-eruptions have remained obscure. Modestly sized volcanoes operate on different time-scales and magnitudes, and their eruptions appear to be triggered by pulses of molten rock (), which increase the pressure in the underground that feed their vents.

Two papers recently published in the journal Nature Geoscience try to solve the mystery of how super volcanoes are formed and how they erupt.

An artist’s impression showing the magma chamber of a supervolcano with partially molten magma at the top. The pressure from its buoyancy is sufficient to punch through 10km or more of the Earth’s crust above it. Credit: ESRF/Nigel Hawtin

Using experiments and computer modelling, scientists have discovered what drives a super-eruption. They find that, over time, the underground magma becomes increasingly more buoyant. Eventually, it becomes a bit like a beach ball held down beneath the waves—when it is released, it shoots into the air, forced up by the dense water around it.

In the first paper, a team led by Wim Malfait and Carmen Sanchez-Valle of ETH Zurich used a synchrotron (an accelerator that can generate intense X-rays) to measure the density, temperature, and pressure of molten rock held in conditions resembling those of a magma chamber several kilometres below the surface. This required them to mimic deep Earth conditions in the lab at the European Synchrotron Radiation Facility, holding samples at temperatures up to 1,700˚C and the pressure of 36,000 atmospheres.

To feed a supervolcano you need a huge magma chamber. The Zurich team's results show that, as the magma chamber cools, it begins to solidify and crystals grow in it that are denser than the magma. As these fall to the base of the chamber, the remaining molten rock gets progressively less dense. If there is enough of it, their measurements indicate that the magma eventually becomes light enough that it can force its way through more than 10km of Earth's overlying crust.

Co-author Carmen Sanchez-Valle, also at ETH Zurich, said: "Our research has shown that the pressure is actually large enough for the Earth's crust to break. As it rises to the surface, the magma will expand violently, which is a well known origin of a volcanic explosion".

The second paper by Luca Caricchi and colleagues at the University of Bristol, describes computer simulations of the same processes, finding that the buoyancy of melt in maturing magma chambers is also key to these huge events.

This contrasts with the way that more familiar smaller volcanoes erupt. There, blasts follow directly from rapid injections of magma, or from external events that release the pressure on it, such as earthquakes or even the melting of overlying glaciers, as seen in Iceland recently.

The results indicate that supervolcanoes just require a steady accumulation of that remains hot enough that it does not completely solidify—a massive eruption is then simply a matter of time. Thus, the eruption of massive supervolcanoes seems to be an inevitable part of their "life cycle". Just as a sufficiently large star will necessarily generate a supernova, so a huge magma chamber should eventually become a massive eruption.

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mosahlah
1 / 5 (1) Jan 14, 2014
And that's bad news. I suspected the geothermal siphoning strategy suggested by some to reduce the possibility of an eruption of Yellowstone might have a paradoxical effect. I guess we will just have to accept that someday, everything we as a nation worked so hard for, will be for naught. This is a good point to start eliciting survival strategies from the well informed. Anyone? A cellar in Australia packed with dried food?
Shakescene21
1 / 5 (3) Jan 14, 2014
It's bad news but not as hopeless as the worst pessimists are suggesting. If you read the last paragraph carefully, you'll note that a key condition of a supervolcano is that the molten rock has to remain hot enough that it does not completely solidify. So it would seem that a geothermal siphoning strategy could prevent the eruption if it removed heat rapidily enough that the magma solidified.
mosahlah
1 / 5 (1) Jan 14, 2014
And how do you do that?
TheGhostofOtto1923
3.7 / 5 (3) Jan 14, 2014
"No supervolcano has yet exploded in human history" -Prehistory you mean...

"Taupo in New Zealand erupted about 26,500 years ago, but the most devastating supervolcanic event in human history was Toba. Located on Sumatra, this massive volcano erupted some 70,000-plus years ago, triggering a volcanic winter that may have affected global temperatures for thousands of years."
geothermal siphoning strategy
Youre still a fucking retard arent you? Or just a sorry troll?

"The most detailed seismic images yet published of the plumbing that feeds the Yellowstone supervolcano shows a plume of hot and molten rock rising at an angle from the northwest at a depth of at least 410 miles, contradicting claims that there is no deep plume, only shallow hot rock moving like slowly boiling soup."

For the curious, this thread shows how blindingly ignorant or simply malicious a poster can be:
http://phys.org/n...ght.html
Shakescene21
1 / 5 (2) Jan 14, 2014
@mosahlah-- At this stage the most likely method of extracting the heat from Yellowstone would be to generate geothermal electricity on a vast scale. Sale of "green" electricity would hopefully pay the cost of the vast project, and replace most of the fossil fuels America currently burns.
TheGhostofOtto1923
4 / 5 (4) Jan 14, 2014
@mosahlah-- At this stage the most likely method of extracting the heat from Yellowstone would be to generate geothermal electricity on a vast scale. Sale of "green" electricity would hopefully pay the cost of the vast project, and replace most of the fossil fuels America currently burns.
@mosahlah - pussytard wants to run cooling pipes through magma 10 miles below a national park. Over an area 1500 sq mi. To somehow significantly cool molten rock the volume of many mountain ranges.

Isn't that right pussytard aka pussycat_eyes aka pirouette aka ritchieguy aka Obama_socks aka the biggest imbecile on the internet?

Of course if we enact your vision of zero growth, meaning no new kids for 100 years, then an eruption shouldn't be a problem anyway.
TheGhostofOtto1923
4 / 5 (4) Jan 14, 2014
But with this substantially ignorant statement
And that's bad news. I suspected the geothermal siphoning strategy suggested by some to reduce the possibility of an eruption of Yellowstone
-I have to suspect you're part of the joke? Perhaps the joke itself? The joke talking to itself ?
mosahlah
5 / 5 (1) Jan 15, 2014
Otto, man. I love when you talk dirty. Why can't I meet folks like you in person? Everyone I know is so respectful. We should meet and talk about personalities.
TheGhostofOtto1923
3.8 / 5 (4) Jan 15, 2014
Otto, man. I love when you talk dirty. Why can't I meet folks like you in person? Everyone I know is so respectful. We should meet and talk about personalities.
Guaranteed I am the same in person as I am here. Ignorance is bliss eh? Even though it causes others pain. I enjoy making offenders feel the pain they inflict on others. In this I think I am providing a valuable service. For instance
I suspected the geothermal siphoning strategy suggested by some to reduce the possibility of an eruption of Yellowstone
-This pains me. Who is the 'some' you are talking about? Who could possibly think that anything we could do could affect this much molten rock in any way whatsoever? You have any refs you'd like to post? Any calcs you'd like to share?

Read the other thread. Ask yourself why you're encouraging such ignorance. Do your part to stop the pain.
Budding Geologist
not rated yet Jan 18, 2014
Even if they did find some way to pipe water for geothermal energy all the way down to the yellowstone caldera, in order to accelerate the cooling this would make the eruption sooner, not prevent it from occurring. What the researchers are suggesting triggers supervolcano eruptions, is the process of differentiation, as opposed to magma input to the magma chamber as found in other types of volcanos. In differentiation as the magma chamber cools, iron, and magnesium rich minerals, which are relatively dense, crystallize at higher temperatures, leaving an increasingly silica rich melt which is less dense, and more buoyant compared to the surrounding crustal material. They are suggesting this causes the magma to rise and increases pressure ultimately allowing the silica rich melt to reach the surface. @GhostofOtto, do you need to be such an ass while making your point? If you want to educate that is not an effective approach.
Captain Stumpy
not rated yet Jan 18, 2014
@GhostofOtto, do you need to be such an ass while making your point? If you want to educate that is not an effective approach

@Budding Geologist
you have been here longer than i. surely you can see that he will not stop.

also, given that there really are some remarkably stupid comments made about things, especially that
geothermal siphoning strategy

with no references or math to back up the insanity, then when others, like you or?, gently prod with
Even if they did find some way to pipe water for geothermal energy all the way down to the yellowstone caldera, in order to accelerate the cooling this would make the eruption sooner, not prevent it from occurring


they cannot accept the logic... therefore ...???

if you cant convince them with logic, you use whatever else is available.
Shakescene21
1 / 5 (1) Jan 18, 2014
@Budding Geologist -- I hope you become a geologist, and maybe even become involved in saving hundreds of millions of lives by converting this supervolcano monster into a vast source of green electricity.

These geologists have identified an important source of supervolcano eruptive power, but it is a simplistic model. For example, compare their simple diagram of a supervolcano with with the latest actual diagram of Yellowstone's magma chamber in this article:

http://phys.org/n...ght.html

Because of tectonic plate movement over the years, the magma chamber is far mor horizontal than the stylized chamber the the authors present. The real world is more complicated, and there are other forces at work besides the "bouyancy effect" that these geologists have presented in their paper.

Shakescene21
1 / 5 (1) Jan 18, 2014
Regarding the trends which will cause the Yellowstone Supervolcano to erupt, in my opinion the most dangerous trend in the geologic short run (ie, 100 to 1000 years) is the steady melting of the continental sheet of rock over the magma chamber, which USGS estimates to be around 4 to 6 inches per year. Eventually this cover will be so thin that the volcano will be able to push through it and erupt. This is probably more urgent than the steady build-up of bouyant magma that is being pushed upward by heavier magma.

It seems to me that the smartest course of action would be to drill into the hot rock and cool the rock enough to keep it from melting, by extracting steam which would produce geothermal energy. The drillers in the Marcellus Shale formation are currently drilling a mile deep and then drilling sideways for a quarter mile, so the technology is not inimaginable.

There are other strategies, including taking advantage of the horizontal shape of the Yellowstone chamber.

Shakescene21
1 / 5 (1) Jan 19, 2014
"Even if they did find some way to pipe water for geothermal energy all the way down to the yellowstone caldera..."

@Budding Geologist -- Rather than pipe water into the caldera, geothermal collection tubes would be in the hot-but-solid rock above the caldera. A mile or two deep would probably be sufficient at first. This energy extraction would strenghten the rock that is holding the magma down and also slow the flow of melting tectonic plate rock into the magma chamber.

The researchers' model does not discuss the process by which the solid rock from above is gradually melting and liquifying to become part of the magma in the expanding chamber. This liquified rock then becomes fresh magma which differentiates into heavy and lighter fractions, which expands the bouyant force pushing upward. (This is in addition to magma which is trying to enter the Yellowstone magma chamber from below.) Thus, cooling the hot rock layer above the magma chamber delays the eruption in two ways.
Whydening Gyre
5 / 5 (1) Jan 19, 2014
"Even if they did find some way to pipe water for geothermal energy all the way down to the yellowstone caldera..."

Had a boil when younger. Cool rag made it feel good for a little bit, but it got bigger and redder after a few minutes. According to my grandma (a pretty common sense North Dakota farmer) the only proper way to alleviate the pain (caused by the pressure buildup) was lancing - alleviate the pressure in a controlled way... She got out a needle and went to work. in 20 seconds I felt relief.
Pick a spot and drill a hole or 2, I say.
TheGhostofOtto1923
3.7 / 5 (3) Jan 19, 2014
@GhostofOtto, do you need to be such an ass while making your point? If you want to educate that is not an effective approach
You bet. Read the other thread. Do a search for Obama_socks comments. We are WAY beyond cordiality here. This poster thinks an Antarctic ice shelf can be melted by one geyser. And then has the audacity to insist that she's a NASA engineer.
hot-but-solid rock above the caldera. A mile or two deep would probably be sufficient at first.
Magma begins 10 mi down. Caldera is 1500 sq mi. The magma itself is 4000 cubic kilometers and is constantly churning due to convection and conduction and differentiation.

Pussytard you are blazingly ignorant or you are pretending to be so for thrills in typical grade school fashion. Are you having fun you vandal?