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Why the A-10 Warthog Is a Ground Soldier’s Best Friend

NARRATOR: Recently, scientists have collected new data

giving them a better picture of Yellowstone's

underground plumbing.

Right beneath the caldera, from the last eruption,

sits the magma chamber.

And it's fed by a plume of magma stretching down 465 miles,

northwest into Montana.

It's mostly solid rock, with the potential to liquefy.

And scientists are closely monitoring it.

Magma, or molten rock, is rising through the plume

into the magma chamber at 2 inches a year.

There's no reason for it to stop

or it might come in spurts.

Our images show wider parts and narrower parts.

So it's like slugs of material that

are flowing in a sewer line.

And this restless Yellowstone Caldera

is truly living, breathing.

And every once in a while, it burps.

NARRATOR: The danger is that the plume starts liquefying

and moving up at a faster rate.

Natural systems can throw us a lot of curve balls.

A lot of things can happen that we're not really ready for.

NARRATOR: Scientist Jake Lowenstern

is looking for a pattern connecting

this supervolcano today and its three prior major eruptions,

2.1 million years ago, 1.3 million years

ago, and 640,000 years ago.

JAKE LOWENSTERN: In two of the really large eruptions

at Yellowstone so much material comes out,

entire mountain ranges end up falling into the ground

and essentially disappearing.

NARRATOR: One 50-mile stretch of mountains

simply disappeared by collapsing into the magma chamber.

University of Toronto geologist John Westgate

has tracked the ash from Yellowstone's prior eruptions.

JOHN WESTGATE: It covered much of the United States.

It occurs right out of the Pacific Ocean.

It's even found in the Gulf of Mexico.

Up in northeast Montana is the site that we're working on.

The total is over 7 meters thick.

These eruptions are enormous.

The amount of material erupted from them, huge.

NARRATOR: When Mt.

St. Helens erupted in May 1980, it

blew up one side of the mountain and triggered an avalanche

of snow, mud, ash, and rock.

Driven by the wind, the ash landed in 11 states

and up in into Canada.

But that's nothing compared to the amount

of ash from Yellowstone's last three major eruptions.

In magnitude and volume, each one was far greater than Mt.

St. Helens.

Today, there's little evidence of the supervolcano's

violent past.

The 50 by 30 mile caldera from the last eruption

was covered by lava and ash and smoothed over by glaciers.

Forests now conceal the scars.