Yellowstone Volcano

A super eruption of the Yellowstone Volcano.

This is no mystical doomsday prophesy – it is a real threat that will happen. According to the scientists an eruption is overdue...

Watch Supervolcano: The Truth About Yellowstone

Super Eruptions

The problem with Super Eruptions is they are impossible to predict.

But here are some facts that the scientists do know:

The magma chamber below the Yellowstone volcano is approximately:

  • 40 kilometers (25 miles) wide
  • 80 kilometers (50 miles) long
  • 8 kilometers (5 miles) deep

To put these statistics into perspective that is: more than 3 times the size of New York City.

What Is A Supervolcano?

To be classed as a Supervolcano, the chamber has to be big enough to contain a certain amount of magma that could be erupted.

The amount of magma needed to erupt to qualify as a Super Eruption is

1000 cubic kilometers
(240 cubic miles)

The amount of magma held in the caldera under Yellowstone is around

5000 cubic kilometers
(1200 cubic miles)

Pyroclastic Flow

The real threat comes from Pyroclastic Flow: rock, gas and ash exploded from the volcano.

When inhaled the ash combines with the fluid in the lungs forming a cement-like mixture.

A pyroclastic flow can move at speeds of up to 700 kilometers/hour (435 mph).

Yellowstone Volcano Eruption Effects

If the Yellowstone volcano erupts big time, it would explode the 2000-3000 cubic kilometers (480-720 cubic miles) of rock, gas and ash contained in the caldera.

To gauge what the effects of an Yellowstone volcano eruption would be like, scientists look to the first Yellowstone Super Eruption of 2.1 million years ago as this is the one they have the best data for.

Should a new eruption follow a similar pattern the effects across the US in the following zones would be:

Zone 1:
North West corner of Wyoming

Within a radius of 100 kilometers (63 miles) of Yellowstone – everything would be wiped out by the pyroclastic flow.

A quarter of Wyoming (north west)
Part of Montana (south west)
Part of Idaho (north east)

Everything and everyone trapped by heavy ash fall at least 100 cm (39 inches).

Western half of Wyoming
Southern half of Montana
Eastern half of Idaho

Everything and everyone trapped by heavy ash fall 61cm (24 inches).

All of Wyoming, Montana, Idaho and South Dakota
Half of North Dakota, Nebraska, Utah and Colorado
The north east of Nevada

Ash fall 15 cm (6 inches) – combined with rain this is enough to collapse a roof.

All of Wyoming, Montana, Idaho, South Dakota, North Dakota, Nebraska, Iowa, Utah and Colorado
Most of Kansas and Minnesota
Eastern half of Oregon
South east corner of Washington
Western half of Wisconsin
Northern third of Missouri
North west corner of Illinois

Ash fall 5 cm (2 inches) This area includes the grasslands. Animals grazing would be killed. This is the grain belt which means the food is gone.

Zone 6:
All of the above and then spreading out and extending as far as the eastern seaboard – pretty much everywhere else in the US.

Ash fall 1 cm (0.4 inches) – it only takes 1 mm (0.04 inches) of ash fall to ground planes and close an airport.

Then, as long as 7 days after the Yellowstone caldera eruption begins, the pressure holding the column in the air would finally drop bringing an end to the eruption and causing the column to collapse sending out a pyroclastic surge radiating over 100 miles from the base of the column.

What happens in the US after the Yellowstone volcano erupts?

Even more than what happens during a Supervolcano Eruption it’s what happens after that is most concerning.

It will take weeks, if not months, to rescue the 29 million people in the US closest to the volcano trapped by fallen ash.

The cleanup would be immense:

  • 80% of the US would be covered with ash
  • 30% of the US would be unusable or uninhabitable
  • Livestock in their millions would lie dead where they fell

Cities permanently abandoned would include:

  • Billings, Montana
  • Cheyenne, Wyoming
  • Denver, Colorado
  • Salt Lake City, Utah

What happens around the globe after Yellowstone erupts?

  • Around a month after the eruption ends billions of tons of sulphur dioxide ejected by the volcano would travel around the northern hemisphere cutting down the sunlight.
  • Within weeks the temperature would plummet by around 20 degrees plunging the northern hemisphere into a global volcanic winter.
  • Then the southern hemisphere would cool.
  • Monsoons in India would fail, bringing drought.
  • It would take years – decades even, before the planet’s climate would return to normal.

Remember, this is not another mystical apocalyptic prophesy.

I’m not suggesting it will happen tomorrow or even this year. But...


So at the very least, be sure to have a Bug Out Bag ready...

Watch the BBC Docu-Drama Supervolcano

These facts were dramatically illustrated in the BBC docu-drama, Supervolcano, originally shown over two nights in 2005.

Supervolcano: Part 1

Supervolcano: Part 2

Supervolcano: Part 3

Supervolcano: Part 4

Supervolcano: Part 5

Supervolcano: Part 6

Supervolcano: Part 7

Supervolcano: Part 8

Supervolcano: Part 9

Supervolcano: Part 10

Supervolcano: Part 11

Supervolcano: Part 12


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Yellowstone Webcams



The effects of the Yellowstone volcano erupting were dramatically illustrated in the BBC docu-drama: Supervolcano.

Unlike a Hollywood disaster movie, Supervolcano is scientifically accurate.

The BBC followed Supervolcano with a documentary that backs up the science in the docu-drama.