All language subtitles for Yellowstone; The Eruption That Would Bury America in Ash (S1, E7) ¦ Mega Disasters ¦ Full Episode (inglés)

[intense music]

NARRATOR: Yellowstone,
America's first national park,

and home to one of the world's
largest super volcanoes.

Beneath the scenic
geysers and waterfalls,

an eruption a thousand
times larger than any

in human history awaits.

It's happened before.

Less than a million years ago,
it devastated more than half

the continent, and it
could happen again.

There will definitely
be additional eruptions

in this area.

NARRATOR: And not
just one, but a series

of monstrous eruptions--

a million times more
powerful than an atomic bomb.

MICHAEL RAMPINO: It's
absolutely devastating.

Everything would be killed.

NARRATOR: Destroying
thousands of square miles

of land and countless
lives across the northwest.

It'll just be over.

It'll be toast.

It'll be finished.

NARRATOR: We go
beneath the earth

to probe the volcano,
revealed for the first time

the source of its power to
discover what will happen when

the sleeping giant
of Yellowstone

awakens and becomes
a mega disaster.

[theme music]

The dance of geezers is one of
nature's greatest spectacles--

it's why millions of
visitors each year

come to America's oldest
national park, Yellowstone.

Its spectacular beauty inspired
President Ulysses S. Grant

to protect these two million
acres of northern Wyoming

wilderness back
in 1872, and it's

been a haven for outdoor
enthusiasts ever since.

Its incredible hot
springs, bubbling

pools of mud, unearthly
ponds, and the most celebrated

natural feature, the
Old Faithful geyser

are some of nature's
greatest wonders.

But beneath this primal beauty
simmers a hidden threat.

Five miles below the
waterfalls and mountain peaks

lies the heart of a super
volcano, a constantly moving

cauldron of molten rock
the size of Mount Everest.

Over countless
millions of years,

it fills with lava to
the breaking point.

Like a bomb with a hidden
timer, it finally explodes.

We don't know how long
it's going to just sit there

before it decides to go off.

NARRATOR: If sometime in
the future it were to erupt,

as it has before, the
Yellowstone volcano

would overwhelm everything
within 100 miles

and disrupt lives across
the globe for years.

The first sign of trouble will
be increasing seismic activity.

The ground would rise as
pressure from the molten rock

begins to grow.

There would be a lot
of ground defamation,

and then if it was
moving up slowly enough,

we would actually start seeing
large changes in the geyser

basins.

NARRATOR: Finally, the lava
would shatter the earth's

surface with an
explosion 10 times larger

than Mount St. Helens.

A hurricane of hot gases would
spread out in all directions

as the ash cloud reaches
80,000 feet into the air.

Already larger than anything
man has experienced,

this would be just the
beginning of a Yellowstone

super eruption.

Within days, a second
enormous eruption

would begin, then another.

Soon, a ring of monstrous
explosions 50 miles wide

would be spewing molten
rock and burning gases

across the landscape.

Certainly within 100
miles at Yellowstone,

there wouldn't be much
that was not destroyed.

NARRATOR: High in the
atmosphere, the ash cloud

would surround the planet,
sending temperatures plunging.

Global agriculture
would fall into chaos.

How do we know it will happen?

Because it's happened before.

The evidence is etched
into the geologic record

of past super volcanoes.

There are 1,500 volcanoes
around the world,

but there are fewer than 10
super volcanoes, the ones

with the potential to not only
destroy the surrounding area,

but to create a global
disaster, and Yellowstone is

one of these super volcanoes.

Imagine something 10,000 times
the size of Mount St. Helens.

It's almost unimaginable.

NARRATOR: Unlike a conventional
volcano with its crater

atop a mountain, Yellowstone's
crater is so large,

it can only be
seen from the air.

This is the rim of a monstrous
crater called a caldera that

collapsed into the magma chamber
during the last super eruption.

It's large enough to hold
the city of Los Angeles.

People drive 35 miles,
45 miles commuting

to work in that.

Well, that's the distance
across this caldera.

NARRATOR: And this
is only the last

of three monstrous calderas
formed over the past two

million years.

The volcanic
history of Yellowstone

is really marked by these three
giant cataclysmic eruptions

of the scale that we haven't
seen in the history of man,

really.

The first eruption
vented somewhere around 600

cubic miles of material.

And if you took all of
that and you spread it out

over the state of Texas,
you'd have about 12-feet thick

of deposits.

NARRATOR: The second eruption
was hundreds of times

larger than Mount
St. Helens, and it's

the smallest of the
Yellowstone super eruptions.

The most recent one, known
as the Lava Creek eruption,

occurred 640,000 years ago.

At the time, early man had
yet to arrive on the scene.

Exotic prehistoric animals
roamed the North American

continent.

Five miles beneath the earth,
however, a magmatic cauldron

three times the size of New
York City was coming to a boil.

There would have been hundreds
to thousands of earthquakes

becoming fairly
large, so there'd

be a lot of shaking as the
hot rock was moving up.

NARRATOR: A million tons of
molten rock heated to 1,800

degrees Fahrenheit pressed
its way to the surface.

Jets of superheated
water suddenly burst

through the cracks in
the earth's surface,

shooting into the air.

Hundreds of geezers were
erupting over 500 square miles.

JACOB LOWENSTERN:
We get explosions

out of the hydrothermal system
that put holes in the ground

as big as a mile across,
they they're big events.

NARRATOR: But this was just the
overture before the main event.

After days of increasing
earthquake and geyser activity,

under mounting pressure from
magma and superheated gases,

Yellowstone's last
super eruption began.

ROBERT SMITH: Material may
have started to leak out

of one side, perhaps
forming part of the edge

of the fracture zone.

As you start to
decrease the pressure,

it starts to then explode.

NARRATOR: With the power
of a hydrogen bomb,

a monstrous cloud of
searing ash and melted rock

shot into the stratosphere
at supersonic speeds.

The heavier debris fell
back to the ground,

turning into colossal
pyroclastic flows.

MICHAEL RAMPINO: It was
sort of like a hurricane

made up of 800 degree ash,
and pumice, and hot gases.

Just wipes things
out completely.

NARRATOR: For miles, these
lethal rivers of ash and gas

cooked animals alive and brushed
forests aside like twigs.

ROBERT SMITH: They
extend, actually,

outside of Yellowstone into
Idaho and into the Teton

region.

Some of this material flowed
down and actually covered

parts of the floor
of Jackson Hole,

so these scenes
extend tens of miles

away from the actual
eruption location.

NARRATOR: For days,
the Yellowstone volcano

continued to heave tons of
molten debris into the air

and devastated the
nearby terrain.

Then, across the caldera,
another colossal explosion,

then another.

Eruption after eruption began
shooting more and more lava

and pulverized
rock into the air.

JACOB LOWENSTERN: Typically,
when these eruptions begin,

they begin at a single
event, and the event may then

get larger, moving out along
some sort of a fracture system.

NARRATOR: Yellowstone had
turned into a super eruption.

Its devastation would
reach around the world.

Yellowstone's last
super eruption

occurred 640,000 years ago.

It started as a single
massive volcano,

but soon turned into
a series of eruptions,

exploding with the full
force of a super volcano.

Entire sequence of
pyroclastic explosions

that formed the Yellowstone
caldera may have taken as

little as two weeks to happen.

NARRATOR: Pyroclastic flows
slashed across the landscape,

obliterating thousands
of square miles.

Separate clouds of ash fused
into a massive column of smoke.

Winds drove it
across the country,

darkening the sky for
hundreds of miles.

During the eruption
of all this material,

that's when the caldera
would have started forming.

NARRATOR: In a final massive
display of nature's fury,

hundreds of square
miles of mountain

dropped thousands of feet
into the pit of roiling magma.

ROBERT SMITH: The Gallatin
range, the Madison range,

and the Mount Washburn range to
the north continued somewhere

into the Yellowstone region.

These mountain ranges
were destroyed.

Now, when I say
destroyed, I don't

mean they were
blown to smithereens

into the atmosphere.

Much of it just then just fell
back into the magmatic system,

just fell back into the
cauldron, if you wish,

of the caldera itself.

JACOB LOWENSTERN: We're talking
about mountains that might be

12,000 feet high that
are now at the ground

surfaces on the order of 8,000
to 9,000 feet high, so 3,000

foot mountain that
is no longer there.

NARRATOR: Finally, after perhaps
weeks of constant activity,

the Yellowstone volcano
subsided, but the devastation

was far from over.

A global disaster
was about to begin.

2 and 1/2 trillion tons
of sterile volcanic ash

drifted with the winds and
buried 2,000 square miles

of the North American
plains, destroying much

of the continent's plant life.

HANK HEASLER: The
volcanic ash that's

ejected high up
into the atmosphere,

and then falls many,
many miles away,

that goes as far as
Louisiana and some

of the states along the
Mississippi River, so quite

an ash cloud.

NARRATOR: The lighter
particles remained

in the air for more than a year,
forcing temperatures to plunge

across the hemisphere.

It acts as a veil and
cuts out the sunlight,

and so it cools
the climate below.

I think there were certainly
of been climatic changes

due to Yellowstone.

We estimated 3 to 5
degrees Celsius drop

in temperature, which is quite
severe on a global basis.

NARRATOR: 5 degrees
was enough to kill off

much of the tropical plant
life across the globe.

Over the next year, animals
died from lack of food

as the ash continued
to block out the sun.

It took years for the
planet to recover,

for sunlight to reach
the earth's surface,

for plants to push
through the layers of ash,

for animals to
repopulate the continent.

This Yellowstone eruption
640,000 years ago

changed the face
of North America,

but that wasn't the
only super eruption

to ever strike the area.

Besides the three calderas
found near Yellowstone park,

geologists have
discovered a series

of eruptions and super
eruptions that extend back

16 million years.

JACOB LOWENSTERN:
There have been

a series of volcanic eruptions
similar to those that occur

at Yellowstone, and there are
all sorts of calderas that

are preserved in the
Snake River Plain in Idaho

and extending back into Nevada.

NARRATOR: To date, 15
calderas of more than 140

large eruptions
have been mapped.

They create a trail running
Northeast to Southwest and

are an indication of what
geologists call a hot spot.

A hot spot is a portion
of the earth's mantle

that contains a massive
pool of partly molten rock.

JACOB LOWENSTERN: There is an
area within the earth's mantle,

deep underneath where
we live, that is molten,

and it's causing a lot of heat
to rise towards the surface.

And that heat causes
melting in the crust,

and so we get a
large magma chambers.

NARRATOR: From time to time,
as the pressures build,

the magma works its
way to the surface--

and explodes.

ROBERT SMITH: There
are 20 or 30 hot spots

around the earth's globe, such
places as Hawaii and Iceland.

These are long lived
zones of active volcanism.

NARRATOR: The Hawaiian
islands, for example,

were created one by
one over the millennia

by an underwater volcano.

Though it appears as if
the volcano had moved

along the earth's
surface, in reality,

the area of molten rock has
remained relatively stationary.

It is the earth's
crust which has moved.

The same is true for
the Yellowstone hotspot.

Above its magma chamber,
the North American plate

is slowly sliding to the
southwest, about an inch

a year.

With each new
eruption, a caldera

is formed, and appears to
be further to the north.

We find caldera as all the
way back into northern Nevada,

and it's possible
that there have been

as many as 50 eruptions just
as big as some of the ones that

have come out of Yellowstone.

NARRATOR: With a history of
multiple cataclysmic eruptions,

Yellowstone is becoming the
most studied super volcano

in the world, and its hundreds
of yearly earthquakes,

thousands of geysers,
and massive magma chamber

make it one of the most
geologically active regions.

This thing is a
breathing system,

and it's a dynamic system.

So I called it a living,
breathing, shaking caldera.

NARRATOR: At the heart
of these super eruptions

is thought to be a mantle
plume, an upwelling of molten

rock rising from deep
within the earth.

But no one could be sure.

Recently, however,
scientists have

been using extremely
sensitive monitoring systems

to capture data from earthquakes
centered around the world.

The data has helped create the
first 3D image of the source

of Yellowstone's power.

Once we put out an
array of seismographs

with sufficient resolutions,
like getting a high resolution

CAT scan, we saw that this
thing was going off laterally

about 150 kilometers
to the northwest.

And it is basically
coming up from the depth

of about 600 kilometers.

NARRATOR: Yellowstone's
magma source begins 450 miles

below the surface, and,
surprisingly, not directly

under the park,
but 150 miles away

beneath the
Montana-Idaho border.

It was totally
unexpected and would not

fit into anyone's
textbooks or classic ideas.

NARRATOR: As the
research continues,

scientists are realizing
how little they really know

about the Yellowstone volcano.

JACOB LOWENSTERN: Since humans
haven't seen an eruption

of this magnitude,
we're somewhat

challenged to know exactly
how the systems work.

NARRATOR: One thing
is known for sure,

if Yellowstone erupts again,
pyroclastic flows will destroy

everything near the volcano, and
its ash cloud would overwhelm

humanity across the globe,
and predicting its eruption

could be a matter
of life and death.

The ash from the last
three Yellowstone

eruptions would fill
the Grand Canyon.

Yellowstone, its
dreamlike natural beauty

may sometime in the future
turn into a nightmare.

With little warning,
the gigantic volcano

could awaken and explode,
putting the entire planet

at risk.

Unlike most disasters, such as
tornadoes or hurricanes, which

are short lived and localized,
a volcanic super eruption

in Yellowstone would have
global effects for years.

Its impact would be on the scale
of an asteroid, large enough

to change the way
we view our history.

For a long time,
the earth history

was gradual changes, slow
changes over long periods

of time, and now we realize that
every once in a while, boom,

out of the sky comes
something catastrophic.

NARRATOR: Most scientists
believe an asteroid caused

the disappearance of the
dinosaurs 65 million years ago,

but new discoveries suggest
volcanoes can cause planet

wide devastation as well.

One of the early volcanoes
fueled by the Yellowstone

hotspot left a
gruesome graveyard

a thousand miles downwind.

MIKE VOORHIES: 12 million years
ago, the wildlife in Nebraska

was similar to what we
have in Africa today.

We have elephants,
rhinoceroses, camels,

horses related to zebras,
all kinds of critters

that aren't here anymore.

NARRATOR: Their
bones, discovered

in northern Nebraska,
tell a distressing story

of Yellowstone's impact.

They were found buried under
several feet of ash, volcanic

debris linked to
a super eruption.

We first thought that
maybe all these critters

had been buried alive in ash,
like the people at Pompeii.

But the more closely we
looked at the fossils,

it turns out that
that wasn't true.

NARRATOR: Most of
the fossil bones

exhibited evidence of a
strange illness, a clue

to why so many animals died.

It has the extra growth
of bone on the leg bones

and on the jaws.

NARRATOR: The unusual bone
growth is a signature symptom

of Marie's Disease, a rare
lung condition resulting

from breathing large
amounts of dust or ash.

This is a jawbone of a
camel from the ash bed.

This shiny bone here is healthy.

It's normal, fossilized bone.

And you can see where
the healthy bone stops

and this new growth begins.

You can see the color changes
and the texture changes.

It looks like a sponge, and
this is the diagnostic feature

of HPOD, or Marie's Disease.

NARRATOR: Voorhies believes
that ash from the Yellowstone

hotspot caused Marie's
Disease in these animals.

MIKE VOORHIES: Ash is
nothing but very small

pieces of glass--

that's how you can tell volcanic
ash from other types of fine,

powdery rocks is that volcanic
ash sparkles because it's

made out of little
teeny pieces of glass.

NARRATOR: During
a super eruption,

the tremendous pressures caused
the molten rock to explode.

It turns the rock into
tiny pieces of glass

which drift with the wind and
land hundreds of miles away.

MIKE VOORHIES: Just as soon
as the volcanic ash fell,

the whole landscape, for
thousands of square miles,

was covered with this
very fine powder.

And every step that
those animals took,

they would raise a cloud of ash.

And they just kept breathing
it day, after day, after day,

so what we think
happened to the animals

is that they breathed this
material night and day

until their lungs just
gradually gave out.

NARRATOR: Most of the
animals on the Nebraska plane

suffocated on the ash within
a week of the eruption, this

from a super volcano
a thousand miles away.

Volcanoes can
kill at a distance.

I really wouldn't have bet
20 years ago that a volcano

a thousand miles away could
actually cause mass death,

but ash fall has made
a believer of me.

NARRATOR: More recently,
the 1815 eruption

of the Indonesian
island of Tambora

proved ash could kill indirectly
through dramatic climate

change.

50 times larger than
Mount St. Helens,

the impact of the Tambora
volcano was overwhelming.

The eruption reduced the
mountain by 4,000 feet

as nearly 150 million
tons of ash and debris

were ejected into the air.

The ash cloud could be
seen for hundreds of miles.

MICHAEL RAMPINO: The cloud went
over India, darkened the sky,

and caused the
temperature to go down.

The temperatures
went below freezing.

NARRATOR: It took almost
a year for the ash

to spread across the rest of
the globe, but when it did,

the results were staggering.

A New England newspaper from
1816 published this account.

MAN: Snow and hail began
to fall about 10:00 AM,

and the storm continued
till evening, accompanied

by a brisk wind.

NARRATOR: This was June 15.

There was, in some places,
essentially no summer.

In the eastern United States,
there was snow and ice

in June, July, August.

They replanted the crops.

The crops died.

They replanted them again.

NARRATOR: The unusually
frigid weather

reached Europe, some
9,000 miles from Tambora,

throwing life there into chaos.

1816 was the last time there
was widespread starvation

in Europe.

That's never happened since, and
it's almost certainly involved

with the eruption of Tambora.

NARRATOR: And the
Tambora eruption

doesn't begin to match
the fury of a Yellowstone

super eruption.

The Tambora eruption is on
the order of 50 to 100 times

smaller than these large
sort of super volcano

eruptions out at Yellowstone.

NARRATOR: Even smaller than
Tambora was the 1991 eruption

of Mount Pinatubo
in the Philippines,

which devoured villages
out to 200 miles.

Yet despite its
modest size, Pinatubo

altered the global
climate for years,

and has been linked to the
destructive hurricanes Andrew

and Iniki.

After the eruption
of Pinatubo,

there was a definitely
measurable change

in the global temperature as
a result of that eruption.

It was on the order of 2
degrees for the year following

the eruption.

NARRATOR: It may sound
trivial, but a 2 degree change

in global temperature
over a long time

could create unusually severe
storms and kill off all but

the hardiest plant life.

Pinatubo was a
hundred times smaller

than the last Yellowstone
super eruption

and had cataclysmic
effects across the globe.

Imagine what
Yellowstone would do.

In recent geological history,
only the colossal eruption

of Toba on the island of
Sumatra can match the size

of Yellowstone, and that
eruption, some 70,000 years

ago, may have nearly
destroyed the human race.

Well, Toba is the
largest super volcano

that we know about.

There is now a large lake called
Lake Toba which is the hole out

of which the eruption came.

NARRATOR: It likely
erupted for two weeks,

dropping ash 6 inches deep
on the subcontinent of India.

But Toba's greatest
impact was felt halfway

across the planet in Africa.

Around the time of
the Toba eruption,

it's thought the
population of early man

was catastrophically reduced.

It appears a bottleneck,
or a contraction,

of the human population
occurred, reducing our numbers

from possibly
hundreds of thousands

to just a few thousand.

We know from the genetic
data that something happened

in the human history, in
the history of our species,

that reduced the amount of
genetic variation a lot.

And the argument
is all about what

was the nature of that event.

One possibility is that there's
some catastrophe that happened

70,000 years ago, like the Toba
super volcano, that just wipes

out plants, and animals, and
humans all over the earth

until there's hardly
any of them left.

NARRATOR: The massive
eruption of Toba,

more than 25 times
larger than Tambora,

likely created a catastrophic
change in climate.

Ice core samples suggest that
the average temperature may

have dipped as much as
20 degrees for years

after the eruption,
likely killing off

plant life across the globe.

Hardest hit would have been
tropical areas like Africa.

Africa is where
we were at the time,

and so would affect us directly.

And secondly, it's the
tropical vegetation that never

experiences cold temperatures,
so it has no adaptations

for cold temperatures
whatsoever.

NARRATOR: The frigid
temperatures killed off

much of the African plant
life, and the resulting famine

may have decimated
much of the human race.

It may be that the 6.5 billion
people who inhabit the earth

today are the direct
descendants of the few

who survived the Toba eruption.

If a single eruption like
Toba is powerful enough

to almost destroy
the human race,

what would a similar
super volcano do today?

When a large, giant
eruption were to occur,

I think there's little
that man can do about it.

The biggest thing we have to
do first is understand them.

NARRATOR: That's why scientists
are studying every aspect

of the Yellowstone volcano.

What they discover may be
the key to our survival.

For most of us,
Yellowstone National Park

is one of our greatest
natural treasures,

but what lies just below the
surface could destroy it all.

The sense of scale of
the catastrophic eruptions

for Yellowstone is
very hard to grasp.

NARRATOR: 640,000 years ago,
a super volcano in Yellowstone

devastated the region.

Today, scientists monitor the
ground movement in Yellowstone

to determine if, and when,
another super eruption might

occur.

We don't know exactly what
happens before a super eruption

takes place and how much time
one has before the eruption

actually goes off.

NARRATOR: The rise and fall
of the ground, for example,

could indicate the movement of
magma below, a possible danger

sign.

These movements cover very short
distances over long periods

of time, so scientists have
placed throughout the park 12

global positioning satellite
monitoring stations that

can detect ground movements
within a quarter of an inch.

Geologists have also
gained a bird's eye view

of the situation.

We use satellites,
in this case,

to take pictures of the ground
as it's moving over time,

and so we can compare
two different passes

of the satellite that
are perhaps a year apart

and make a map of how much
different spots on the ground

have moved.

NARRATOR: With these
tools, geologists

have been able to
document changes

in the caldera, its constant
rising and falling over time.

According to recent satellite
data, much of the caldera

is being lifted up.

What we've seen has been
uplifting, now at rates

of 6 to 8 centimeters per year.

Those are very high rates.

NARRATOR: The most
dramatic uplift

is just north at Yellowstone
lake in the area geologists

call a resurgent dome.

ROBERT SMITH: And we
have, within this caldera,

these orange areas here.

These are resurgent domes.

These are areas that are
uplifted while the caldera was

collapsing and subsiding.

NARRATOR: Geologists believe
that these two areas were

lifted up by the magma chamber
as the caldera was formed.

It's thought that some magma
is still inside these domes,

holding up these areas.

But they couldn't
be sure until now.

We've seen this model of
the Yellowstone magma plume,

the tube through which molten
rock from the Earth's core

reaches the magma chamber
sitting on top of the plume.

Using similar data, geologists
have created this 3D

illustration of
the magma chamber

as it sits below the
Yellowstone caldera.

This is a three
dimensional image,

like a CAT scan or an
X-ray of the earth,

is giving us an image of what we
think is the magma system that

drives Yellowstone.

NARRATOR: This u-shaped
chamber is thought

to contain more than 300 cubic
miles of partially molten rock,

a hundred times larger than
Pinatubo's magma chamber,

and is just five miles
below the surface.

More importantly, the area
of the most dramatic uplift

spotted by the
satellites is directly

above a peak of the chamber.

This suggests the magma chamber
is expanding, pushing up

against the earth's
surface at this peak.

The other area of striking
ground deformation

is near the Norris Geyser basin,
the hottest and most unstable

thermal basin in the park.

JACOB LOWENSTERN:
Norris Geyser basin

is one of the most dynamic
of the hyperthermal areas

at Yellowstone.

It's always changing.

We're always noticing new
things that are happening.

NARRATOR: Just a few years
ago, satellite images

showed Yellowstone's
greatest rise in this area.

Recently, however, it's
reversed its direction

and is now subsiding.

JACOB LOWENSTERN: It's not
actually within the Yellowstone

caldera, yet it's one of
the highest temperature

thermal areas in the park.

And it is possible that
there is some magma extending

to the north
beneath that region.

NARRATOR: The source of
the basin's volatility

could be magma or
another key component

to volcanic activity,
earthquakes.

ROBERT SMITH: The
earthquakes are essentially

the heartbeat of the system.

They are an integral part
of the active, if you wish,

mountain building and
volcanism of Yellowstone.

NARRATOR: Like smoke and fire,
volcanoes and earthquakes

go hand in hand.

The pressure from
the magma which

can explode into a volcano also
forces the ground to shift,

causing earthquakes.

They can be the telltale signs
of an impending eruption.

The two main precursors to a
volcanic eruption, seismicity

and ground deformation,
are very carefully

monitored in Yellowstone.

NARRATOR: In this
computer model,

each red represents
an earthquake.

Typically, hundreds
of earthquakes

are detected across
the park each year.

In recent years, the
greatest earthquake activity

has been centered under
two areas of the park.

You can see we
have earthquakes that

are concentrated on the
north side of Yellowstone

coming down through
the park, and then

extending on the east side of
the Teton fault right here.

NARRATOR: What
concerns geologists

is when a center of
earthquake activity

overlaps an area of
shifting terrain.

At the Norris Geyser basin, that
seems to be what's happening.

There are dozens of
fault lines at this spot.

That's very critical
because if magma is starting

to move up, we would
expect to see a bulging

in an area and
associated earthquakes

as the ground starts to crack.

NARRATOR: The fear is faults
that make up the earthquake

zone could crack under
pressure from the magma below,

releasing an eruption.

Geologists are also watching
the park's geysers, hot springs,

and mud pots, looking for
drastic changes in temperatures

and chemical content,
anything that might indicate

a major movement of magma.

At the moment,
geologists do not believe

an eruption is imminent.

But if the water
temperatures were to rise,

the ground begin to swell,
or there were an increase

in earthquake activity,
another Yellowstone eruption

could be building.

I think that we are smart
enough as geoscientists now

that we would
probably have weeks

to perhaps months of
indicators before anything

like that would occur.

NARRATOR: However,
predicting the precise timing

of an eruption is
far from simple.

Scientists have been
fooled in the past.

MICHAEL RAMPINO: We've
seen it in Yellowstone.

There is a bulging.

There's vibrations.

There's increased seismicity.

There's all the things
one would expect and go,

oh, uh oh, we're in trouble.

And then-- nothing.

NARRATOR: Therein
lies the problem.

All we can do is
monitor the volcano,

but it may not be enough to
predict a possible eruption.

Mount St. Helens was the most
scrutinized volcano in history,

and it exploded before
the area could be cleared,

killing 56 people.

At Yellowstone, despite
its remote location,

a giant eruption could put
thousands of lives at risk.

Remember, we have maybe
100,000 people per night

staying in the Yellowstone-Teton
system in the summer.

This is equivalent to a
community of a modern US

city that are compacted
into this zone

of potential eruption, so
the exposure is rather high.

NARRATOR: At Yellowstone, we may
be on the edge of a precipice,

and the question is not if it
will erupt, but how and when.

There's nothing you
can do about a volcano.

If it's going to go off,
it's going to go off,

and the effects on civilization
are going to be drastic.

NARRATOR: We may not be
able to prevent an eruption,

but when the molten rock begins
to move up toward the surface,

will all the scientific
data warn us in time?

Now, using historical
records, scientific models,

and the latest in
computer technology,

you will witness
the devastation that

follows when the giant
volcano at Yellowstone erupts.

The force of the earth's
gravity is weaker at Yellowstone

due to the hot water and
molten rock below the surface.

For 70,000 years, the
Yellowstone volcano

has remained quiet.

But sooner or later,
its magma chamber

will slowly fill with millions
of tons of molten rock.

Gas pressures will push
up toward the surface,

bringing the volcano
to the breaking point.

This is one of the
rules of geology--

if it happened in
the past, it'll

happen again in the future.

We know there's going to be
super eruptions, and probably

one at Yellowstone,
and it's going

to have catastrophic effects.

NARRATOR: Now, using computer
models and the latest

scientific information,
you will experience

what would happen if the
largest volcano in North America

were to erupt.

When that eruption
occurs, there

is no doubt whatsoever
that parts of the northwest

of the United States will be
completely and comprehensively

devastated.

It'll just be over.

It'll be toast.

It'll be finished.

NARRATOR: The first indications
of a Yellowstone eruption

will be rumblings heard
underfoot as dozens of smaller

earthquakes begin.

The ground begins to rise from
the pressure of the expanding

hot waters, gases,
and surging magma.

The templors grow in strength,
spreading across the entire rim

of the caldera.

All the tourists have to
be cleared from the park.

Officials send out
warnings to towns

within a 100 mile radius, the
danger zone of a Yellowstone

super eruption.

The cities of Bozeman,
Montana and Cody,

Wyoming prepare for the worst.

Throughout the park,
new cracks in the ground

release huge geysers, spouting
superheated water hundreds

of feet into the air.

The earthquake
shaking itself will

create fractures and cracks,
allowing more material

to come out.

NARRATOR: The last of the
tourists and park personnel

must rush to leave the park,
trying to reach a safe distance

some 100 miles away before
the caldera lets go.

They may not have enough time.

Lava first appears, oozing
out of cracks in the surface.

Then, steam and ash explode
hundreds of feet into the air.

But instead of this
relieving the pressure,

it pushes the volcano
over the edge.

JACOB LOWENSTERN: The magma
contains a lot of gas,

and if you were able to
depressurize the system

rapidly, then the magma will
lose its gas explosively,

and you can have a very,
very large eruption.

NARRATOR: From five
miles below the surface,

molten rock heated to 1,200
degrees bursts into the air.

It begins to erupt, and you
see these flows coming out

sideways.

And there's nowhere to go.

NARRATOR: Like a
hurricane of ash,

pyroclastic flows rip along the
ground at 100 miles per hour.

For those who left the park
within the past half hour,

their luck has run out.

50 miles away, the 30,000
residents of Bozeman, Montana

watch in horror as the plume
of ash and rock reaches

into the sky.

If they know anything
about Yellowstone's past,

they'll know they
have little time

before their city is devastated.

MICHAEL RAMPINO: The
pyroclastic flows

may go out as far as 50 to 100
miles away from the volcano.

And so you'd see the pyroclastic
flows coming across ridge,

after ridge, after
ridge, and then,

finally, hitting where you are.

So locally, regionally,
it's absolutely devastating.

Everything would be killed.

NARRATOR: The sky begins
to darken as the ash cloud

obscures the afternoon sun.

The material is going
to explode violently

to the surface, and the
material's are coming out

at supersonic velocities.

And the finer materials go
50,000, 60,000, 80,000 feet

into the atmosphere.

NARRATOR: Then,
a second eruption

begins on the other side of
the caldera, then another.

It is no longer a simple
volcanic eruption.

Like it did hundreds of
thousands of years ago,

Yellowstone builds into the
largest eruption known to man.

The giant cauldron of
magma spews a million tons

of melted rock thousands
of feet into the air

as several volcanoes
continue to erupt.

Wave after wave of
burning ash and debris

destroy everything
in their paths.

With so little warning, nearly
400,000 people are at risk,

and it gets worse.

ROBERT SMITH:
Material falls back

onto the surface of
the earth, and so you

get ashes that are maybe
10, 20, 30 feet deep

around Yellowstone.

NARRATOR: A brilliant
summer afternoon

begins to look like a
blustery, snowy night.

The weight of the falling
ash collapses roofs

across the states of
Wyoming, Idaho, and Utah,

killing thousands, while a cloud
of lighter ash a thousand times

larger than the one
produced by Mount St. Helens

drifts eastward with the wind.

JACOB LOWENSTERN:
There's so much ash

put into the atmosphere, and
it gets distributed so globally

that it would cause
disruption to air traffic

not just near the scene
of the eruption, but,

really, globally for
a period of time.

The ash goes in the jet engine
and becomes ceramic and coats

the jet engine, and there have
been horrifying descriptions

of airplanes just losing
their power and diving

while the pilots try to
figure out what to do to start

the engines again.

NARRATOR: Air travel
grinds to a halt

as the ash cloud reaches
the upper atmosphere,

and then the deadliest part
of the Yellowstone eruption

begins.

MICHAEL RAMPINO:
There's lots of ways

you can die in a
pyroclastic eruption,

and one way is to
inhale the stuff

and inhale these
sharp pieces of glass.

They attack the lungs.

They attack the bones.

They kill you from the inside.

NARRATOR: Across
the country, masks

are supplied to protect
people against the ash,

but farm animals
have no protection.

Within weeks, vast numbers
of the country's livestock

die, like the animals that
roamed the Nebraska plains

12 million years before.

And volcanic ash covers much
of the Midwest farmland.

MICHAEL RAMPINO: They can't
grow anything in that ash.

Fresh volcanic ash is
sterile, like Mount St. Helens

just after the eruption.

And so it wipes
out the breadbasket

of the world,
breadbasket of Canada,

breadbasket of
the United States.

NARRATOR: And the effects
could last for years.

Recovery is going
to be a long process.

So where does food come
from in the meantime?

I don't know.

NARRATOR: Millions of people
could die from starvation

related directly to the
ashfall in America's Midwest.

Countless more would suffer
as the ash cloud drifts

across the globe, dramatically
changing our climate.

JACOB LOWENSTERN:
It's quite likely

that the climatic effects would
be much worse than humans had

experienced in the
last couple years.

NARRATOR: The Toba eruption
suggests that ash particles

would remain in the
atmosphere for six years,

radically cooling the planet.

It could mean snow in
June, frost in August,

and the killing off of
crops for years to come.

Imagine six years
without a growing season.

What does that mean?

I foresee a very
difficult period of time

when civilization would really
be strained at the roots.

This would be the most severe
condition that human beings

have ever met.

NARRATOR: It may not happen
for thousands of years,

but one day, history
will repeat itself.

The slumber of the
Yellowstone caldera will end,

and the planet will face
potential catastrophe.

Hopefully, by then we'll
be prepared, but if not,

it could be one of nature's
greatest mega disasters.

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