Original subtitles

Volcanoes are sleeping giants.

Woe betide us should they awake.

Millions of people live in their shadows

and very close to a looming catastrophe.

But even giants far away and long forgotten

can suddenly come alive.

Looking at history, we come to understand

that active volcanoes also need to be

reckoned with in the future.

Volcanologists, climate researchers, geologists.

They all want to learn from previous catastrophes

in order to save lives in the future.

In a way, they're like beauty and the beast.

Can we protect ourselves from this danger?

We can't always predict these events.

People will die.

The Ilopango Lake in El Salvador.

Few know that this huge lake was created

by the eruption of a volcano.

Archaeologist Payson Sheets from the University of Colorado

is eager to find out how civilizations

can prepare for large volcanic eruptions.

In order to do that, he is going to conduct research

on a dormant giant, a volcano right directly beneath him.

1,500 years ago, this was, much as it appears now,

beautiful, quiet,

but the magma pushed up through a vent

caused a colossal steam explosion

and volcanic ash blasted all over the landscape

and changed El Salvador from a lush, tropical paradise

it really was -

to a desert, a white desert, overnight.

Could the volcano erupt again today?

Let's go.

Its crater is 230 meters deep.

That is twice the height of the Statue of Liberty.

Its sides are steep and are strewn with hot springs.

There are indicators that new magma

continues to rise to the surface.

In some spots, it heats up the water to 70 degrees.

The volcano is still active.

The majority of dormant giants remain invisible,

sometimes for so long that they fall into oblivion.

How do people react in view

of the possible sudden catastrophe?

Payson Sheets delves deep into the past

to answer this question.

The traces of this past catastrophe

can also tell us what the future holds.

It is the quest for the power of the sleeping giants.

Robert Dull from the University of Texas in Austin

has researched the scope of the last great eruption.

There is a very large magma chamber

that sits under Lake Ilopango

and one of the wonderful things about a caldera lake

is that, unlike the more conical strata volcanoes

that we are used to seeing,

the magma chamber down below,

the lake itself is showing really almost

the entire size of the magma chamber.

I expect that an eruption will happen from Ilopango

at some time in the future.

It's happened over and over again in the past

and it's likely to happen again.

This is the place you need to research

if you want to know how civilizations react to the threat,

because El Salvador hasn't just been

destroyed several times by volcanoes,

the area has also been populated since millennia.

Joya de Ceren is located 35 kilometers from the Ilopango.

The small Mayan town provides important clues

as to how people have led their lives in the face of danger.

For one thing, the village isn't located

under the ash layer of the Ilopango.

It is actually constructed on top of it.

The results of his excavations here

made Payson Sheets believe to have found

what a life with a sleeping giant has been like

up until today.

More than 1,000 years ago,

only a few hundred people lived in Ceren.

Their village was destroyed by a volcanic eruption.

If you dig here, you dig through several ash layers

that were produced by the sleeping giants.

Volcanoes in a place like this

have some very beneficial aspects

and some very detrimental aspects.

The beneficial ones are creating rain up high

and volcanic ash weathering into very fertile soil.

In this case, the soils recovered, people came in,

started this small community of Ceren

200, maybe 300 people.

But look what they did, they built this gorgeous,

delicate, very religious building for a diviner.

The shaman is an intermediary

between the people and their environment.

She is asking for good harvests

and safety from nature's perils.

The shaman here can handle

these everyday kinds of anxieties,

but when the eruption occurred,

she could not do anything to help.

The problem is that if you're standing

this far away from me shouting, you cannot hear.

The sound from the steam emissions

from the very beginning of the eruption is way too loud.

It's the loudest sound they ever heard in their lives.

And they inhaled that cloud

that is following them, catches up to them.

It coats the inside of their lungs with volcanic ash

and they have about a minute or a minute and a half

to keep living.

No more oxygen gets to them.

It is a very painful death.

This story illustrates

feeling safe is the biggest danger.

But Payson Sheets believes that the giant's power

reaches far beyond its ash.

In Mexico, 12,000 kilometers away,

there is a mysterious place.

Whereas villages have been built

on the ashes of the Ilopango in very close vicinity,

life here seems to have come to a halt forever.

Today, the city in Mexico's high plateau

is called Teotihuacan,

the place where humans become gods.

The only thing that this high culture left behind are ruins,

but the most monumental on the American continent at that.

The pyramid here measures 65 meters.

It is the third tallest in the world.

This huge city is considered to be the precursor

of many of Mexico's civilizations,

but its downfall remains a mystery.

Above ground, no stone is left unturned.

So the secret of the former metropolis must lie elsewhere.

The exploration of Teotihuacan is difficult.

There are neither decipherable scripts nor other accounts,

nothing that explains its downfall.

Archaeologist Sergio Gomez is hoping to find out more

about the former high culture's fate

14 meters below one of the pyramids.

He follows a tunnel that the inhabitants constructed

under the Temple of the Feathered Snake,

the pyramid devoted to one of their most important gods.

It's a rare find.

In 2003, Gomez discovered a shaft

100 meters away from the pyramid center.

Since then, he's been trying to advance

further into the tunnel.

Camera robots give the researchers a first impression

of what awaits them on the inside of the shaft.

Not only did the inhabitants dig this tunnel,

but they also sealed it with tons of earth

after its construction.

Without pack animals and wagons,

they put a tremendous effort into hiding a construction

that was supposed to remain hidden forever.

After a few attempts, the robot succeeds

and advances into the first segment of the tunnel.

The images show that the tunnel

wasn't constructed to serve an earthly use.

It is part of a type of underworld

that existed underneath the bustling city.

Its purpose, however, still puzzles scientists.

At the moment, we're still working on the tunnel

to better understand their system of government.

One of the main theses that I set up

is that we will find the grave or the human remains

of those that stood in close relation to the government

or political system of Teotihuacan.

Meanwhile, the team has uncovered

several meters of the tunnel.

An imperial grave, however, has not yet been discovered.

But the tunnel contains countless clues.

75,000 objects have been recovered

and they can be read like a book.

Caribbean conches, statues, masks, and sacrificial vessels.

Mysterious cultures with ornaments showing

a high level of craftsmanship.

The inhabitants must have been in contact

with several different cultures.

But few of the found objects were of practical use.

The most bizarre find: Ritualistic knives made of glass

and a piece of human skin.

Teotihuacan was the most important

and influential city of its time.

In between 100 and 500 CE it was the center

of a huge, complex empire

that was governed from Teotihuacan.

Furthermore, Teotihuacan was, symbolically speaking,

the most important holy city that existed,

that had ever been constructed until then.

Teotihuacan is located in central Mexico,

just 45 kilometers from the capital.

It is known to have served as a model

for the construction of Mexico City.

Today, over 20,000,000 people live

in the environs of the city,

one of the world's largest.

It is the economic, cultural,

and social epicenter of the country,

and it continues to grow.

Especially in its wealthy center,

one can easily forget the danger of a volcanic eruption.

It's a normal day like in any other megalopolis.

Everything seems to be more important

than a preparation for a disaster situation.

Modern symbols of wealth and power rule the skyline,

even though both Teotihuacan and Mexico City

are surrounded by volcanoes.

The pyramids and towers of glass rest on troubled ground.

Mexico is in the hands of the sleeping giants.

Craters rise up everywhere.

In some areas, they protrude out of a sea of houses.

This volcano named Xico is considered to be dormant,

but magma is seething underneath it.

It can find its way to the surface at any given moment.

This is the largest daisy chain of volcanoes on the planet.

The country lies on the so-called Pacific Ring of Fire,

a fissure line of the tectonic plates

around the Pacific Ocean.

Nowhere are there more volcanoes,

and there are 40 of them in Mexico alone.

Only 50 kilometers from Mexico City,

one of the most dangerous volcanoes,

the Popocatépetl, lies dormant.

Its active signs are constantly monitored.

Seismic waves, elevations of the ground, gases.

It became active again in the 1990s.

Currently, a so-called lava dome seals its shaft.

Should the volcano stir,

the instruments will raise the alarm.

Ramon Espinasa is the vice director

of the Popocatépetl Observatory.

He tries to foresee the time of a future eruption.

Once lava is spewed out, it collects at first.

Because it's very slow-flowing lava,

it doesn't flow downhill but stays in the area

of the volcano's opening instead,

forming a hill in the exact shape of a dome.

This dome seals the shaft and prevents

not only gases from leaking but also the release of energy.

That's why this energy is then collected underneath it

until it reaches a sufficient amount to explode

and to catapult the dome into the air.

Any movement of the volcano

could be the start of a large eruption.

In 2000, a big eruption announces itself.

The formerly peaceful, sleeping neighbor awakens

and instantly becomes a threat.

The residents of the surrounding villages are evacuated,

even against their own will.

But El Popo quiets down again,

only to awaken shortly thereafter.

The constant to and fro deadens the residents' fear.

Once the alarm sounds again,

many refuse to leave their houses.

Psychologist Esperanza Vazquez is a researcher

for the Mexican Ministry of Health, among others.

It is her goal to make the population

aware of the seriousness of the warnings

given by geologists.

To this end, she examines the relationship of the residents

to their mountain.

They look at it and say "Oh, he's happy.

"He's coughing."

And even if they're not thinking this way,

the volcano still plays a central role in their lives

and some studies that I've conducted show

that the people living here

see the volcano more as a legend,

as a part of the landscape.

Their image is a lot more positive

than that of scientists from abroad,

who see it as a threat from an objective point of view.

The locals see it as a part of their identity.

The volcano is like a relative to them.

How do the residents

in the immediate surrounding area of the volcano

cope with the threat of an eruption?

Is the threat even taken seriously?

Those are questions that Esperanza Vazquez

wants to find answers to.

They are important to determine the best way

to communicate with the people

so they can be evacuated in the event of an emergency.

The psychologist especially wants to communicate

with the new generation.

Shut off the water, turn off the gas,

and switch off all electrical devices,

and put on protective glasses and a face mask

so I won't breathe in any ashes that could hurt me.

I think it's better to be close to an active volcano.

A dormant one can also erupt at any time,

but with an active one, at least you know about it

and you can prepare better for it.

People all over Mexico

are aware of the volcano's untamed powers.

Just 230 kilometers from the capital,

there is a village church embedded in lava.

Its history shows just how fragile

the Earth's crust in Mexico really is.

In February 1943, in the middle of a corn field,

the ground starts to rise and then burst.

A new volcano is formed right in front

of the eyes of the farmers.

Within two days, its constant eruptions

produce so much lava

that it rises up to a height of 50 meters.

A year later, it is 336 meters high.

The lava destroys everything in its path,

except for the church.

10 years later, the volcano falls silent,

but only after a very long eruption.

These past eruptions help to understand

recurring events in the course of Mexico's history.

In the fourth century, for example,

the shaft of the Xitle covered the world in ash

with a single long-lasting eruption

without a previous warning.

Eruptions such as these can reach gigantic dimensions.

The Xitle lets an area of 70 square kilometers

disappear under its ash and lava.

The city of Cuicuilco is completely destroyed.

The residents have to leave their land,

taking only meager belongings that can be saved.

Only the pyramid defies destruction.

Today, it is located in the middle of Mexico City

in between the university and residential areas.

Entire districts of the modern metropolis

were constructed on top of lava fields.

Where did all these people go back then?

Sergio Gomez has traced the path of the refugees

and came to a surprising conclusion.

What is remarkable is that all of them fled

into the same direction.

Their path leads directly to Teotihuacan.

This has widespread consequences.

The eruption of the Xitle volcano

has dramatically changed the history of the Mexican basin.

The social and economic history of both places,

Cuicuilco and the rising city of Teotihuacan,

was rewritten.

Teotihuacan has therefore never had any rivals,

and could establish a wide-reaching network

of economic and social connections.

It was able to spread its rule

of the entire Mesoamerican region.

Several volcanic eruptions

are the cause of mass migrations.

With the arrival of the refugees,

Teotihuacan gains importance

as more and more people are drawn to the city.

But what makes the city so attractive?

One of the reasons is its religious system.

In Teotihuacan, the people make a pact with the gods.

The residents carry the occult to an extreme,

as if they wanted to confront the force of nature

with everything humanly possible.

The priests don't even shy away from human sacrifice,

meant to protect the city from catastrophes.

But the idea that nature can be

kept under control by performing rituals

will soon be proven wrong.

Even today, the danger is far from over.

The giant can awaken at any moment.

How do you live with a dangerous volcano close by?

How do you cope with its constant threat?

No one trusts the official institutions anymore.

Too often, they warn the population of an eruption

that didn't happen in the end.

Therefore, many turn to ancient knowledge.

For shaman Epifanio Alonso, faith is the only way to cope

with living in the volcano's shadows.

We always trust in God first, always.

The volcano is the place to ask for what we need.

It is the place of the descent of God's spirit.

Here, we pray to receive everything we need to live,

everything we need.

Volcanoes represent the primal forces of nature.

Their power reaches beyond human control.

That is why they continue to be seen as home

of holy beings until today.

For me, it is a church,

a church into which you can't just look into.

I'm telling you this because in my dreams,

I have seen what it looks like from inside.

That's how it is.

And we climb up there to pray for enough food,

because the volcano protects the seed.

Even today, people try

to control the Popocatépetl by performing rituals.

Prayers and offerings are seen as guarantors

for security and prosperity.

And there is indeed a bit of truth in this belief,

because earth of volcanic origin

is very loose and full of minerals.

These are ideal conditions for plants

and thereby for agriculture

as well as livestock farming.

In the area surrounding the volcano,

a few centimeters underneath the soil

lies the ash of its eruptions.

As soon as the giant sleeps,

the ash turns into the most fertile soil on the planet,

but the price is high.

The Popocatépetl has catapulted stones all the way to here,

several kilometers away.

In case of a big eruption,

there would be an ash column

reaching all the way into the stratosphere,

15, 20 kilometers high.

All of this material would then fall back into itself

and cause pyroclastic flows

that would cascade down the sides of the volcano

towards the surrounding villages.

These pyroclastic flows

are the biggest and most treacherous

dangers of a volcano,

barely noticeable at first because they are so quiet.

But they soon pick up speed and spew over

everything in their way

at up to 400 kilometers per hour.

It is highly dangerous to conduct research on them.

In the 1970s, Katia and Maurice Krafft

were real celebrities in the geologist scene.

Risking their lives, they got closer

and closer to the crater.

Even today, this is still the only way

to learn more about volcanoes.

How exactly do pyroclastic flows behave?

What makes them so dangerous?

In 1991, the Unzen in Japan shows increased activity.

It is one of the most dangerous volcanoes in the country.

The Kraffts are just a few meters

above the valley floor on the hillside

when the pyroclastic flow reaches them.

Both lose their lives.

At the Smithsonian Institute in Washington,

one scientist has managed to create

pyroclastic flows in the laboratory

at a safe distance.

Benjamin Andrews didn't have to risk his life for this.

He creates artificial ash clouds on a smaller scale.

They behave just like real flows but they're a lot smaller.

This is just a mineral talc,

and it's been smashed and sorted

so that it's all the same size.

So it really is like using baby powder without the scent,

except that we buy this baby powder in 40 kilogram drums

instead of 800 gram bottles.

The size of the particles, their weight,

everything is precisely calculated.

Here in the laboratory, the scientist can safely

examine several scenarios.

He creates obstacles on a miniature scale,

like small mountains.

What makes the flow so dangerous in real life?

Pyroclastic flows are very dangerous

because they move very fast,

they're very thick, and they're very hot.

And these currents, they look fluffy

but they're not fluffy at all.

Instead, they're a very fast-moving mixture

of ash, and rocks, and pumice,

and all of this has the effect of destroying

pretty much anything and everything in its path.

A laser light makes visible

the behavior of the flows.

If they are relatively cool,

they can easily overcome the obstacle.

Benjamin Andrews heats up the ash using a toaster.

He wants to know whether

extremely hot ash behaves differently.

And indeed, once a hot pyroclastic stream hits an obstacle,

it can't overcome it.

Instead, ash and gases rise into the atmosphere.

One thing that our experiments here can do

is ultimately help develop better or more informed risk maps

based upon how far do we think pyroclastic flows might go,

how might those pyroclastic flows interact with topography

or interact with a river valley.

The local authorities close to Popocatépetl

are trying to find safe ways out of the danger zone

using these investigations.

It's been 2,000 years since the last big eruption.

It would be negligent to forget about it.

On the contrary, the more time that has passed

since its last eruption,

the more likely a new one is to occur.

Tension increases with the mountain's every move.

Once the instruments sound the alarm,

20,000,000 people are in immediate danger.

CENAPRED to El Popo, CENAPRED to El Popo, do you read?

Smaller explosions and earthquakes like these

can always be the beginning of a larger eruption.

This is Popo calling CENAPRED.

I can read you loud and clear, over.

The preparations for an emergency are meticulous.

Nonetheless, it is almost impossible to evacuate

a city with millions of residents.

German volcanologist Claus Siebe has been

working in Mexico City for 20 years.

He is trying to determine the consequences of an eruption.

What would the ash do to the city?

Its dense population, location,

and the ailing infrastructure

would seal the city's fate.

Mexico City certainly is a special case

because it's a metropolis, a megacity

that isn't located next to a river or the ocean.

The city's sewer system is already quite strained.

A case like this would lead to plagues

and even bigger problems.

And the sewers aren't the only concern.

The ash can get anywhere.

It can contaminate the drinking water,

rupture the power supply through short circuits,

and impair car and air traffic by limiting visibility.

It is hard to believe that more and more people

want to move here.

But life with a fire-spitting giant

can also have its benefits,

benefits that were also valuable to Teotihuacan back then.

Volcanoes create fertile soil.

They seem to intensify the need for rites and culture.

The pact with the gods promises people a life and safety.

But for Teotihuacan, these are not the only advantages.

Imagine, it is the most successful civilization

that had ever existed in Mesoamerica

in political, and economic, and religious terms,

no doubt about it.

Just like Mexico City,

Teotihuacan lies on a high plateau, far away from the ocean.

Nevertheless, the residents have access to plenty of food.

There is prosperity, and not only in the upper class.

Soon, the city becomes larger than the ancient Rome.

At Teotihuacan, you have to imagine

a city of over 100,000 people, beautiful gridded streets

and residential compounds, apartment buildings,

and the agricultural system works very well.

Trade routes are all the way down

into what's now Guatemala, and Belize, and El Salvador,

all the way up into New Mexico.

Volcanoes supply the crude material

for the city's wealth.

The alleys are full of obsidian workshops.

The volcanic glass is used to create jewelry,

cult objects, and tools.

And Teotihuacan exports weapons to all of Central America,

one of the most important commodities of the time

that could be exchanged for food,

cosmetics, and luxury goods.

Obsidian is created when lava cools down so quickly

that it cannot form any crystals.

The volcanic glass has helped Teotihuacan

to become the first trade city in Central America.

We have proof of Teotihuacan presence in Guatemala,

Honduras, even in El Salvador,

places and people the city must have had

some sort of contact with.

Volcanoes let the city flourish.

Remarkably, its residents left shortly after

the eruption of the Ilopango in the 6th century.

Is this where the secret of the city's

downfall can be found?

1,200 kilometers away?

Payson Sheets is sure that the Ilopango

is responsible for the fall of Teotihuacan.

But after several centuries, it is hard to prove his theory.

Humans were also sacrificed here

to appease the giant, just like in the city.

Figurines of Christian saints that have been

brought up here by later generations

testify to this.

And yet, the danger seems to have been forgotten.

And people would like to believe in this area

that that's it, it won't erupt again.

Sorry.

Sorry, this is not a good place

for long-term land investment.

Over here you see 540, over here you see...

Robert Dull has managed

to date Ilopango's eruption.

This offers a decisive clue.

This is a massive amount of information

that you're putting together.

This is ice cores and tree rings.

Here's 1257, that's the Samalas event.

In a sense, in kind of a selfish

archaeological sense as a researcher,

I know that there are hundreds, literally hundreds,

of archaeological sites buried

by the volcanic ash from Ilopango.

They all date of course to the same timeframe.

Today, the villagers that were suffocated under the ash

are the only witnesses.

They reveal how massive the eruption of Ilopango was.

Judging by the measurements of the ash's dispersion,

it must have spewed out up to 160 megatons of sulfur.

Sulfuric acid clouds circle the globe for several years.

The climate is out of control.

That means that the eruption didn't only happen

in the time in question,

but that it was big enough to influence the climate

even in places very far away.

They got hit by this dramatic downturn in climate

that was both a long-term, more than a decade

of cold temperatures and drought.

Both of those caused in Teotihuacan

a failure of confidence in the system.

The city faces the consequences

of the largest volcanic eruption in 2,000 years.

For 500 years, the pact with the gods

and the omnipotence of the priests

have kept the volcano in check.

The human sacrifices seem to have silenced the volcanoes.

They had ensured rain, and with it,

fruitfulness and prosperity.

But suddenly, there is no more rain for years.

The gods seemed to have forgotten the holy city.

There was a fire that ran along the street of the dead

and burned the temples.

Early, people thought it was a huge fire

that ran through the city.

No, it was set.

The enraged residents set fire

to the symbols of the gods

that no longer provide them with shelter.

The city was largely abandoned

and it never regained that kind of political,

economic, religious power.

That was it.

History shows that even

highly developed civilizations

cannot oppose the force of volcanoes.

1,500 years after the catastrophe of the Ilopango,

in 2008, the Chaiten in southern Chile erupts,

almost without any prior warning.

Its eruption catches the population off guard,

and it can barely flee to safety.

Shortly after, the eruption column collapses

and pyroclastic flows gush down the sides of the mountain.

The Chaiten has proven how difficult it is

to predict a dangerous eruption.

For centuries, the volcano was considered to be dormant.

The city of Chaiten is completely destroyed.

Due to the destruction and the constant volcanic activity,

the government decides to abandon the place completely.

Villages and people within the radius of volcanoes

can be led to safety,

but the history of Teotihuacan indicates

that the giants pose a threat

that can even reach cities that are far away.

These are especially vulnerable.

In 2010, the eruption of Eyjafjallajökull

gives us an inkling of how vulnerable even modern

and technologically advanced societies can be today.

Exactly what volcanologists fear the most takes place.

Magma comes into contact with glacier ice.

The steam explosions rip apart the molten rock

into tiny ash particles.

Poisonous fluorine and ash spreads over the landscape.

500 people have to be evacuated from around the volcano.

The farmers that work the area are hit especially hard,

but the consequences spread further.

The wind continuously pushes the ash clouds

into higher air layers

and sends them across the North Sea

over to central Europe.

In April 2010, they reached Germany.

All air traffic is grounded.

Europe is at a standstill.

100,000 passengers are stranded

and cargo flights are canceled.

And yet, the eruption of the Eyjafjallajökull

isn't even the biggest one.

The volcano ejects only about 0.14 cubic kilometers

of material into the air.

The eruption of Mount St. Helens is 10 times bigger,

and the Ilopango's 100 times as big.

The eruption of a super volcano could release

more than 1,000 times that amount.

So, we cannot fathom,

I cannot fathom,

the enormity, the massive scale of an eruption

of Yellowstone should it occur again today.

This volcano is almost unrecognizable,

simply because of its enormous size.

The Yellowstone super volcano is one of the world's biggest.

It lies dormant in the middle

of the Rocky Mountains in Wyoming.

Henry Heasler is a geologist working

for the Yellowstone National Park.

He monitors the numerous geysers,

visible signs of the sleeping super giant.

Go ahead and pan it out towards...

This is the largest collection

of hot springs in existence.

3,000,000 visitors come to see them every year.

In a way, they're like beauty and the beast

at the same time.

They look gorgeous but you can have

above boiling temperature waters,

you can have acidic conditions, pH 1 and 2,

the pH of battery acids,

you can have dangerous geothermal gases in low areas.

So how do we choose where to safely put these boardwalks

so visitors can experience the sights, sounds, and smells

of a hydrothermal area safely?

It is invisible to the visitors,

but the American continent is pushing itself

very slowly over a huge magma bubble.

The tourists deem themselves in safety

while contemplating the natural spectacle

above the super volcano.

Every year, 2,000 small earthquakes

and recurring elevations of the ground

reveal that the giant is alive.

Only as recently as 2014,

the biggest seismic shock in 30 years hit the area,

thankfully without causing any serious damage.

No scientist can predict when the volcano will awaken again.

The only thing we can do is to monitor the giant.

One look into the Yellowstone's history shows

that the volcano has erupted several times.

These eruptions put out so much volcanic material

as a fine ash, it was jetting it out.

It wasn't a big explosion, it was jetting it out

much like when an apple pie starts to break

and you get steam coming out

that the ground then subsided.

Just a few kilometers underneath the surface,

magma eats its way through the Earth's crust

like a welding torch.

Only since 2015 do we know that the bubble

is incredibly large, 46,000 cubic kilometers.

The last eruption of the Yellowstone

was 630,000 year ago.

It destroyed everything within a radius of 100 kilometers.

Ash rains down even 1,500 kilometers away.

The rest of the world disappears into darkness

for over decades.

You got these big, dense populations.

Try to have them handle a big eruption?

They don't.

They become archaeologically important material, thank you.

But they did not do well at that time.

The cloud of the Yellowstone

could well introduce a new, small Ice Age.

Under a veil of ash and sulfur,

the tropical rainforests would freeze.

Supplying cities with over a million inhabitants

would become impossible to handle.

These huge eruptions are extremely rare.

They occur only once every 100,000 years.

However, the giants are still just asleep

and lure us into believing we are in safety

by overwhelming us with their beauty.