Original subtitles

Volcanoes are a spectacular display

of nature’s power,

with eruptions which are awesome to behold

yet utterly deadly.

These infernos of nature

can unleash cataclysmic destruction in their wake...

from explosive blasts capable of scorching vegetation

and landscape for kilometers...

That’s very deadly, very fast moving and that will--

You’ve got no chance to escape from it.

...to towering toxic ash clouds

able to rise tens of thousands of meters into the air

and kill animals and humans by suffocation.

And if you see an ash cloud rolling towards you,

you’ve probably not got time to escape.

Volcanic blasts are so powerful

they have even been known to change the world’s climate.

Since the 1500s, over a quarter of a million people

have been killed by volcanoes.

And since the millennium,

over 2000 have lost their lives.

It is estimated that volcanic eruptions result

in over a billion dollars

in global property damage annually.

The ruminative force of volcanoes can seem boundless,

yet these dragons of nature also provide great benefits.

These include the creation of extremely fertile soil,

essential for agriculture and farming communities,

as well as stunning landscapes.

These features have attracted human settlements

around volcanic regions throughout history.

But such close cohabitation

with one of nature’s deadliest forces comes at a price.

Suddenly there was a blanket of dark ash,

came down and covered me.

It was so dark

that I just couldn’t see, I couldn’t breathe.

With fascinating expert insights

and firsthand accounts from survivors,

in this episode, we will be looking at volcanoes

and eruptions across different parts of the world,

including the deadly disasters on Mount Sinabung in Indonesia,

Mount Etna in Italy

and Mount Nyiragongo

in the Democratic Republic of Congo.

Volcanoes are vents

on the surface of a planet or moon

from which extremely hot materials

such as molten rock and hot gases

escape from the interior, causing an eruption.

A volcano is a site where there is molten rock

from within the earth that rises towards the surface.

Now, the molten rock can leak out

and give you lava flows, and molten rock can explode

and give you an explosive eruption,

or the molten rock can interact with steam

and not actually reach the surface itself

but give you a steam-driven eruption.

So anywhere where stuff from inside the earth

gets forced out onto the surface usually builds a mountain,

sometimes blasts a hole.

But the term "volcano"

doesn’t only refer to the vents from which hot lava erupts.

It also designates the massive landforms

that have emerged over time

as a result of volcanic activity.

These mountains, birthed from the rocks, ash

and other solidified volcanic debris around the volcano vent,

grow into towering peaks and slopes.

The resulting volcanoes are classified

according to their shape and size.

Most significantly,

they are classified according to their eruptive patterns,

a feature that plays a significant role

in volcano monitoring.

There are a number of ways

of categorizing different types of volcanoes.

So we can think of a volcano as a very morphological thing.

So the shape of a volcano.

The picture-postcard volcano is the one which is cone shaped,

the Mount Fuji-style volcano.

And then we get our more classical

shield-type volcanoes, or upturned dishes.

And we get variations of that in between.

So a volcano is really anywhere on the surface

that we see the product of volcanic activity.

And that volcanic activity is the result

of the generation of heat at depth

and the rising of molten magma to the surface.

And eventually we see that erupted product,

and that creates the fantastic shapes and activity

that we see on the surface today.

One of the most crucial parts of volcano classification

is assigning one of three statuses:

Active, dormant or extinct.

If a volcano is labeled as active,

it is currently erupting

or exhibiting signs of a foreseeable eruption.

If it is described as extinct,

it is not showing any activity and probably never will.

A dormant volcano is one that hasn’t erupted

for a significant amount of time,

although that may change in the near or far future.

However, just because a volcano is labeled as dormant

doesn’t mean it is necessarily any safer

than its active counterpart.

Mount Sinabung in Indonesia

was a volcano that, right up to 2010,

had not erupted for 400 years and was labeled as dormant.

But since then, the mount has experienced

a series of deadly eruptions

that have taken numerous lives and left thousands displaced.

The 8070-foot Mount Sinabung

on the Indonesian island of Sumatra

is home to more than 150,000 people.

The communities living along the volcano’s slope

take advantage of the fertile soil conditions

to grow a range of crops and produce.

The mount has been a staple and stable feature

on their landscape for centuries,

and they are dependent on it for their livelihoods.

But in 2010, all that rapidly changed

when the volcano erupted,

killing two people and displacing 30,000 more.

This sudden reanimation came as a complete surprise.

And according to experts,

Mount Sinabung had been monitored less

than its more active counterparts.

But the violent eruptions

that would ensue in 2014 and 2015

would cement the status of Sinabung as an active volcano

and forever change the lives of the inhabitants

who had made their home around it

for so many generations.

On the 1st of February, 2014,

the mount erupted again,

spewing out a plume of hot ash, gas and rocks

that reached up to 3000 meters into the sky.

The deadly blast killed at least 14 people,

including three schoolchildren and a teacher.

The deaths were caused

by fast-moving, toxic, pyroclastic ash clouds,

which engulfed surrounding villages.

These deadly clouds, termed pyroclastic flows,

made the eruption of Mount Sinabung

particularly violent.

Pyroclastic flows are the most dangerous and deadly elements

in an explosive volcanic blast.

Capable of moving at speeds of up to 720 kilometers per hour

and at temperatures known to reach 700 degrees,

they incinerate everything in their path.

It was a pyroclastic flow

that destroyed the Roman city of Pompeii in A.D. 79

and which claimed nearly 30,000 lives

on the Caribbean island of Martinique in 1902.

A pyroclastic flow is an avalanche

of lava blocks and volcanic ash,

finely fragmented volcanic material and volcanic gases

that cascade down the side of a volcano

like an avalanche does, like a snow avalanche does almost.

It’s also accompanied by a big sort of turbulent ash cloud

that rolls over the top of the dense basal avalanche

at the base of the flow.

So when you’re looking at these pyroclastic flows

from a distance, hopefully,

you see these sort of boiling ash clouds.

The bit that you don’t see is at the base of these currents,

sort of thick accumulations of coarse material

that can be very destructive.

They can burn people that get trapped in them,

they can destroy houses and infrastructure

because there’s a lot of coarse material in them as well.

So they essentially just bulldoze buildings over.

And they can bury buildings and towns as well.

It’s hot and it’s fast-moving,

you know, moving at 80, 90 kilometers an hour.

You can’t get out of the way.

And if you’re caught in a blast of hot ash and hot air,

you basically burn to death.

The ferocity and scorching heat of these pyroclastic flows

meant that rescue workers had to wait

and could not get close to Mount Sinabung immediately.

When they were finally able to approach the volcanic peaks,

they were faced with bodies buried deep in ash.

The disaster had a severe effect on the economy

as farmers lost their crops,

resulting in increased food prices.

Sadly, this would not be

the only volcanic disaster

to bring the region to its knees.

In June 2015,

just a year after the deadly eruption,

the Mount Sinabung volcano exploded once again.

A series of violent eruptions

lasting over the course of a few days

rocked the region.

On the first day,

the volcano erupted three times

in only a few hours.

Volcanic ash blanketed parts of Medan,

the provincial capital of North Sumatra,

about 50 kilometers from the volcano.

Residents were forced to wear masks

as winds carried smoke towards the city.

Authorities raised the alert status of Mount Sinabung

to the highest level.

Sinabung spewed out rocks and hot gas

over a distance of three kilometers incessantly.

Dense ash that was up to two millimeters thick

covered roads and homes located 15 kilometers away.

Eyewitnesses described an almost apocalyptic scene

of a dark cloud of smoke covering the entire sun.

Up to 28 pyroclastic flows were observed in one day.

The Center for Volcanology and Geological Hazard Mitigation

declared all areas within a minimum radius

of three kilometers from the summit of Mount Sinabung

a danger zone.

As a response to the severity of the situation,

authorities initiated the immediate evacuation

of the region.

Eyewitnesses described scenes

of several thousands of people,

including women with infants in slings,

transported down the mountain in police trucks.

Others made their way down

the charred slopes on motorcycles

with faces smothered in ash.

At least 10,000 people were evacuated.

Many were housed in temporary shelters

already under pressure due to the 20,000 people

already displaced from the volcanic eruption

of the previous year.

These refugee camps faced huge humanitarian pressures,

with urgent need for beddings,

toiletries, clothing, food, water tanks

and psychologists for trauma healing.

However, many of the villagers on Mount Sinabung

were reluctant to abandon the fertile soil

of the volcanic slopes which provides their livelihoods.

The volcano slope had been a key economic source,

helping the community grow diverse cash crops

such as chilies, oranges, cocoa and coffee.

Some people have no choice about living near volcanoes.

If you’re in a part of the world

where you’ve got subduction going on,

one plate going below another,

there’s going to be a line of volcanoes.

And volcanic land is often quite fertile

because you’re bringing fresh minerals to the surface.

So when it’s mature enough to start growing crops on,

you can get a good yield.

So volcanic land is,

can be quite good for farming,

but it comes with the risk that there’ll be another eruption.

For days,

authorities had pleaded with villagers

in the main danger zone to evacuate.

But according to the local disaster mitigation agency,

only 10,000 of about 33,000 people

living within the danger zone had moved a safe distance away

into tent camps or government buildings.

Luckily, unlike in 2014,

no injuries were recorded from the disaster.

But the cost and toll of this latest volcanic event,

following so quickly on the heels

of the previous year’s eruption,

was a serious blow for a community

already on its knees.

So, what exactly triggered these explosive eruptions

on a volcano that had stood dormant

for the past four centuries?

The answer seems to lie in the location itself

of Mount Sinabung on the Ring of Fire.

The Ring of Fire is essentially a geographical feature

whereby you have lots of different active volcanoes

in a very ring-shaped pattern.

Indonesia is positioned on the Ring of Fire,

an arc of fault lines in the Pacific Ocean

that frequently experiences volcanic activity.

Mount Sinabung is among about the 130 active volcanoes

in the country.

Most volcanoes are in seismically active

parts of the world

because the process that produces earthquakes

is often the same process

that causes molten rock to be generated.

The formation of magma is deeper down

as the rocks are dragged into the earth

and they encounter conditions which cause melting to occur.

Or they release seawater into the rocks above,

and that melts them.

The melt generation process

is a slow, ongoing process

and you need a large amount of molten rock magma

to approach the surface to give you a volcanic eruption.

The magma rising towards the surface under a volcano

doesn’t move smoothly.

It can vibrate the rock as it moves,

so you get volcanic earthquakes as well,

tiny earth tremors which, if it’s close to the surface,

sometimes local people can feel.

We can certainly detect it instrumentally.

So you look for these volcanic earthquakes

as the rock fractures or the magma moves

or the gas moves through the rock, vibrating it,

and if those signals get closer to the surface,

that’s a very good warning sign

that an eruption might be imminent.

So volcanoes are often seismically,

earth-tremorly alive before anything starts erupting.

And that’s a good sign that something’s happening.

White Island is a volcano

situated in the Bay of Plenty in New Zealand.

Most of the volcanic edifice is submerged underwater,

but the main crater is above sea level,

jutting out majestically in the bay.

It is one of the most active volcanoes in New Zealand

and has seen multiple eruptions between 1998 and 2001.

However, this hasn’t deterred the booming tourism industry

that had sprung up around it.

Being at a volcano

is one of the most awe-inspiring things you can do.

Being at an erupting volcano,

one which is possible to see the activity glowing at night,

for example, is just simply awe-inspiring.

It’s a bit of a rush as you’re up there

watching this activity progress through time.

The privately owned island was a major tourist destination

with boat tours to the volcanic land mass happening daily.

As part of these expeditions,

tourists could go to the island

and actually walk inside

the main active volcano’s crater.

However, with popular routine visits to active volcanoes

like White Island, comes the risk

of tour operators and tourists being lulled

into a false sense of security.

So some of these tourists are, you know, adventure tourists.

They are going for the thrill,

just as people might go climbing

or doing some other very dangerous sport.

It doesn’t necessarily appeal to all of us,

but I guess in my mind it’s okay

if people are absolutely informed

about what the risks are.

And I think that’s the question.

Did those people understand the risk

that they may have been putting themselves at

by going to those places?

For the White Island tours,

people were given protective equipment

like gas masks and helmets when exploring the crater.

But these precautions proved defenseless

in the face of the volcanic disaster in 2019.

On the 9th of December, 2019,

at the start of the Christmas festive period,

a tourist tour group was engulfed

in a volcanic disaster.

White Island erupted in two explosions

following on in quick succession.

The series of violent blasts

flung ash over 3600 meters into the sky,

showering the volcano’s floor with hot debris.

If you’re caught underneath a very big eruption,

the sky can go black.

If you’ve got a big cloud of ash above

and ash starts raining down,

you’re in darkness.

And your car headlights,

if you’re trying to flee, don’t penetrate through the murk

because you’ve got ash falling

and you’re ingesting ash into the engines

and trying to flee.

If you’re in that situation, it’s too late.

Probably the best thing you can do

is get undercover and stay there

and hope the roof over your head doesn’t collapse.

It’s horrible to be caught

in a really big volcanic eruption.

In Whakatane town, 50 kilometers across the ocean,

smoke could be seen rising from White Island.

Forty-seven people had been on the island

when the blast went off.

We know that reunification

won’t ease that sense of loss or grief,

because I don’t think anything can.

But we felt an enormous duty of care

as New Zealanders

to make sure that we brought their family members back.

Of the 47,

20 people were killed

and 27 were injured with serious burns.

Casualties came from all over the world,

including the U.K., U.S., China, Malaysia,

Australia and New Zealand.

Rescue operations proved extremely difficult

in such volatile volcanic conditions.

The New Zealand Police dive team,

supported by the Defense Force personnel,

deployed today. Um...

They haven’t found anybody as yet.

Although in the immediate aftermath of the disaster

some survivors were rescued by boat and helicopter,

hazardous situations meant that further rescue operations

had to be put on hold.

Of course I’m worried.

I would be inhuman if I did not worry.

I have to emphasize that the risk has not gone.

The risk remains present.

But reconnaissance flights that did get close to the volcano

initially detected no signs of life there.

Prior to the eruption,

the volcano had been well monitored.

Scientists had been keeping a steady watch

to try and spot any signs or indications

of an impending explosion, but nothing major was detected.

This is attributed

to the complex submarine structure type of the volcano.

According to experts,

the volcano is highly ebullient,

engaging in a variety of eruption styles.

This makes it a complex brew

that is difficult to predict.

These eruptions are driven by superheated steam and ash

rather than lava being shot out of the magma chamber,

which can make them difficult to predict.

White Island is a submarine volcano

with only this summit crater exposed to the surface.

So if we had an eruption which was driven by magma,

so a magmatic eruption,

there are a number of things we can look for

which can tell us a little bit

about the state of that volcanic system.

So if we can think about measuring the gases

that are coming out the top of the volcano,

is there an increase of these before an eruption

or is there a decrease?

We can think about looking at the seismic signals

that volcano is producing through time.

We can also think about how that volcano is deforming,

so inflating or deflating or tilting, if you like.

At White Island, the difficulty comes

because none of these precursory events may happen

leading up to an eruption,

so it becomes very difficult to understand

what may happen through time.

Phreatic steam type eruptions

can happen so fast that there is no time to react to events.

The deadly combination of falling rocks,

wet debris jets and scorching air

can also cause life-threatening harm.

Questions are still being asked

about the White Island disaster

and why tourists were allowed to approach

New Zealand’s most active volcano.

With these volcanoes that tend to be quite persistently active

and sometimes heavily visited by tourists,

the problem, of course,

is when those volcanoes do something

that they don’t normally do

or they do something just every once in a while,

maybe every few months or maybe every few years.

It would be interesting to know, for example,

if the tourists on White Island were aware

that some of the places that they might visit on their tour

are places that volcanologists

who work for the institutions

responsible for monitoring the same volcano

would not go to because it would be deemed

too high risk for them.

One defense has been the idea

of freedom of choice and freedom of access.

Geological hazard monitors GeoNet

relayed data and information around volcanic activity

to tour operators and the police,

but some say that the decision to visit or not

ultimately lies with tourists.

The interaction between volcanoes

and the tourism industry is a difficult and fraught one.

The dangers of having people in such close proximity

to active volcanic sites, as evidenced by White Island,

cannot be underestimated.

But it can be difficult to navigate this relationship

in lower-income countries who are increasingly dependent

on the economic boost of a tourism industry

around their volcanic sites.

Mount Nyiragongo in the Democratic Republic of Congo

is one such example.

The mount, respectfully known by the local community

as General Nyiragongo,

is an active 3470-meter peak north of the town of Goma,

near Congo’s border with Rwanda,

a region that has experienced

a series of conflicts and unrest.

Nyiragongo has the largest lava lake in the world

and is one of the most volatile volcanoes.

But in recent years,

it has become a popular tourist destination.

Volcanoes, because they are often mountainous

and are in mountainous parts of the world,

the scenery’s beautiful.

So people just go and hike and enjoy the scenery.

And if it’s a volcano that’s recently been active,

there’s usually interesting rock formations to see,

there’s a sulfurous smell, maybe hot springs

or maybe some small eruptions going on,

which usually are quite safe to watch

from a range of a few hundred meters,

so they attract people.

The trouble is that just now and then

there’s a bigger than expected eruption,

and that’s what can kill people

who have gone there to experience it

and they just get unlucky.

Virunga,

Africa’s oldest national park,

started offering tours to the volcanic region in 2014.

Since then, the volcanic tour has become

one of the park’s most popular attractions

and is set to increase exponentially

as more foreign operators add the tour to their packages.

For a region still recovering

from the effects of past conflicts,

this influx of tourism and potential investment

is a much needed and sought after economic boost.

But despite the increased prosperity

that Mount Nyiragongo may attract to the Congo,

it still remains one of the world’s most dangerous peaks.

In 1977, it experienced a sizable eruption

that killed 400 people and left 400 homes

and 10 kilometers of roads destroyed.

On the morning of January the 17th, 2002,

the great mountain would erupt once again

with devastating consequences for the local community.

That morning, rivers of liquid lava

came spewing down the sides of the volcano.

One of these rivers spilled into the town of Goma,

burning swathes of jungle and properties in its path.

Large smoke plumes created by the eruption

similarly endangered the region’s famed wildlife,

including its mountain gorillas

living in the nearby peaks of Mount Nyamuragira.

The mountain gorillas are critically endangered,

and over half of the population

reside in the Virunga Mountains.

The disaster also caused

substantial socioeconomic disruption.

Thirteen percent of Goma city was ravaged.

There are about 150,000 people

that did not leave the town of Goma.

An additional 250,000 left to Rwanda,

and 100,000 people

went a bit west in a place called Sake.

The World Health Organization

estimated that close to 15,000 homes were destroyed

and 400,000 people were displaced by the disaster.

Most of the locals who were displaced

are still unable to rebuild homes on the original sites,

as these have been buried underneath the lava field.

For a country with an already struggling economy,

the volcanic eruption was a major blow,

creating a huge depression for businesses in the region

and leading to mass unemployment at the time.

Whether a volcano is dangerous or not

depends a lot about what’s happened

at that individual volcano.

So volcanic activity and volcanoes in particular,

they have their own characteristics.

So I like to think of volcanoes as having their own personality.

Each one behaves differently through time.

So about understanding the risk that individual volcano poses

is about understanding what that volcano does through time,

which is very different at each volcano.

So whilst one volcano may be very safe to visit,

it hasn’t had an eruption in hundreds or thousands of years

or by "less safe," I mean there’s less probability

of an eruption occurring,

there might be others which have more frequent,

more risky activities which will be higher probability

of getting caught up in something dangerous.

Different volcano monitoring strategies,

which are better able to predict

these changing eruptive patterns,

will have to be put in place

in order to safeguard the local community

and the increasing visitors to the mount

from future disasters.

There’s no such thing as a typical volcanic eruption.

I’ve stood next to lava flows.

You feel the heat if you’re close,

but they will trundle by you

and you can see the rock pleating over,

and it’s beautiful, it’s fascinating.

And there’ll be a smell.

There’s usually a sulfurous smell

and you can hear little cracky, poppy noises

as the surface chills to glass

and the glass flakes plink away.

It’s great to be near an eruption like that.

But an explosive eruption that’s roaring out of a vent,

you’ve got a sound like a jet engine...

and you’ve got bangs as individual explosions occur,

which are big bubbles bursting,

but you don’t to be too close to that kind of thing,

because there could be brick-sized lumps of rock

flying through the air.

And even if you’ve got a hard hat on,

one of those hits you, you’ve got a serious head injury.

And if an ash column gets too dense to support itself

and collapses back to the ground,

it doesn’t just sit there, it rushes downhill,

and you get what’s called the pyroclastic flow.

Since the eruption,

the number of seismographs in the region has increased.

This vital technology,

which is able to signal impending eruptions,

will hopefully allow scientists in the region

to be able to warn the public in advance.

So an earthquake at its most fundamental

is caused by rocks breaking and moving past each other.

So in the example where you have a volcano,

you might have a magma chamber under the ground

that’s underneath the kind of main volcanic cone.

And if magma from the magma chamber

starts moving towards the surface,

that’s going to cause small earthquakes to occur

as it moves up through the volcano.

So you can actually track the movement of magma

through volcanoes by using earthquakes

and using kind of dense networks of seismometers

that measure the ground motion from earthquakes in a volcano

to try and forecast

when a volcanic eruption is going to occur.

Volcanoes are one of the most mercurial elements of nature.

And as we’ve seen, when we add human interactions to the mix,

the results are deadly.

Volcanic monitoring is at an advanced stage,

with seismographs and super computers in some instances

able to offer early predictions to facilitate evacuations.

However, as we’ve seen in various parts of the world,

the geological benefits and stunning sights

that volcanoes provide can make them hard for us to resist.

We do not always heed the warnings.

And human complacency in the face

of such a devastating force is deadly.

The tourism industry

and its interaction around volcanic sites

is something that will need to be re-evaluated

in the future

if we hope to prevent disasters

such as the one witnessed in New Zealand.

Yellowstone is one such site

where there has been speculation and discussions

around tourism monitoring.

Yellowstone National Park

is one of the most popular natural reserves in the world.

Four million people travel to the park every year

to view untrammeled vistas,

glimpse untamed animal life

and get close to hot, gushing geysers

and simmering thermal springs.

Yellowstone also houses

approximately 10,000 geysers, hot springs and mud spots.

It is a unique geothermal hotspot.

However, the stunning natural reserve

that attracts so many

also comes with its hazards for unwary visitors.

Apart from the obvious dangers

of its wildlife and famed grizzly bears,

its unique geothermal features also pose serious risks.

Through the years, a number of scalding accidents

have been reported, often a result of visitors

getting too close to geyser basins.

But perhaps the biggest threat of all

is one that has not yet happened

and lies beneath Yellowstone.

The National Park sits atop a supervolcano.

Supervolcanoes are described as volcanic centers

that have had eruptions

covering more than 1000 cubic kilometers.

Yellowstone has had three major eruption events

in the past 2.1 million years

that have led to the creation of large volcanic craters.

When this volcano last erupted 630,000 years ago,

it had a massive eruption that formed a giant caldera.

A caldera is a large circular or oval depression

caused by the collapse of the surface

following magma removal.

The last one, formed by Yellowstone’s eruption,

measured approximately 45 by 76 kilometers in size.

But although Yellowstone has not erupted for so many years

and may seem extinct,

evidence of an active volcanic state

can be witnessed in hydrothermal activity

in the area.

Geothermal features and hot springs

are one of the key elements of volcanic activity.

They are the products of interaction

of groundwater with magma at shallow depths.

Volcanoes are really, really deadly

if you’re close to one when it erupts.

Now, what do I mean by close?

It depends on how big the eruption is.

The worst possible case

is an eruption of something like Yellowstone.

They’re sometimes called supervolcanoes,

a large caldera where you’ve got a magma chamber

10 or more kilometers across.

If that breaks through to the surface

and all the gas escapes,

you can get a column of ash rising into the sky

and pyroclastic flow sweeping out

hundreds of kilometers in all directions

and an ash cloud which will spread around the world

and block out the sunlight.

And then you lose your wheat crop

for two or three years.

That’s mass starvation,

that’s end-of-civilization stuff potentially.

The total heat flux

from Yellowstone’s geothermal features

is estimated to be around a staggering 300 million watts.

This high geothermal activity in the area

has led to researchers investigating

when the supervolcano might erupt once again.

An eruption is not expected to happen anytime soon,

or at least not in the next thousand years.

But according to research from 2017,

the volcano’s transition to active status

might happen faster than we expect.

And given the unpredicted eruptions at Mount Sinabung,

Mount Nyiragongo

and White Island,

we may have to pay closer attention.

So, what might happen

if Yellowstone were to erupt again?

If it did erupt, it could be a devastating disaster

for the entire surrounding regions in the U.S.

An eruption could lead to a deadly pyroclastic flow

made up of molten lava

measuring more than 1000 degrees.

It could also lead to the formation

of toxic ash clouds that would expand over 800 kilometers.

This thick ash would also likely cover the ground

and measure up to 10 centimeters thick,

which could potentially destroy crop growth

in the Midwest of America.

Along with the ash,

the supervolcano could release

a range of equally toxic gases,

including sulfur dioxide,

a gas that can lead to acid rain and global cooling.

However, such an eruption,

although devastating on a large scale,

especially for the western region of the U.S.A.,

would be unlikely to wipe out human life.

Another popular volcano

which is also being very closely monitored

is the notoriously active Mount Etna in Italy.

The volcano is situated on active tectonic plates

and sits on the boundary of the African plate

subducting underneath the Eurasian plate.

This has made the volcano a hotbed for volcanic activity

over its long history.

Etna, which means "I burn" in Greek,

is the largest of the three active volcanoes in Italy.

Standing at a colossal 3320 meters above sea level

and two and half times the size of Vesuvius,

Mount Etna is the highest active volcano in Europe.

Since ancient times, Etna’s ebullient activity

has continued incessantly.

This constant volcanic activity helped attract

some of the earliest traveling geologists

and birthed some of our first insights

into the origins of volcanoes.

Careful observations by these early geologists

of ancient lava flow

helped develop our understanding

of how solidified lava and ash

added to the construction of stratovolcanoes over time.

But despite its hyperactivity,

Mount Etna, like the other volcanoes we’ve looked at,

continues to attract a large human presence.

Its fertile volcanic soil benefits

the extensive agricultural activity on its lower slopes,

from vineyards and orchards

to olive groves and citrus plantations.

Its lower slopes are also home

to several populous settlements and communities,

including the city of Catania.

Approximately 25% of Sicily’s population

lives on the slopes of Mount Etna.

Its rich history and stunning scenery

also attracts its fair share of tourists,

with thousands flocking to the volcano every year.

This human presence,

combined with Etna’s high volcanic activity,

has led to a number of deadly incidents

through the centuries.

In the 20th century, Etna’s hyperactivity continued.

The 1920s saw a series of eruptions,

including a major one in 1928.

In November of that year, an explosive eruption

led to the destruction of Mascali,

a town located on the eastern flank of the volcano.

The next explosion that would rock the volatile mount

would be in 1950.

In the festive month of December that year,

disaster struck.

A titanic wall of scorching molten lava

measuring nearly 10 meters high surged down Mount Etna.

The incendiary landslide blazed through villages

on the volcano’s lower slopes,

torching houses in its path.

Inhabitants again were able to evacuate successfully

and no loss of life was recorded,

but they were left devastated

by the loss of their homes and cherished farmlands.

The lava is reported to have burned through the villages,

turning vegetation, including chestnut groves,

apple orchards, vineyards and trees,

into flaming torches.

Eruptions continued through the following decades,

including the ’70s and ’80s.

In 1983, a breakthrough was made

in the strategies used to divert volcanic lava.

During an eruption in 1983, Italian scientists managed

to persuade the government at the time

that a direct intervention

to halt the volcanic process was needed.

Explosives and earthen barriers were used with some success

to divert the oncoming lava flow.

This feat wasn’t recognized

as a resounding breakthrough at the time,

but it would be the first successful intervention

that would pave the way for many more in future.

Eruptions continued through the following decades,

including a series of violent outbursts in the late ’90s.

Today, in the 21st century,

Mount Etna remains as active as ever,

with recent activity in 2017 and 2019.

In 2017,

after a few fairly quiet years,

the volcano experienced a phreatic eruption.

At the time, about 35 tourists

and their guides had been visiting the mountain

when the explosion happened.

The eruption shot lava and rocks

198 meters into the air

and did cause some harm, leaving 10 injured.

In 2019,

more activity was witnessed on the great mountain.

Italy’s National Institute of Geophysics and Volcanology

tweeted about a series of strombolian eruptions

that occurred on the volcano in May.

Strombolian eruptions are named

after the Stromboli volcano,

an active volcano on the Aeolian Islands.

This type of eruption can spurt jets of lava

tens or even hundreds of meters high.

But in this event,

the eruptions were minor,

with some spluttering of volcanic material

landing on the mount’s slopes.

What was significant about this event

was the fact that the eruption occurred

on the flank of the volcano and not its summit.

A flank eruption on the mountain the year before

had been the first for a decade.

Explosive flank eruptions pose a real threat,

as they lead to lava floods, landslides

and potentially deadly pyroclastic flows.

Although this recent flank-side eruption was concerning,

there was some reassurance in the fact

that Mount Etna is constantly monitored.

Etna is one of the most studied volcanoes in the world,

with a long history of observation.

I’ve been on Etna when it’s been erupting explosively,

with substantial ash column rising from the vent

and stuff falling on the ground

a few hundred yards in front of me.

To be honest, it’s exhilarating.

That’s fine when it stays at that level,

but if the eruption intensifies,

then I imagine it is terrifying,

because I would know the consequences

that could be coming my way.

I’d hate to be in that situation,

because there’s not a lot you can do if you’re too close.

There are currently three observatories

set up on its slopes

with Italy’s National Institute of Geophysics and Volcanology

constantly keeping a close watch.

There has also been significant development in technology

around volcano detection and monitoring

that has emerged around Etna.

The use of airborne volcano ash trackers, for instance,

have helped aircrafts learn to navigate around volcanoes

and avoid the disruption of grounding planes

and shutting down airports for extended periods

during volcanic activity.

New automated warning systems

also help predict imminent volcanic eruptions.

Mount Etna,

with its long history of volcanic activity,

has provided great opportunities

for volcanic studies

and the development of technology

around monitoring and managing eruptions.

But despite the observations

and introduction of volcanic monitoring devices,

Etna’s enigmatic eruptive pattern

and myriad of eruptive styles

makes it difficult to rule out the future threat

of an unpredicted eruption.

The tragic events around volcanoes in Indonesia,

Italy,

New Zealand and the Congo

prove that we cannot be complacent

in the face of potential volcanic eruption.

A dormant or even extinct volcano

can reanimate at any time.

And a tourist tour along a scenic route

could quickly turn into a deadly eruption zone.

You can have intervals of repose

lasting several hundred years

between one eruption and another.

And those are the worst volcanoes to deal with

because if a volcano has done nothing for hundreds of years,

the local people will regard it as safe.

"My grandfather lived here. He never had any problems.

Why should I move out?"

And even if there are warning signs building up,

it’s very hard to convince people.

Although technology is advanced

in volcano monitoring,

there is still a lot for us to learn

in understanding more complex volcanic patterns

so that seemingly invisible signals are not missed.

Volcanoes are terrifyingly awesome,

and we are drawn to them like moths to a flame.