All language subtitles for NOVA.S46E03.Kilauea_ Hawaii on Fire.480p.WEBRip.x264

Explosions.

Earthquakes.

You guys all right?

Would you get away from there?!

Lava in the streets.

This is insane.

In 2018, Hawai'i experiences

its most destructive
volcanic eruption

in over a quarter-century.

Whoa!

Residents flee for their lives.

We're packed, and
we're evacuating.

As the Earth erupts
beneath their homes.

There was a house there.

Yeah, it's gone,
it's under the lava.

And nature turns a
Hawaiian paradise

into a vision of Hell.

But through it all,

scientists are
on the front line.

Tracking subterranean
magma flows.

Think of it like a sword

cutting its way
through the rock.

Risking exposure to toxic gases.

You can actually see
all the sulfur

that is actually crystallizing.

And uncovering secrets held
inside the molten rock.

The chemistry
was extremely evolved.

All to answer the question
on everyone's mind:

How bad will it get?

Very quickly, it became
of a scale and magnitude

greater than what
we were able to handle.

"Kilauea: Hawai'i on Fire."

Right now, on "NOVA."

Major funding for "NOVA"
is provided by the following:

Whoa, watch out!

In 2018, the island of Hawai'i

becomes a living hell.

Locals rush for their lives

as red-hot lava bursts
from under their houses.

This is... I don't know, man!

Fountaining hundreds of feet
into the air.

We need medical assistance here!

It's an eruption on a scale
not seen for a generation.

450 earthquakes in
just the last 24 hours.

Upending the lives of thousands

and transforming
the landscape of Hawai'i.

But while residents evacuate,

scientists head into the field,

tracking the action to
discover what may be next.

How accurate
are their predictions?

We knew it was not if, but when.

Is this the start
of a new period

of dangerous volcanic activity?

This is unstoppable.

This is epic.

And what does it tell us

about the true nature of
the iconic islands of Hawai'i?

2,400 miles to the southwest
of the U.S. mainland

lies the Hawaiian archipelago,

a chain of tropical islands

covered in lush rainforest

and home to vibrant wildlife.

It's America's paradise
in the Pacific,

and a mecca for tourists.

But the 50th state is more
than just sun, sand, and surf.

On the southern part
of the southernmost island

lies Kilauea, an active volcano

within the Hawai'i
Volcanoes National Park.

Lava is visible
in a small lake at the summit

and at Pu'u 'O'o, a seeping vent

on the flank of the mountain.

Both sites are popular
with tourists

and constantly monitored

by a team
of on-site volcanologists.

But in April 2018,

the scientists of
the Hawaiian Volcano Observatory

become concerned
about rising levels of lava.

We had a situation where
the lava lake at the summit

was high, higher than
it had been for quite a while,

and in fact, it was periodically
beginning to overflow.

At the same time, the lava level
within the Pu'u 'O'o vent

was also very high.

One of the things we've learned

is that the magmatic system,

the plumbing system
is connected.

Magma is underground lava.

Both lava lakes are fed
from the same deep magma chamber

lying miles below the summit.

They act like pressure gauges.

The recent high levels
of the lakes

are an indication

that magma is building up
under the volcano.

The magmatic pressure
within the volcano was high.

This meant there could be
a change coming,

although we weren't quite sure
the nature of that change.

On April 30, that change
arrives with shocking speed.

In a matter of hours,

all the lava in the
Pu'u 'O'o vent disappears,

leaving a gaping hole.

It catches the volcanologists
off-guard.

We were a little surprised.

Past events at Pu'u 'O'o
have seen collapses,

short-term collapses,
but none as deep as this one.

Almost 60 million tons
of red-hot lava

have just gone missing.

The scientists have to find it,

and they fear the worst
when the ground begins to shake.

The seismograms
were off the charts,

and, you know, I knew
something big was happening.

Brian Shiro is a seismologist

with the
Hawaiian Volcano Observatory.

He monitors a network of
around 80 earthquake detectors

positioned around the volcano.

When Pu'u 'O'o's lava
disappears,

the network lights up.

Around the vent,
the land is being shaken

by a swarm of tiny tremors.

A swarm of earthquakes
is a grouping of earthquakes

close together
in space and time.

Given the context of Pu'u 'O'o,
there really was no question

what this was related to.

Below the surface,
pressure from the magma

has suddenly fractured
the surrounding rock,

opening cracks
that fill with magma,

generating earthquakes
and triggering more fractures.

A blade-like intrusion of magma
is tunneling east.

Think of it like a sword

that's traveling
beneath the ground

and cutting its way
through the rock as it goes.

It was moving underground
at a rate

probably about as fast
as you could walk.

The earthquakes indicate
the Pu'u 'O'o magma

is advancing
down Kilauea's east rift,

heading out
of the national park,

down towards the ocean
20 miles away.

Directly in its path
lie the homes

of thousands of people.

It was possible
that magma would move

through the rift zone system
and not erupt,

but there was also
a strong likelihood

that it would eventually
find its way to the surface.

We decided we must inform
the Civil Defense authorities.

We may not have
a lot of time for warning.

For 48 hours, the earthquakes
have moved east.

But suddenly they stop.

The magma is changing direction.

If the magma stops
moving sideways,

yet there's still
pressure pushing it,

it's going to have to go
somewhere.

The magma is creeping upwards.

Above lies Leilani Estates,

a sleepy neighborhood
about to have a rude awakening.

The local Civil Defense agency
puts everyone on alert.

This is a Civil Defense message.

An eruption is possible.

We were getting reports

that there was a lot
of earthquake activity.

Prepare in case
of the need for evacuation.

We were hoping for the best,

but we were planning
for the worst.

As the ground continues
to shake,

residents soon see their
neighborhood is in trouble.

Here is the crack,

just right after
the community center

and the playground.

I don't know
if you can see that.

There's my hand.

The cracks grow
in size and number.

This is new, coming
out of there.

And steam begins to billow
from the depths.

At that point,
we were fairly certain.

We knew that it
was not if, but when.

At 5 p.m. on May 3,

the ground opens
and the nightmare begins.

Oh, my God.

We're packed
and we're evacuating.

The eruption quickly becomes
international news.

A part of Hawai'i is
under a mandatory evacuation.

This right here
is a residential area

about 30 kilometers
from Mt. Kilauea,

and lava is being thrown up
in the middle of the road.

Authorities have ordered

more than 1,700 people
to leave immediately.

I heard this roar.

Almost like a fire-breathing
dragon sort of a noise.

It's the birth of a fissure.

One by one, fissures
are opening up.

Over the next few days,

the neighborhood
is ripped apart.

- This is freakin'...
- I don't know, man.

I've been crying all morning.

Lava is now pouring
over the land...

...generating multiple flows
that advance across roads...

Would you get away from there?!

...and into homes.

They are slow-moving,
but relentless.

What a flow doesn't
bury, it sets on fire.

Even as it blackens
and solidifies,

it's over
1,000 degrees Fahrenheit.

Burning its way
through the pavement.

Across the neighborhood,
residents are evacuating.

When you finally do
get back home,

what will you find?

Ashes.
It's ashes.

It's now over a week
since the fissures opened,

and the eruption continues.

To gauge the extent
of the lava flow,

volcanologist Sam Mitchell
from the University of Hawai'i

is going in for a closer look.

It's really quite something,
to be able to watch it,

and especially
to see it from up above.

15 fissures have now erupted,

spewing out enough lava
to cover 88 football fields.

It's clear
that all the fissures originate

from the same thin,
deep crack in the Earth.

At the moment, all the fissures

are erupting
along one single line,

but the lava flows can then
spread laterally either side,

and that's the biggest danger.

It's difficult to know
which fissures

will produce large flows

and how far those flows
will actually go.

This really
is an evolving story.

But now the flows
appear to be slowing.

After a week of activity,

many of the original fissures
around Leilani Estates

are sputtering to a halt.

Bill Hanson's Civil Defense team
notices the change.

There was spattering, yes,
there was noise, yes,

but there wasn't any flow;
the lava was very static.

After a week of chaos,

could the eruption
be winding down?

The only way to find out
is a risky scramble

to sample the lava.

Getting up-close and personal
to a lava flow

is not for the faint-hearted.

But for researchers

like University of Hawai'i
volcanologist Cheryl Gansecki,

what lava can reveal
about the status of the eruption

is worth the risk.

We would put out tubs
to try to catch some lava

falling out of the sky.

You really go as fast as you can

and hope you've grabbed
enough material,

so you don't
have to do it again.

Back at the lab, the
investigation can begin.

The University of Hawai'i
has built a database

of lavas collected
from previous eruptions

and created a high-speed method
of identification.

Crushing samples
from the new flows

into a fine powder

allows an analysis
of their ingredients.

All lava has a fingerprint.

Subtle differences
in chemical composition

allow volcanologists
to determine its origins.

The results are a surprise.

The lava erupting at Leilani
is not the same as the lava

that disappeared from Pu'u 'O'o
and headed down the mountain.

But it is just like lava
that they've seen before.

It was very similar in character

to another eruption

that had happened
in that same area in 1955.

Two fissures,

each about 300 feet long,
emitting lava,

extended from the Pohoiki Road
into field 114.

In 1955, a massive eruption
shook this part of the mountain.

It lasted three months,

with lava gushing
from 24 separate vents.

But evidently,

not all the magma
reached the surface

before the eruptive pressure
dropped.

Cheryl's discovery suggests

that the traveling
Pu'u 'O'o lava

encountered the remnants
of the 1955 eruption,

lying dormant
for more than 60 years,

the pressure from the fresh lava

forcing it to the surface.

Because this old magma
is relatively cool,

on contact with air,
it solidifies quickly.

But the fresh, hot lava
from Pu'u 'O'o

will be far more dynamic
if it reaches the surface.

This eruption isn't over...
It's only just begun.

What everybody was worried about

was when that Pu'u 'O'o lava
made it,

then the eruption scale
would change.

As the Leilani neighborhood

waits to see
what will come next,

alarms are sounding
at the top of the mountain,

where the summit is rumbling.

Since May 2,
the lava here has retreated,

following the Pu'u 'O'o lava
into the depths.

It's dropped 500 feet,
and is still sinking fast.

Without the lava
to support them,

the sides are slowly collapsing,

falling on top
of the descending lava

and generating ominous clouds
of ash and dust.

Just four miles away
lies the small town of Volcano.

Residents Tom Peek
and his wife, Catherine Robins,

are preparing
for what might be coming.

As soon as the ash
starts to fall,

we're tearing this down.
That's a good idea.

They fear not flowing lava,

but a deadly assault
from the skies.

As a former
National Park ranger,

Tom is a keen student
of Kilauea's explosive history.

From all that we understand,

everything is panning out
very similar.

There's some differences
in timeframe,

but there's a very parallel
kind of story developing

as if this will be
a 1924 eruption.

In 1924, the summit of Kilauea
exploded,

propelling searing ash
miles into the heavens

and showering eight-ton rocks

up to half a mile
from the summit.

The explosion
was probably triggered

by a build-up of gas.

When the magma level drops,

falling rubble will eventually
block the narrow feed pipe

like a cork in a bottle.

If the magma drops
below the water table,

steam will form in the gap.

The build-up of pressurized gas

can cause violent explosions,

firing red-hot rock and ash
thousands of feet into the sky.

Our geophysicists
were able to model

at that current rate of
draining of the lava lake,

when the level would pass
what we believed to be

the level of the water table
within the volcano.

So we had projected
the middle of May

as the likely window
for onset of explosions.

While residents near the summit

anxiously wait for Kilauea
to blow her top,

back down the mountain,

the Leilani neighborhood
faces a new threat.

The media broadcast
a dire warning.

Gas so toxic it's
killing trees and grass.

The fire crews
that are out there

have reported
those toxic levels;

it can be fatal.

Despite the lull
in eruptive activity,

the gas is now being detected
all around the neighborhood.

Forced to wear protective
breathing equipment,

volcanologist Sam Mitchell

has gone in to investigate.

Only a few days ago,

this was actively erupting lava.

You can really feel the heat
coming off

of some of these fissures
right here.

It's really something.

The air is filled with steam,

and invisible toxic gas
rises from the cracks.

The giveaway:

yellow mineral deposits
around the fissures...

Sulfur.

As we walk along,

you can actually see
all the sulfur

that is actually crystallizing
out of these gases

in the cracks.

See how intense the color
of these crystals are.

Like, it's precipitating out
pure sulfur here.

The particles of sulfur

indicate that the air
is filled with sulfur dioxide,

bubbling out from the magma
deep below.

In the presence
of moisture and sunlight,

the sulfur dioxide forms vog,
a volcanic smog

containing tiny droplets
of sulfuric acid.

It makes eyes burn,
lungs inflame,

and can even corrode metal.

At high levels,
it can be deadly.

Wow! This is really...

Really, really outgassing
at the moment.

High levels of sulfur dioxide

continue to pump into the air
each day,

a sign that magma is building up
just below the surface.

In another part
of the neighborhood,

the gas
has temporarily dissipated.

Stacy Welch left her house
in a hurry two days ago.

The authorities have given her
a few hours

to enter the danger area
and check on her property.

The vegetation shows the
signs of sulfur poisoning.

All my grass is dead.

It's definitely changed color

since I was here two days ago.

Definitely see a difference
in the landscape and everything.

Fortunately, her house
is still untouched by lava.

Hey, Mom, it's me.

We're okay, we're still safe.

But as she makes her inspection,

there are further indications
that the eruption is not over.

Wow, did you hear that?

I don't know where it's at.

Just... scary.

So scary.

It's time to leave.

Although the fissures here
have been quiet for days,

there are signs
that the lull is over.

I can hear these explosions

happening somewhere here
on the left.

There's something happening
just around the corner here.

You can really see the heat
that's coming off

at the end of the road here.

You can see the heat waves, wow.

I think I can see a red glow
just over there, on the side.

Something's on fire.

Yeah, the vegetation's
caught fire.

So it's likely there's
a small breakout of lava.

This just shows that
these fissures can reopen.

At this stage,

we should be hesitant
of actually getting any closer.

The activity
is really, really picking up.

Streets away, as Stacy
retreats from her property,

she encounters a new flow.

Is that lava?

We were here two hours ago

and it was not this advanced,
so it is really moving now.

I thought it was taillights
when we pulled in.

But that is definitely
not taillights.

That is 100% lava.

This flow is a sign

that the nature of the eruption
is changing.

The fountaining lava
is hotter and moving faster

than the old lava
that erupted a week ago.

This is the fresh lava
from Pu'u 'O'o

that's finally
reached the surface.

This eruption has
just become more dangerous.

At any time, my house could go.

This is... this is unstoppable.

This is... epic.

I'm never gonna
get this close again.

I don't think I ever
want to be this close again.

And this is scary
and we are not safe.

With lava on the move,
there is just one option:

get out of the way.

It's a reality
that's been faced here

since time immemorial.

Ever since the first people
arrived

on these bountiful islands,

a wealth of beliefs and legends
has sprung up

to account for these
devastating natural disasters.

In Hawaiian culture,
Pele, the goddess of fire,

resides within the volcano.

A lot of people have used
the term that she's "upset,"

so she's taking out houses,
and that's why

there's a lot of destruction
and devastation.

She's doing what she does.

We're in her space.

If she takes the house,
she takes the house.

If she decides
to move around the house

and spare the house,

she decides to move around
and spare the house.

But there's temporary permanence

to living within the boundaries
of Pele's domain.

Building a home here
has always been a gamble.

And sometimes,
your luck runs out.

May 17,
two weeks into the eruption.

Just past 4 a.m.,
cameras on the peak

of Kilauea's big sister
Mauna Kea

catch a huge ash cloud bursting
from the summit of Kilauea.

It looks like
the summit explosion

predicted by the scientists.

News media pick up the story.

Stunning images tonight:

that powerful explosion
at the summit of Kilauea

shooting a plume of ash
some 30,000 feet into the air.

It's the first sign

that bigger explosions
might be on the way.

But could it get even worse
than the 1924 event?

As magma exits
the chamber beneath,

heading down the mountain,

the crater above is collapsing
inches per day

in a series of earthquakes.

If the collapse continues,

it could lead
to an even bigger threat.

A pyroclastic surge:

a superheated ash cloud
of vaporized rock and magma

capable of flowing
across the landscape

at hundreds of miles an hour,

obliterating all it touches.

Hundreds of years ago,

a collapse of Kilauea's crater

led to a similar event.

In 1790, there were
quite large surges

of this hot gas and ash

that killed quite a few people.

One of the big concerns was,
if this thing gets too big,

are we going to go
into a pyroclastic phase?

The local residents are
increasingly concerned.

Here's another plume
coming up right now.

It's maybe 7,000 feet high,
maybe eight, I don't know.

But I certainly
did not expect to see

what I've seen pictures of
about 1924,

and I'm certainly hoping
not to experience

what I'd read about from 1790.

The collapse is a worrying sign

that events may be escalating.

Could it be linked
to violent new activity

now occurring down the mountain?

Around Leilani Estates,
the lull is over,

but the focus of eruptive
activity has moved east.

Two new fissures have opened.

One of them, fissure 17,
is pumping out exploding lava.

Shooting huge chunks,
some as heavy as a refrigerator,

hundreds of feet in the air.

These lava bombs are responsible

for the eruption's
first casualty.

The media report on a resident

struck by a bowling ball-sized
lava bomb

that nearly sheared his leg
in half.

The most forceful impact
I've ever had in my body

in my life.

So is this a sign

that a new type
of explosive magma

is building up under Kilauea?

Cheryl's lab quickly
analyzes fissure 17 lava.

They find it has
an unusual consistency.

Most Hawaiian lava
is as runny as ketchup.

It rarely holds on
to much magmatic gas.

The gas bubbles in Hawaiian
magma can rise freely,

and they just basically,
just burst at the surface

and release the gas.

But fissure 17 lava
is rich in silica,

the main ingredient
in common sand.

The silica thickens the lava

to the consistency
of peanut butter.

The stiffer your magma,
the more viscous it is.

So when gas bubbles
are trying to escape,

they can't expand very well,

and they tend to build up
a lot of pressure

and then explode.

Most volcanoes around the world

are fed by silica-rich magma,

explaining the prevalence
of explosive eruptions.

If magma this thick
were to build up

beneath Kilauea's summit,

a major explosion
could be in the cards.

But Cheryl's team
have found chemical evidence

that the fissure 17 lava is not
fresh from the summit at all.

It seems to come
from another hidden remnant

of extremely old magma
from a previous eruption,

even older
than the 1955-type magma

originally encountered
under Leilani Estates.

The chemistry
was extremely evolved,

meaning that it had been
stored longer

than anything we'd ever seen
erupt on Kilauea.

The longer a magma is stored,

chemical changes increase
the concentration of silica.

Fissure 17's lava is explosive,

but it's tied
to a small, isolated pocket

of thickened magma.

This discovery indicates
that the explosive lava

is unrelated
to the events at the summit.

And for now,
the collapse of the crater

is not great enough to trigger
a pyroclastic eruption.

But the ground
continues to shake,

and the summit
is still subsiding

as more and more magma
exits the chamber beneath,

heading for the open fissures.

Down the mountain,

the thick silica-rich lava
of fissure 17

is starting to congeal.

But as pressure
from the summit continues,

forceful new fissure
are opening behind it,

generating new flows
heading in many directions.

Understanding where
the lava was going

was absolutely critical

to providing
situational awareness

for the civil authorities

and issuing public warnings
in time.

With multiple fissures erupting,
this was a challenge.

Luckily, the authorities

can call on some
state-of-the-art technology.

We were requested
to help participate

by Hawai'i County Civil Defense.

And so we said, "Of course,
whatever we can do."

Ryan Perroy's team
from the University of Hawai'i

has been experimenting
with drones

to track lava flows.

Now their expertise
will prove vital.

By returning repeatedly

to a GPS-determined fixed point
above the lava's edge,

the drones accurately plot

precisely how fast
a flow is advancing.

And unlike helicopters,

drones can safely operate
day and night.

It's critically important

to be able to monitor the flows
on a 24-hour basis,

because even if everybody's
asleep, you know,

the lava's going
to potentially advance.

Using thermal cameras,
they can register

the heat signatures
of hidden subterranean cracks,

helping to forewarn which ones
may evolve into new fissures.

And they can help determine
which parts of a flow

may lead the next advance.

We've got areas down here
which have cooled off.

These are probably
not the places

where you're going to expect
to have new breakouts.

You're going to see them
here and here.

Drone predictions become vital

to the emergency services,

who are able to clear everyone

safely out of the paths
of the multiple advancing flows.

But though tracking
its short-term movements

can be complicated,
if it keeps flowing,

a red-hot lava river
will always head downhill.

Over three days,
the new flows make their way

down to the ocean.

But even as they arrive,
their power wanes.

The pressure of magma
coming down the mountain

is now reinvigorating
old fissures,

moving the center of activity
back to Leilani Estates.

Lava is gushing
faster than ever before,

and pooling
within the hardened banks

created by the earlier flows.

Levels are rising by the
hour, as lava pumps out

at over 40 cubic feet
per second.

Those rates
of eruptive activity,

rates of lava flux,

really had not been seen
at Kilauea before.

If it was able to sort of
overflow those banks,

then all bets are off

in terms of where
it's going to cover next.

Residents who thought
they'd escaped the worst

are about to be hit again.

It was just building up
and building up

till surface tension
gave and it spilled over.

This is insane.

Lava's moving,

encroaching at the rate
of one property a minute.

Very quickly, it became
of a scale and magnitude

greater than what
we were able to handle.

The authorities scramble
to warn nearby residents,

while drones keep an eye
on the advancing lava.

Watching live drone footage
at Civil Defense Headquarters,

Bill Hanson
suddenly spots something

in the depths of the forest.

The lights were flashing.

And I looked at it,

and I said, "Guys, do you know
what he's doing?"

He's flashing S.O.S."

Forced to abandon his car,

a resident has
become disoriented,

his cell phone his only link
to his rescuers.

A 911 operator patches him in
to the Civil Defense team,

who summon the drone to his aid.

And so we told him,
"Can you see the drone?"

He goes, "Yes,
I can see the drone."

And we said, "Please
follow the drone out..."

The drone will lead you
to safety."

Assisted by the flying beacon,

the man is able to find his way
out of the forest,

and make contact
with the rescue team.

And everybody was, of course,
elated

that we were able
to work technology

into saving a life.

That was a really special story

that we were proud
to be part of.

The eruption has now entered
a new phase.

From this point on,
one fissure starts to dominate...

Fissure eight.

Its flow rate is so great

that the spatter
forms an immense cone...

...as it pumps out

over 3,000 cubic feet of lava
per second...

...forming a vast river
hundreds of yards across.

It is an awe-inspiring thing

to watch these flows
and watch them evolve

and change over time,

and to see these immense
channels and rivers of lava

just passing underneath you.

It is a very
humbling experience.

The new flow powers forward
for miles and miles.

It's now clear
the effects of this eruption

will be widespread
and long-lasting.

Countless more acres
will be poisoned

or buried
under a red-hot blanket.

But for the Hawaiian ecosystem,
this is not the calamity

that it first appears.

The wave of destruction
may ultimately generate

the seeds of life.

Rick Hazlett,
from the University of Hawai'i,

is investigating a cave
hidden in the rainforest.

A gateway to
the Hawaiian underworld,

revealing subterranean secrets
about the island's formation.

To enter one of these caves

is like seeing
the inside of an eruption.

This is a lava tube.

Countless numbers of these
huge subterranean tubes

crisscross Hawai'i.

Some, like this one,
can be over 30 miles long.

They are the remains
of lava flows

that hardened on the outside,

but stayed liquid on the inside,

continuing to flow
for months or years

until they ran out of lava.

So like a dam
or a reservoir draining,

the lava emptied this passageway
and exposed the cave

that we can enjoy
and explore today.

You don't see lava tubes

in many places around the world.

Unusually hot lava is needed
to maintain tunnels

that can extend
such great distances.

But Hawaiian volcanoes cook up
some of the hottest lava

on Earth,

over 200 degrees hotter
than most other volcanoes.

So Hawaiian flows
can spread the lava

far and wide.

They're landscape builders.

They're like a metro system
delivering passengers

here and there.

In this case, the delivery
is molten lava,

and the product is a new
landscape, a larger island.

Lava flows aren't
a curse upon Hawai'i.

They are Hawai'i.

Essentially,
100% of the landscape

that you view in Hawai'i

is made up of lava flows
piled one on top of the other

to build these volcanoes
in the sea.

And it turns out

that this hardened lava
is rich in nutrient chemicals.

As the lava breaks down,

it produces some of the most
fertile soils on the planet.

From the ashes of destruction,
tomorrow's forests will be born.

And there's another distinctive
feature of Hawai'i's volcanoes...

Their sheer size.

Take away the ocean,
and they are revealed to be

the highest mountains on Earth.

At over 30,000 feet,
Kilauea's neighbors,

Mauna Kea and Mauna Loa,

put even Everest in the shade,

all built by a powerful
and persistent supply of magma.

Hawaiian volcanoes are maybe
the most productive volcanoes

on Earth.

They erupt very frequently,

and just keep piling on
more and more and more.

So what is so special
about Hawai'i

that it can supply
such an abundance

of extra-hot magma
to its volcanoes?

Kilauea is situated
on the southeast end

of the island chain.

As you move northwest, the
volcanoes become less active,

and the lava flows more ancient.

It's a sign that
the Hawaiian chain may be formed

by a powerful force from the
depths... a subterranean hotspot.

Hotspots are generated
by plumes of hot, softened rock,

rising up
from deep in the mantle.

When they contact
the Earth's crustal plate,

the magma infiltrates
the solid rock.

Over millions of years,

as the plate
passes over the hotspot,

a chain of islands is created.

The plume hypothesis can explain

why Hawai'i's lava is so hot
and so abundant.

And why these islands grow
at such an impressive rate.

In 2018, this growth
is on stark display.

In the first week of June,
the main flow from fissure eight

advances
through residential areas.

Hundreds more islanders
are forced to evacuate

as it makes its way
to the ocean.

This time, when it hits,

the flow shows no sign
of dying down.

Wherever the front of
the flow meets the ocean,

there is an explosive reaction.

Sending lava bombs
hundreds of feet into the air.

On July 16,
a boatload of tourists

get more than they bargained for

when they get too close
to an explosive front line.

They are lucky to survive
relatively unscathed...

A few nasty burns
and one broken leg.

From the violent clash
between ocean and lava,

new land is born.

Coastal waters
have been pushed away,

replaced by a lava delta
with an area equivalent

to nearly 700 football fields.

As long as the volcanoes
stay active,

this island will continue
to grow.

But while volcanic eruptions
are busy building up Hawai'i,

other processes are busy
bringing her down.

Her first enemy
is the tropical climate.

Hawai'i is the wettest
state in the U.S.A.,

drenched by an average

of over five feet of rain
each year.

This deluge results from the
combination of high mountains

and an enormous ocean.

Moist air coming off the sea
hits the land, rising, cooling,

and releasing downpours

that begin a process
of quiet destruction.

Volcanic basalt is a porous rock

highly susceptible
to the elements.

Rock such as this,
the basalt that erupts

and builds these volcanoes
in Hawai'i,

is especially prone
to weathering

in Earth's atmosphere.

Compared to other rock types,
like granite,

rocks like this,
exposed to moisture

for very long periods of time
in this warm climate,

will slowly dissolve.

You have to think
of the Hawaiian Islands

as being temporary
geographical features.

The islands are fragile.

Weathering, erosion,
and massive landslides

mean they are continuously
crumbling away.

But more importantly,

as the islands drift away
from the hotspot,

the cooling plate descends,

drawing them slowly
beneath the ocean.

It's been happening
for millions of years.

To the northwest
lies the Emperor Seamount chain,

stretching thousands of miles...

Relics of previous generations
of Hawaiian islands,

now submerged shadows
of their former glory.

In 2018, another island remnant
disappeared beneath the waves,

the last sands of East Island
swallowed by the sea.

So is the Hawaiian archipelago
doomed to disappear?

There's new activity just to the
southeast of the Big Island.

It's attracted SS Nautilus,
a research vessel.

From here, oceanographers
are guiding a submersible

down into the depths.

We're working down
about a mile underwater.

It's very dark there...
It's perpetually dark there.

The submersible
has reached its target.

It's time to light up the scene.

The steepness of it
is so remarkable...

Look how that drops away
down the other side.

It's incredible.

It's brutal.

The team find
what they are looking for...

A hydrothermal vent.

What's very exciting

is that right now, it is active,

and there is hot water that's
venting from certain regions.

The water around the vent
is close to boiling point.

It's hot
because this piece of land

is the summit of Lo'ihi,

an active volcano
submerged beneath the ocean,

created by the same
geological hotspot

driving the eruptions
on the island above.

Lo'ihi is over two miles high,
and growing inches per year.

This is something which will
progress on its own time.

We're going to have to wait
hundreds of thousands of years,

would be my guess, or at least
tens of thousands of years,

before we see anything
that'll breach the surface.

Lo'ihi will likely
form the next island

in the Hawaiian archipelago...

...proof that as old islands
sink beneath the sea,

new islands will rise
to replace them.

Hawai'i will survive.

It's weeks later, early October,
and Leilani Estates is quiet.

The 100-foot cone
of fissure eight,

the center of so much
activity, lies dormant.

For over a month,
the scientists have detected

little eruptive activity
anywhere on the volcano.

There is no molten lava

in this area at the surface.

There is no molten lava
anywhere on Kilauea volcano.

For the Leilani eruption,
it's over.

This eruption lasted
over three months,

producing enough lava
to bury the whole of Manhattan

nearly 30 feet deep.

It covered
nearly 14 square miles,

and built 875 acres of new land
in the ocean.

At the top of the mountain,

the dreaded summit eruption
never materialized.

But the draining
of the magma chamber

led to an epic
slow-motion collapse.

The crater is now
15 times larger,

and deeper than the
Empire State Building is high.

Those who chose to live
on the slopes of Kilauea

are counting the cost

of their high-stakes bargain
with paradise.

Over 700 properties
were swallowed by the lava.

Stacy Welch is
one of the lucky ones.

Her house is still standing.

I'm still in shock.

It's just the power of nature...
It's unbelievable.

That's incredible to me,

to have something just come
and wipe everything out

when there were 700 homes there,
and now there's nothing.

There are no words sometimes.

The healing from this is,
it's going to be lifelong.

It makes all your other problems
look really small

when you're dealing with lava.

I would not have wanted
to miss it,

but I don't want it
to happen again.

You know, we all know
that there's a possibility

that we may not have a house
tomorrow.

But if we can live with her,
if we do what we need to do

in taking care of our land,

that's the ideal of what I think
is being Hawaiian.

In 2018, Kilauea proved
her destructive potential.

But if science tells us
anything, she isn't done yet.

Scientists are confident
that someday,

in the not-too-distant future,

the lava will return.

Even though there may not be
lava moving across the surface,

HVO is still on guard
and being vigilant

and watching the activity,

looking for changes
that might mean

that more dangerous activity
is coming.

This is a very active volcano,

and it will erupt again.

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