NOVA

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.