Original subtitles

>> Earth, a 4.5 billion year old

Planet, still evolving.

As continents shift and clash,

volcanoes erupt, glaciers grow

and recede, the Earth's crust is

carved in countless, fascinating

ways, leaving a trail of

geological mysteries behind.

This is the story of Hawaii, a

mountain chain over 80 million

years old and home to the

most active volcano in the

world.

In this exquisite, volatile

landscape, scientists hunt for

clues to the islands'

origins - clues that may shed

new light on the formation of

the Earth itself. S01x12 Hawaii Original Air Date on May 5, 2009

-- Sync, corrected by elderman -- -- for MY-SUBS.com --

Hawaii. The most isolated group

of islands on Earth, stretching

1,500 miles across the middle of

the Pacific Ocean.

These eight tropical islands are

one of the youngest geological

formations on the planet.

With stunning beaches, huge

canyons and the biggest

volcanoes on Earth, this is

where paradise meets hell.

The investigation into how

Hawaii was formed began in 1934.

Dutch geophysicist Felix Meinesz

invented the gravimeter, an

incredible machine which enabled

scientists to accurately measure

gravity for the first time.

With his cutting-edge

technology, Meinesz was able to

calculate the gravitational

forces at work on the Big Island

and, using this data, determine

its size.

His results revealed that the

Big Island was like a gigantic

iceberg. Only its tip was

visible above the ocean. But

drain away the water and its

true size is remarkable. The

island is twice the height of

Everest, and so massive that

Everest could fit inside it 140

times.

Geologist Mike Poland heads to

the top of the mountain Mauna

Kea, the highest point on the

Big Island, to get a sense of

its true enormity.

>> We're standing at the top of

Mauna Kea volcano, which is the

tallest mountain in the world.

It's 13,796 feet above sea

level, but it goes all the way

down to the ocean floor and

ends up being about 56,000 feet

high.

>> This giant island is the

largest in the United States and

bigger than all the other

Hawaiian Islands put together.

Intrigued, scientists set out to

discover what could have created

such a huge land mass.

10,000 feet below the peak of

Mauna Kea and 70 miles to the

south, the prime suspect is

plain to see - the awesome

Kilauea volcano.

>> (Poland) We like to call

Kilauea the most active volcano

in the world because it's been

erupting continuously since

1983. And it's been going every

day, almost nonstop, since that

time. Since early 2008, it's

been even more active, 'cause

now we have this summit

eruption as well, so now

Kilauea's perhaps by two times

the most active volcano in the

world.

>> But this volcano is not

predictable. Although the summit

is no longer spewing out lava,

12 miles down on the south flank

of the volcano is an active

vent.

For the last 25 years, lava has

been gushing out of the side of

the volcano from this vent,

with no signs of stopping.

Homes, towns and forests are

swallowed up by scorching hot

lava. With each new flow, layer

upon layer of black crust

builds, covering the island in

volcanic rock.

Could this huge island have been

built entirely by lava?

Experts needed to figure out

exactly how much lava Kilauea

produces. Their first clue can

be found all over the volcano.

Clinging to the rocks are yellow

crystals. These are sulfur

crystals and tell scntists

that Kilauea volcano is

releasing vast amounts of

sulfur dioxide gas.

To determine just how much the

volcano is producing,

researchers take regular

measurements.

>> The amount of sulfur dioxide

that effervesces from the magma

is tied directly to the amount

of magma that's coming out of

the ground, the amount of lava

that's erupted. So by measuring

the amount of sulfur dioxide,

we can use that number to

calculate how much lava is being

erupted.

>> These samples reveal

staggering results.

Kilauea could be producing 100

million cubic yards of lava a

year, more than any volcano on

Earth. But there isn't this much

lava flowing across the surface.

So where does the rest of it go?

Geologists ventured below the

surface, into the guts of the

volcano, to investigate.

Stretching 400 feet into the

dark is a strange tunnel, just

like a subway tunnel. But it's

not a manmade structure. It's

part of a vast network of tubes

that hold the key to how much

lava moves around the island.

>> We're standing in Thurston

lava tube in Hawaii Volcanoes

National Park, and this lava

tube was one of the main

conduits for lava that was

flowing from Kilauea summit

to the sea in an eruption that

occurred about 500 years ago.

So once this tube system has

been established, you

essentially have an underground

river of lava. So these tube

systems can be very long-lived

and very efficient delivery

systems for lava.

>> The lava is so hot it burns a

channel into the rocks beneath

it.

This incredible time-lapse

footage shows that, because the

top of the flow is still exposed

to the air, it cools and crusts

over. Below this crust, a tunnel

forms, through which the lava

continues to flow.

But how much lava can these

tubes carry?

Back on the surface, Dr. Ken Hon

is carefully inspecting the lava

fields to find an active tube.

Only inches beneath his feet

could be a tunnel full of 2,000

degree lava.

Dr. Hon is on the look out for a

skylight, a window in the

ceiling of a tube. They can come

and go within days and are a

sure sign of an active lava

tube.

>> You can see the lava glowing

inside the lava tube. This one's

about ten to 15 feet wide and

probably about five feet deep.

And it's about 2,000 degrees

Fahrenheit, and it glows like

the sun.

>> These hidden tunnels keep the

lava insulated and hot,

preventing it from cooling and

turning into solid rock,

enabling it to travel further

and faster than lava on the

surface.

>> What we're looking at is on

the order of about five cubic

yards every second going

in this lava tube underneath us.

And that's the equivalent of

about a dump truck worth of lava

every two seconds, so if I was

standing on the freeway, what

you would see is one dump truck

after another dump truck after

another dump truck going by me

here, transporting a phenomenal

amount of material.

>> Hundreds of these expressways

crisscross the island, carrying

lava underground up to 30 miles

until it reaches its inevitable

destination...

the ocean.

And when 2,000 degree lava meets

seawater, the results are

spectacular.

This interaction is key to how

the Big Island was created and

is continually growing.

>> When the lava hits the ocean,

it's extremely hot and it

shatters into lots of little

pieces, so what it does is leave

a lot of black sand behind it.

>> Layer upon layer of this

black sandy rubble slowly piles

up on the ocean floor until it

forms a new beach.

New lava on the surface runs

across this beach, cooling

slowly to form a new piece

of solid land on sandy

foundations. This massive island

is built on piles of loose

rubble.

>> We're looking right here at

the process by which the

Hawaiian Islands grow.

>> The Big Island is the fastest

growing piece of land on Earth,

as lava from Kilauea adds 20

football fields a year to its

already colossal size. But this

just isn't enough. More lava is

needed to build this huge

Island, so just where is it

coming from? The clues are in

the landscape itself. While

Kilauea forms only one peak on

the island, four other

megastructures tower over the

landscape.

>> Over a million years ago,

there was no Big Island of

Hawaii. It started as a very

small island, which was the

volcano of Kohala, which grew

out of the ocean. Over time,

more volcanoes started to grow,

Mauna Kea and Hualalai came

next, growing into tremendous

Mountains. Mauna Loa was the

next volcano to grow. And

Kilauea is the youngest of the

Big Island's volcanoes.

>> Over a million years, lava

from these five volcanoes slowly

built the Big Island up from the

sea floor. The biggest island in

the United States is one big

volcanic rock.

The mystery of how Hawaii was

made is slowly unraveling as the

evidence emerges from its fiery

volcanoes. Experiments in the

1930s revealed that the Big

Island is a vast structure,

stretching three miles down to

the sea floor. Readings of

sulfur dioxide gas show that

Kilauea produces more lava than

any other volcano on Earth.

The landscape reveals that lava

from five volcanoes built the

Island.

The Big Island of Hawaii is a

stunning wilderness dominated by

fire and destruction. But what

force on Earth could create the

most active volcano in the

world, 2,000 miles from the

nearest land, in the middle of

the Pacific?

Hawaii is filled with evidence

of a volcanic past.

The eight islands are made up

of 15 mammoth volcanoes.

Molokai boasts two huge

mountains, the Big Island is

dominated by the giant Mauna

Loa, and in Honolulu, houses are

crowded around the now extinct

Diamond Head crater.

Geologists had figured out that

the Big Island was created by

five volcanoes. Next, they

wanted to know how the entire

chain had come into existence.

7,000 miles away, off the coast

of Indonesia, is the mighty

Krakatoa.

Ever since it exploded in 1883,

scientists have been trying to

understand the forces that

create volcanoes.

Experts plotted all the active

volcanoes in the world on a map,

and an extraordinary fact

emerged. 80 percent lay around

the edge of the Pacific Ocean.

This long line of volcanoes

became known as the Ring of

Fire. 452 giant volcanoes make

up the ring, and it is thought

that eruptions began in this

area over 36 million years ago.

During the 1950s and '60s, a

theory emerged that finally

began to make sense of these

fire mountains. Geologists

realized that the Earth's crust

was made up of eight major and

many minor plates, fitting

together like a giant jigsaw

puzzle.

>> They move relative to one

another, sometimes they

intersect, sometimes they

diverge. These plate boundaries

are where we see most geologic

activity. For example, along the

Pacific Ring of Fire, where

there's lots of volcanoes and

earthquakes, that marks plate

boundary locations.

>> The theory was called

subduction. When tectonic plates

collide, the heavier oceanic

plate is forced down into the

Earth's intensely hot interior,

taking water with it. The water

forces magma to swirl up and

push through the plate, where it

forms volcanoes.

But when geologists looked at

the volcanoes of Hawaii, it was

clear the theory didn't fit.

They couldn't have been created

as the plates collided, because

they sit 2,000 miles from the

nearest boundary.

>> Here in Hawaii, we're in the

middle of a plate, so we

wouldn't expect to see that much

activity. That's another bit of

evidence that there's got to be

some anomaly here that's

causing all of the melting we

see in the middle of this large

plate.

>> Puzzled, geologists decided

to look at the volcanoes of

Hawaii in the hope they might

give up their secrets. But all

they found were more

differences. Most of the world's

volcanoes are cone-shaped, with

steep sides many thousands of

feet tall, but Hawaii's

volcanoes look completely

different.

>> We call these volcanoes

shield volcanoes because of

their shape. If you're looking

behind me at Mauna Loa, it's

got these very smooth sloping

flanks, it's like a warrior's

shield that's been put on its

end.

>> Digging deeper, geologists

decided to test the lava and

found that Hawaiian volcanoes

produce a distinct type of

lava called basalt. Basalt lava

is made of rocks which have been

heated up to 2,000 degrees.

Not only is it the hottest lava

in the world, it's also some of

the most fluid, and this makes

it terrifyingly unpredictable.

>> (man) We gotta get outta here!

Get outta here!

>> The lava that erupts here in

Hawaii is very runny, it's much

runnier than the kind of lavas

that erupt from places like

Mount Rainier or Mount St.

Helens, which is much stickier.

It's like comparing honey to

toothpaste.

>> It's this difference in the

consistency of the lava that

gives Hawaii's volcanoes their

dramatically different shape.

>> The sides of the volcanoes

here are gently sloping because

those lava flows can just run

out as they need to.

And the lava flows at places

like Mount Rainier and Mount St.

Helens, being very sticky, stay

close to the volcano and build

up very steep-sided volcanic

cones.

>> Geologists had uncovered

crucial evidence, but they still

did not understand what kind of

force could create volcanoes in

the middle of a plate 2,000

miles from the nearest boundary.

But whatever that force turned

out to be, it would have to be

enormous. Big enough to quite

literally move a mountain. At

the summit of the Big Island's

Kilauea volcano, Dr. Mike Poland

is using sophiicated global

positioning equipment to measure

changes in the volcano's size.

>> G.P.S. is a tool for locating

yourself anywhere on the surface

of the Earth. You may be

familiar with this from seeing

G.P.S. units in cars. This is a

different type of G.P.S., it's

much more accurate. And that

allows us to see how the ground

is moving in centimeter-level

scales.

>> This cutting-edge technology

is crucial to scientists in

their struggle to understand the

forces working beneath Hawaii.

>> So we've got this G.P.S.

setup here, we also have a

G.P.S. setup on the far side of

the aldera. Now, by looking at

how the distance between those

G.P.S. stations is changing, we

can get an idea of whether or

not the volcano is inflating or

deflating. If it's inflating

like a balloon, it means that

there's magma that's

accumulating beneath the

surface, and if it's deflating,

it may mean that there's magma

that's leaving the subsurface.

And over the past years,

actually, these stations have

gotten farther apart from one

another by almost a foot. The

kind of force necessary to

inflate the volcano, to spread

the Caldera wider by one foot,

is tremendous, and it's a very

good sign of magmahat's

accumulating beneath the surface

and may be getting ready to

erupt.

>> Evidence was mounting that a

huge and unexplained force was

at work beneath the chain. The

volcanoes of Hawaii do not

emerge from a plate boundary,

but rise up right in the middle

of the Pacific plate. Hawaii's

Lava is dramatically different

to that produced by the rest of

the volcanoes in the Pacific.

The islands of Hawaii were a

thorn in the side of geology.

But, although they remained an

unexplained mystery, geologists

weren't about to give up. And

the answers they would find were

so incredible that the debate

they created still rages to this

day.

The puzzle of what created the

Islands of Hawaii seemed

impossible to solve.

The mystery only deepened when,

in the 1950s, the U.S. Navy

mapped the ocean floor with

sonar.

They revealed a series of

underwater mountains, known as

Seamounts, that extended far

beyond the chain of eight

Hawaiian Islands.

>> To the northwest are a whole

string of sea mountains we call

Seamounts. Those are sunken

volcanic mountains, many of them

with reefs on top of them.

>> Over 80 seamounts and 19

islands form this sequence,

known as the Hawaiian-Emperor

Seamount chain.

>> (Blay) You're looking at a

total distance from the Big

Island of Hawaii out to Midway

and all the way up to Russia of

about 3,200 miles, it's one of

the longest mountain chains in

the world, but very little of it

is above sea level.

>> In 1963, Canadian geologist

J. Tuzo wilson turned his

attentions to the Hawaiian

Islands.

He was struck by the fact that

both the Hawaiian Islands and

Seamounts form a straight line

that courses through the middle

of the Pacific.

Straight lines are incredibly

rare in nature, they don't occur

by accident, especially not a

line over 3,000 miles long.

Wilson believed that one single

force must have created this

vast chain of volcanic

Islands and Seamounts.

Wilson also made a very simple

and yet incredibly astute

deduction. The further the

Islands of Hawaii were from the

Big Island, the greener they

got. And for Wilson, greener

meant older. He noticed that the

landscape on the Big Island is

like a black desert, a barren

wilderness with only a few

seedlings peeping through the

lava. Fresh lava flows regularly

scorch the Earth, killing any

plant life.

But move north along the chain,

and the islands become

increasingly green. Wilson

believed that on each successive

Island, more time has passed

since the last eruption,

allowing more plants to grow.

Two years later, using

radiometric techniques,

scientists dated rock samples

from each of the islands.

Their results confirmed Wilson's

hunch and proved that the

Islands increased in age.

Dr. Poland has been collecting

some of these rock samples and

has brought them to the Big

Island.

>> This rock right here is from

the lava flow that we're

standing on, this is one of the

youngest rocks on the island.

And, in fact, we could go and

pick up some lava that formed

yesterday if it weren't too hot.

If we move down to the middle of

the chain, we get this rock here

which is from Oahu, and this is

about three and a half million

years old.

This rock here is from a lava

flow on the island of Kauai,

It's from the island that's the

farthest away from where we are

today on the Big Island. You

notice how dull it is, that's

because it is very old, it's

about five million years old.

>> Wilson pulled together

evidence from rock dating and

the straight line forged by the

Islands and came up with a

single theory. He proposed that

Hawaii was created by something

called a hotspot, an

exceptionally hot region beneath

the Earth's crust that was

concentrated under Hawaii's

Big Island. As the pacific plate

moved slowly over this hotspot,

the immense heat punched

through the crust to form a

chain of volcanic islands.

>> So this hot spot is a--a

constant and stationary source

of heat beneath the Earth's

surface, it's like a blowtorch

pointed up at the surface of the

Earth. And as the Earth's

surface moves over that

blowtorch, it punches through,

creating a chain of islands and

undersea mountains, and that's

what we're seeing in Hawaii

today.

>> This theory was a geological

masterstroke. It didn't just

explain how Hawaii was created,

it also confirmed one of the

most radical theories of the

20th century, the theory of

plate tectonics.

Here, at last, was evidence that

the vast lumbering plates that

made up the Earth were moving.

Tuzo Wilson's hotspot theory

changed our understanding of our

planet forever, but it also left

behind a controversy that still

rages to this day.

How was the hotspot created?

>> (Poland) Ever since scientists

understood that volcanism in

Hawaii was driven by this

hotspot, the question then

became, well what drives the

hotspot? What causes the

hotspot?

>> On the barren slopes of Mauna

Kea on the Big Island, Mike

Poland has found a clue.

>> So what we're looking at here

is what we call a xenolith, it's

basically a foreign piece of

rock that's trapped in this lava

flow.

>> It's where this foreign piece

of rock has come from that's

truly startling.

>> The green mineral you're

seeing in this xenolith here is

a mineral called olivine, and it

really indicates that--that this

chunk here came from someplace

very deep within the Earth.

>> Olivine is usually found

hundreds of miles beneath the

surface. Its presence here is

good evidence that the hotspot

is powered by something deep

within the Earth. And in the

1970s, american geologists

finally came up with a

groundbreaking theory. They

theorized that below the hotspot

lies a plume of hot rock, which

rises up through the Earth's

interior. Two or 300 miles below

the surface, it starts to spread

out, forming a huge dome. The

very top of this is the hotspot.

Scientists called this

phenomenon a mantle plume.

No one really knows how deep it

goes, but some scientists have

come to the extraordinary

conclusion that it may stretch

all the way down to the very

core of our planet.

>> It is possible that the plume

extends all the way down to the

core-mantle boundary, and

frankly, that makes good sense

to me, if you look at the size

of the Hawaiian Island chain.

It's a huge feature, it's been

around for tens of millions of

years. To me, that's not

something that can be explained

by something that's--that's just

near the surface, I think it's

got to be something quite deep

within the Earth.

>> Suddenly, experts realized

plumes were the answer to

hundreds of geological

mysteries, which had long

puzzled science, such as the

existence of Icelandic

volcanoes, the Galapagos

Islands, and the vast

Yellowstone supervolcano.

An investigation, begun in

Hawaii, transformed scientists'

understanding, not just of the

Island chain but of the entire

Planet.

Rock dating and the unusually

straight alignment of the island

chain revealed that the Pacific

Plate is moving over a

stationary hotspot. Olivine rock

erupted on Hawaii's Big Island

shows this hotspot is powered

by a mantle plume originating

from the very bowels of the

Earth. But while the Hawaiian

Islands have been created by

this very hotspot, another,

equally powerful, force is

working to destroy them.

In Hawaii, a strange force is at

work. While the Big Island is

growing by 11,000 square feet

a year, the islands at the

northern end of the chain are

vanishing into the Pacific at a

rate of 2,400 square feet a

year. These islands are

disappearing fast.

Geologists were curious about

what force could cause them to

vanish.

They found their first clue in

early scientific studies. 1950s

underwater sea mapping produced

a wealth of data, and these

results revealed something

completely unexpected.

Heat and pressure from the

hotspot had forced up the

ocean floor, creating a bulge

750 miles long and 500 feet

high. The chain is raised by the

swell, but as the islands move

away from the hotspot, they

slide off the swollen crust,

sinking further and further.

>> Eventually, as they move

northward at about eight to ten

centimeters, that's about three

and a half inches, per year--

so in, say, another, um, one to

two million years, this island

will probably be as much as

three to 4,000 feet lower,

probably have relatively little

freshwater on it and not be

very inhabitable.

>> The hotspot that created the

islands also seals their fate.

But the islands aren't just

sinking, they're shrinking too.

Erosion is the culprit. It's

slowly destroying the islands,

and nowhere is this more

apparent than on Kauai, the

oldest island of Hawaii.

Here, along the coastline,

intense weathering may have

produced some of the most

breathtaking natural features in

the world, but it is also

evidence of the island's

inherent flaw. And erosion isn't

just taking place at the coast.

It's happening all over the

island.

[birds crying]

Waimea Canyon, Hawaii's grand

canyon, a ten-mile scar through

Kauai's green wilderness.

Over 3,000 feet deep, this

canyon is the most dramatic

example of erosion in Hawaii.

>> If you look up to the east,

you'll see one of the rainiest

places in the world, Mount

Waialeale. Rain flows from that

Mountain down into the canyon.

>> Mount Waialeale receives

over 400 inches of rain every

year, which pours out over the

island, carving out the canyon.

But the islands are made of

basalt lava, one of the hardest

rocks on Earth. How could water

alone be wearing them away?

The answer lies in the canyon's

spectacular red walls.

>> The reddish color is from

the oxidation of the mineral

iron, which makes up about

ten to 12 percent of the lava

rock here. It's very similar to

the rust that forms on your car.

So, literally, we're looking at

a highly rusted landscape, if

you will, which makes it very

soft. So, in a sense, it's, uh,

somewhat rotten.

>> Exposed to water, the high

level of iron in this lava

causes the rock to rust and

crumble. It's the paradox of the

Hawaiian Islands. They're made

of volcanic basalt, one of

nature's hardest rocks, but it's

fatally flawed.

>> This, uh, rock, which, uh,

initially was, uh, very dense,

hard lava you could barely break

with a hammer, we can now

actually pull out pieces with

our hand.

>> Combine this crumbling rock

with some of the highest

rainfall in the world, and the

result is massive erosion over

millions of years. But

scientists knew that erosion

alone couldn't be causing the

islands to disappear.

On the island of Molokai, they

found evidence that vast tracts

of land had disappeared, not

over millions of years, but

overnight.

Satellite images revealed that

Molokai is not like the other

round lands of Hawaii.

>> Something strange happened to

Molokai, it's quite obvious just

by looking at any map.

It's not a round volcano, part

of it is missing.

>> It's a thin strip of land

with sharp cliff edges, shorn

away into steep faces.

At 1,700 feet, these are the

highest sea cliffs in the world.

All the evidence pointed to a

sudden cataclysmic event.

Many theories were put forward,

but it wasn't until the 1980s

that geologists got the

evidence they desperately

needed. After the success of

earlier underwater mapping, the

U.S. Navy returned to Hawaii

with the world's most advanced

sonar system and surveyed the

surrounding waters in incredible

detail. They discovered the

seabed on the island's north

side was littered with gigantic

underwater blocks of land, some

larger than the island of

Manhattan. Geologists took

thousands of samples and

measured the blocks. What they

found was incredible.

These blocks could be fitted

back to the island's steep

cliffs like a giant jigsaw

puzzle. Finally, scientists had

enough evidence to put together

a picture of what had happened.

Radiometric dating confirmed the

age of the blocks and showed

that they were the result of an

event which had taken place over

a million years ago. Geologists

knew there could only be one

explanation - a massive

landslide.

>> One and a half million years

ago, um, there was a very bad

day in the Hawaiian Islands,

the entire north slope of the

island slipped off into the

Ocean, a section 25 miles long

and perhaps as much as a mile

thick, and it did it all at

once.

>> This huge section of the

island crashed into the ocean,

splitting into massive blocks

weighing millions of tons.

The force with which they

crashed into the waves meant

they didn't stop dead but

continued to move along the

ocean floor at an incredible

speed.

>> It was sudden, it was

dramatic, and we know that

because of how far the blocks

went, they--they went down into

this trough around the Hawaiian

Islands and then up the other

side and eventually stopped

about 200 miles away. And for

them to go that far means they

had to be traveling about 150,

160 miles an hour, really fast,

and of course, it's displacing

water while it's doing that, so

you're creating for the Hawaiian

Islands a huge tsunami, a

tsunami that would have--would

have reached to the top of the

cliffs behind me.

>> A landslide on this scale and

at this speed would have

produced one of the most awesome

and deadly waves ever seen on

the planet.

>> The main event was over in

only five minutes, and, uh, and

I'm afraid that, if you saw

that, it would be too late,

because, yeah, you could run as

hard as you like and--and you

wouldn't get away from the

subsequent--the subsequent

tsunami.

>> But what could have caused

such catastrophic land failure?

Geologists look to the youngest

island, the Big Island, for

answers.

Here the island is still

building, just as Molokai once

did, and experts suspect they

will find their answer in the

island's foundations.

>> As the new land builds out,

it's building on sand that's

deposited in front of the lava

flows and so it's very unstable.

And every once in a while, this

material collapses, leaves the

lava unsupported, and it breaks

and it slides down into the

ocean.

>> It was a disturbing

discovery. All Hawaii's islands

were built rapidly and entirely

from lava. They are all based on

the same weak foundations.

And that means a landslide could

strike anywhere.

On the south coast of the Big

Island, there's evidence that

another major landslide could

be about to occur. A huge tear

in the Earth points to where a

4,700 square mile chunk of land

is breaking away from the Big

Island at a rate of four inches

a year. For its size, this is

the fastest moving tract of land

on the planet. Geologists have

calculated that if it were to

fall into the ocean, it could

trigger an Earthquake up to

magnitude seven and unleash a

colossal tsunami. All the cities

of Hawaii would be swept away as

a mammoth wave races towards the

California coast.

Investigators have discovered

why Hawaii is disappearing.

Sonar maps reveal the islands

are sliding off a swollen

section of the Earth's crust.

Kauai's crumbling landscape

reveals an inherent flaw in the

islands. They are made of the

hardest rock on Earth, but

exposed to water, they rapidly

break down. And Molokai's

dramatic cliffs, shorn away

overnight, are evidence of

catastrophic landslides.

Sinking, eroding and crashing

into the Pacific, eventually,

even the Big Island will be

just another underwater mountain

in the long chain hidden beneath

the waves. But the story of

Hawaii is far from over.

Rumblings from under the sea

tell scientists a new monster

may be rising from the waves.

Now they must venture into one

of the most hostile environments

on Earth, where fire meets

water.

The story of Hawaii is an

incredible tale of giant

volcanoes, unimaginable

catastrophe and vanishing

islands, but it doesn't end

here. Because, only 20 miles off

the Big Island's beaches,

something strange is stirring in

the depths.

In the 1950s, sea floor surveys

revealed that an underwater

volcano sat right on the

flanks of the Big Island.

Geologists were intrigued by

this giant seamount rising up

two miles from the ocean floor,

and named it Loihi. Scientists

were desperate to learn more.

but it wasn't until 40 years

later, when the technology

became available, that they

were able to dive down and

investigate the seamount.

>> (man) Scientists were very

interested to go down and

actually see what the situation

was, so they took the research

submarine Alvin, which is the

very famous three-person sub

that found the Titanic, and they

went down to the seamount and

found that there was a huge

pile of volcanic rocks that were

all freshly broken. And here's a

sample, this is a very heavy

rock, and it's a top of a pillow

lava.

>> Pillow lava was evidence of a

very recent eruption.

Scientists had believed Loihi to

be an ancient volcano, extinct

for thousands of years. But this

discovery called for some

radical rethinking. Could Loihi

be alive and erupting? Experts

struggled for 11 years to find

indisputable proof, mapping the

seamount extensively and taking

thounds of samples, until,

finally, they came across the

piece of evidence they had been

searching for.

>> Now it wasn't until 1996

that, really, the smoking gun

was discovered.

In October that year, there was

a huge number of seismic events

occurring that the people at the

volcano observatory discovered,

but they quickly realized that

the source of the seismic

activity was not on the island

here, it was offshore. They did

the best estimates they could

and it all pointed to this

seamount off the south

end of the Big Island.

>> This swarm of earthquakes

coming from Loihi were the

largest number ever recorded

from any Hawaiian volcano.

Scientists knew they were on the

verge of an incredible

discovery. Desperate to witness

the action as it happened,

scientists rushed to the heart

of the activity.

>> The trick was to get out

there while the eruption was

occurring.

So we went out there, there was

a tremendous amount of seismic

activity. From the ship you

could actually hear the noise of

the earthquake.

>> Venturing into the unknown, a

team from the University of

Hawaii dived 3,000 feet down

into this dangerous and

unpredictable environment.

>> Everywhere you could see were

mounds of broken up rock.

In this murky water was this

precipice. The top of the

Seamount had suddenly collapsed

to create this pit crater that

was hundreds of feet across and

hundreds of feet deep, and this

was the first evidence for

really active volcanic activity.

>> Experts had just missed one

of the most violent eruptions

Hawaii had ever seen, but, as

the dust settled, they were able

to survey the aftermath.

Lava had poured out of the

volcano, draining the summit and

causing it to collapse.

The team finally had proof that

Loihi was an active volcano,

which will continue to erupt and

grow until it forms a new

Island, the next in the Hawaiian

Chain.

>> The assumption was there had

to be another volcano coming up

one of these days. No one

knew whether that was gonna

happen in our lifetime or not,

but it's very rewarding for the

scientists to realize that now

the next volcano in the sequence

has been discovered - Loihi is

apparently it.

>> As lava continues to spew

from its submerged summit, Loihi

will build until it rises out of

the Pacific. The Pacific plate

will shift, carrying the Big

Island off the hotspot, and

Loihi will take its place at the

head of the Hawaiian chain.

Experts had studied the ancient

Islands of Hawaii for hundreds

of years, theorizing about how

they were created. But they

never imagined they would have

the opportunity to witness it

for themselves.

>> Loihi provides us with a real

unique laboratory, it gives us a

window back into the past.

This is our one chance to see

how it worked before the islands

reached the surface.

>> Reviewing all the evidence,

investigators finally understand

how the Hawaiian chain was

created. Gravity readings taken

in the 1930s show that the Big

Island is 140 times bigger than

Mount Everest. Further

investigation reveals that it is

made entirely from basalt lava

from five volcanoes. Rocks

created deep underground are

found within the lava and show

the island's volcanoes are

fueled by something from deep

within the Earth, a mantle

plume. But high levels of iron

in Hawaii's basalt lava cause

the islands to crumble. And the

steep cliffs of Molokai are

evidence of mega landslides.

Underwater lava is proof that a

new volcano is stirring - the

next island in the chain that

will eventually emerge from

beneath the waves.

Hawaii's dramatic cycle of birth

and death is more than just a

geological wonder. It's

transformed geologists'

understanding of the entire

planet.

On Hawaii we can see for ourselves

how the Earth is made.

-- Sync, corrected by elderman -- -- for MY-SUBS.com --