>> 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 addic7ed.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 addic7ed.com --