>> Earth, a 4.5 billion year
old planet, still evolving.
As continents shift and clash,
volcanoes erupt, and glaciers
grow and recede, the Earth's
crust is carved in numerous
and fascinating ways, leaving
a trail of geological
mysteries behind. In this
episode, Iceland, the world's
largest volcanic island, is
explored. This barren and
alien landscape generates one
third of the world's lava.
Steam billows from the ground
and boiling water is thrust
into the air.
It's a land of violent
extremes where fire meets its
nemesis, ice, and where
clues to understanding
Iceland's formation also
provide a window into the
formation of the Earth itself.
S01x11 Iceland Volcano Original Air Date on April 28, 2009
-- Sync, corrected by elderman -- -- for www.addic7ed.com --
In the middle of the north
Atlantic Ocean lies Iceland, a
lone island, only 300 miles
wide. A volcanic hotbed, it
holds some of the most diverse
geological wonders known to
mankind. To understand how it
formed and the dynamic forces
that are shaping this land,
scientists are scouring the
strange landscape for clues.
And the investigation starts
here, in the southwest of
Iceland - the Thingvillir
plain. This broad inland
valley runs through the center
of Iceland. Giant cracks scar
the valley floor, leaving this
unusual landscape behind.
Geologist Mike Poland believes
they're a major clue in the
mystery of Iceland's
formation.
>> I'm standing in a really
spectacular place.
There's evidence for volcanic
activity all around. This
valley is covered in lava and
the plain is being ripped
apart. Everywhere I look,
there's massive tears in the
ground, like this one right
here.
This crack is getting bigger
and bigger every year.
In fact, this entire valley is
spreading apart at about the
same rate that fingernails
grow. Now, imagine the forces
that must be involved to rip
the land apart like this.
>> Something powerful is
spreading this valley at a
rate of one inch a year.
A force so immense, it's
pulling the entire country
apart.
But what force on Earth
could have such power?
In 1912, German climatologist
Alfred Wegener found an
essential clue. Browsing
through maps, he noticed that
the great land masses of the
Americas and Eurasia appeared
to fit together. This
observation led Wegener
to propose a radical new
theory, that these great
continents had once been
joined together. So some
unseen force must have
pushed them apart, allowing
water to rush into the space
between them, creating the
Atlantic Ocean.
It was inspired detective work
and a major step forward in
the search for what was
pulling Iceland apart.
But with no method to prove
such a force existed,
Wegener's theory was ignored
for the next 40 years.
Then, in 1946, new evidence
was discovered to support
Wegener's ideas.
The US Navy, using a
technology called sonar
imaging, mapped the Atlantic
Ocean floor for the first
time. The pictures revealed a
10,000-mile network of
underwater mountains,
separated by a giant tear
which passes through the
center of the Atlantic.
Scientists call this the
Mid-Atlantic Ridge.
This huge tear through the
Earth's crust is the boundary
between the American and
Eurasian plates, and the tear
runs right through the center
of Iceland.
>> I'm actually standing on
what's essentially the ocean
floor where the Mid-Atlantic
Ridge comes onto land.
And it splits the North
American plate on this side
from the Eurasian plate on
this side. And the
Mid-Atlantic Ridge starts way
south down by Antarctica,
comes all the way up through
the Atlantic and splits this
country right in two.
>> Scientists suspected this
was pushing the continents,
and Iceland, apart.
They came up with a theory.
Deep below the ocean,
convection currents of molten
rock tear open the Earth's
crust, allowing magma to seep
up and push the continents
apart. But there was a
problem. It was so deep,
scientists had no way of
proving whether magma was
seeping through the crust at
the center of the ridge.
Until, in 1974, Alvin, a
human-operated submersible,
was launched by the Woods Hole
Oceanographic Institute.
With its ability to withstand
deep sea pressures, scientists
could finally travel down to
the depths needed to reach the
Mid-Atlantic Ridge.
It was by examining the tear
that runs through the center
of this ridge that they
spotted the evidence they'd
been looking for - hot
volcanic gases billowing into
the ocean. Finding this told
them that the Mid-Atlantic Ridge
was highly volcanic and, like
a giant wedge, was capable of
spreading great land masses
apart.
Iceland's cracked Thingvillir
valley is a continuation of
the Mid-Atlantic Ridge.
The same process that's
pushing America further away
from Europe is happening here
on land.
Finally, here was a force
powerful enough to explain why
the cracks are getting wider,
and Iceland is getting bigger.
As the ridge continues to spread
it's going to add, more and more
land to Iceland.
So, in a way Iceland
will start getting longer and longer
uh, in an east-west sense
as the plates spread
apart from one another.
So in a way, Iceland
is not getting torn apart
so much as it's getting built.
The investigation into how
Iceland is growing
has revealed
cracks on the Thingvillir Plain
are widening at a rate of
1 inch a year.
And hot gases prove
that this spreading force
is volcanic.
forming the Mid-Atlantic Ridge
which cuts right through Iceland.
Scientists concluded it's this
that's widening the country.
Convection currents of hot
rock pull the Mid-Atlantic
Ridge apart. Magma surges up
to fill the cracks and, as it
approaches the surface, it
cools, hardens and forms new
land. Like a conveyor belt, it
continually pushes Iceland
apart.
But something didn't add up.
Why wasn't Iceland at the
bottom of the ocean like the
rest of the Mid-Atlantic
Ridge? There's something
strange about the amount of
volcanic activity on this
island.
>> This is not a normal section
of the Mid-Atlantic Ridge.
There's a tremendous amount
of volcanism that's happening
in this part of the ridge.
as opposed to the ridge
that's off in the Atlantic Ocean.
>> The hunt is now on to
discover how Iceland rose a
mile and a half off the ocean
floor and became the biggest
volcanic island in the world.
Iceland. There are more active
volcanoes concentrated here
than anywhere else on the
planet.
Geologists are searching for
what has helped push Iceland
off the ocean floor and lights
the fiery volcanoes that rage
across this barren land.
On the hunt for clues, the
investigation heads to one of
Iceland's most active
volcanoes, Hekla, known
locally as the Gateway to
Hell. Like all active
volcanoes in Iceland, Hekla
sits alongside the
Mid-Atlantic Ridge.
Volcanologist Dr.
Pete La Femina is taking a
high-resolution scan of the
volcano to see if its geology
hides any clues about its
inner workings.
>> This is a terrestrial laser
scanner, and the laser
produces a 3-D image of the
Earth's surface, and that
allows us to see parts of
Hekla volcano here that we
can't see with the naked eye.
>> His scan reveals a giant
crack, or fissure, running
right through the center of
the volcano, similar to those
found in the Thingvillir
valley.
But this fissure doesn't just
span the width of the volcano,
it extends either side, along
a five-mile tear in the Earth.
It's this tear that's key to
understanding how Iceland's
volcanoes erupt.
When Hekla erupted in the year
2000, it wasn't just the
volcanic cone that exploded.
The earth actually ripped open
along the entire five-mile
length of the fissure, a
weakness created by the
stretching along the
Mid-Atlantic Ridge.
In the geological world, these
are known as fissure
eruptions. Forced open by the
sheer volume of magma pushing
up from below, the tear spewed
out a terrifying 750 million
cubic feet of molten rock an
hour, flooding the land with
lava. These fissure eruptions
are so huge they can change
the landscape drastically in a
matter of days, leaving behind
mountains like these.
>> You can see to the north
here where the Earth's surface
actually opened up during the
fissure eruption and lava
erupted out. This fissure
starts to the north and
extends eight kilometers
through Hekla volcano here.
The sheer volume of magma
produced can be seen very well
here at Hekla volcano,
especially with these lava
flows that have draped the
land's surface. And, to me,
this is really exciting
because you can see very large
volumes of eruptive material
produced over very short
amounts of time. And Hekla
is--is a beautiful place to
study that.
>> But what is creating the
vast quantities of lava that
are forced out during these
eruptions? For many years, the
answer remained elusive, until
geologists found incriminating
evidence locked inside the
rocks.
>> The composition of the
rocks here in Iceland is quite
different than we see in
other places. By taking this
rock back to the lab, we can
get a very good idea of under
what conditions it formed,
whether it formed deep within
the Earth or--or near the
surface.
>> This rock was once molten
lava which erupted from one of
Iceland's volcanoes.
Analysis of the chemicals in
the rock revealed unusually
high concentrations of rare
Earth elements lanthanum and
cesium, chemicals which are
only found in magma with a
very deep origin.
It's the breakthrough
scientists had been searching
for. It was evidence that
another, much deeper, heat
source was combining with the
Mid-Atlantic Ridge to power
the volcanoes of Iceland.
The rock evidence suggested
this second force lay hidden
from view, deep beneath
Iceland's surface, but it is
possible to get a glimpse of
what's happening down there.
Scientists monitor the seismic
waves triggered by earthquakes
all over the world.
As the Earth's plates move,
they release shockwaves
called seismic waves that pass
through the Earth's crust.
These travel at a steady
speed, unless they hit a
region of hot rock, then they
slow down.
>> POLAND: Now, as seismic
waves arrive in Iceland,
they're traveling very slowly
through the subsurface, and
this is somewhat unique to
Iceland and a few other places
in the world. It tells us that
there's a very hot column of
rock, perhaps even some--some
molten material beneath the
surface.
>> These massive columns, or
plumes, are known as hotspots,
and are not unique to Iceland.
They are found beneath certain
volcanic areas in the world,
like Hawaii and Yellowstone.
>> Hotspots are these
unwavering plumes of--of hot
material, including molten
rock, magma, that stream up to
the surface from deep within
the Earth.
>> The scientists finally had
a snapshot of the second force
that was helping to create
Iceland. The hotspot that lies
beneath the island is almost
100 miles wide and 400 miles
deep. It channels rock slowly
upwards at temperatures over
1,700 degrees Fahrenheit.
It pushes against the crust,
heating the land from below
and forcing magma up onto the
surface as lava.
The investigation has
identified the two colossal
forces that built Iceland -
the Mid-Atlantic Ridge and the
deeper Icelandic hotspot.
Millions of years ago, the
Mid-Atlantic Ridge drifted
eastwards, creeping towards
the fixed Icelandic hotspot.
Finally, they met and have
been locked together in a
deadly partnership ever since.
The result, a truly formidable
volcanic beast, capable of
creating magma on a monumental
scale.
>> As the mid-ocean ridge
pulls apart, there's
decompression of the material
underneath it and that creates
melting. Decompression is
simply removing the pressure
from a pile of rock. It's much
like opening a can of soda or
popping the cork off of a--
a champagne bottle.
>> The removal of so much
pressure makes the rock melt
into liquid magma.
>> The hotspot is transporting
heat directly from the
interior of the Earth to the
surface, which also creates
melting. So this combination
of decompression of existing
rock beneath the surface and
the direct transport of heat
from the center of the Earth
create a huge amount of magma.
>> This incredible meeting of
the Mid-Atlantic Ridge and
hotspot began to build the
island beneath the waves,
pushing it upwards and giving
birth to Iceland.
Scientists have dated the
island's emergence to 20
million years ago, but could
only imagine what this might
have looked like. But on
November 14th 1963, off the
south coast of Iceland, the
world watched an action
replay of Iceland's
spectacular birth.
A column of rock and ash
blasted out of the ocean,
18,000 feet into the sky, so
high it could be seen 70 miles
away in Iceland's capital
city, Reykjavik.
A new island was forming right
in front of the world's eyes.
Scientists called it Surtsey,
after the Norse god of fire,
Surtr.
Located 20 miles off the
mainland, the small island of
Surtsey is now a magnet for
geologists. It offers a wealth
of forensic evidence for Dr.
La Femina, who is
investigating how Iceland
first formed.
It's amazing to see Surtsey
for the first time.
I've seen pictures.
I've seen aerial photographs.
But to actually be here
and a chance to, uh
go out and see it
up close and actually
look at the geology
it's just, awe inspiring.
This type of eruption that
formed Surtsey has now been
named after Surtsey, we call
them Surtseyan eruptions, and
they're very, very explosive.
The interaction of hot magma
or lava with the ocean causes
these very steam-rich and
highly explosive eruptions of
ash and water.
>> When scientists first
stepped foot on the island in
the summer of '64, they found
it hard to believe that this
was an island whose age was
measured in months, not
mimillennia.
>> In about nine and a half
months, this whole volcanic
cone built up. In addition,
lava flows came out of the
volcanic center here, and
we're seeing those, these nice
black cliffs in front of us.
>> Now geologists had an
insight into how early Iceland
might have formed. In only 20
million years, Iceland grew
from a tiny island into a
40,000 square mile land mass
as big as the state of
Kentucky. The forces that
power Iceland's volcanoes have
been revealed. Cracks along
Hekla volcano unleash gigantic
fissure eruptions. And rare
chemicals in the rock prove
that these eruptions were
fueled by two separate forces,
the Mid-Atlantic Ridge and the
hotspot. Iceland grew to
become the world's largest
volcanic island. But volcanism
alone doesn't explain how the
land of Iceland was formed.
The investigation will unearth
another, equally dramatic,
force that sculpted the
distinctive shape of the
Iceland we know today.
A force which would challenge
the might of Iceland's
volcanoes.
If Iceland was formed by fire
alone, it should look like
other volcanic islands such as
Hawaii or Tahiti, but
something else was at work
here to transform this island
into the distinctive shape it
is today. Its shape is another
clue to Iceland's formation.
An extraordinary force
indented Iceland's northern
coastline, burrowing deep
fjords which extended far
inland. But what colossal
force could cause such a
dramatic change to Iceland's
volcanic landscape? There's an
obvious suspect that's found
scattered across the island -
ice. As its name suggests,
Iceland has a long history of
being covered in ice
like this.
Today it covers ten percent
of the island, all year
round. And in the middle of
the country lies Europe's
biggest icecap, the mighty
Vatnajökull. Over 3,000 square
miles in size, Vatnajökull is
so large it even has its own
climatic conditions.
Up to two thirds of a mile
thick, it squashes the land
like a giant slab of rock, and
at its edges, great tongues of
ice flow out through deep
valleys.
Glacier expert Dr. Matthew
Roberts is investigating how
ice can gouge out solid rock,
and discover the role it has
played in Iceland's past.
>> This is a GPS receiver,
just like in car satellite
navigation. It's used here to
measure glacier movement.
This will be left on the ice
surface for a few days and
then I'll come back and I'll
analyze the data and discover
just how far the glacier has
moved.
>> Dr. Roberts' data reveals
that this whole glacier is
sliding forward at an
astounding rate of two feet
per day.
>> This is an amazing,
ever-changing environment. The
ice around me is like an icy
sea that's been frozen in
place. As the ice flows out of
the confines of the valley, it
expands and spreads to occupy
a greater area. Now, as it
expands, crevasses form, and
large depressions just like
the one here. Here's a smaller
crevasse that's formed.
Occasionally, when these
crevasses open, as they begin
to open, sounds can be heard.
Also, the glacier occasionally
makes a groaning sound. This
is all signs that the glacier
is alive and moving forward
very slowly.
>> Vatnajökull is one of the
largest icecaps in the
northern hemisphere.
Flowing down the valleys, the
great mass of ice bears down
with the weight of 100 tons
per square foot. Dr. Roberts
believes this moving giant is
a force capable of eroding
solid rock, and he's found
crucial evidence to prove it.
>> This is an excellent
example of the power of
glacial erosion. This boulder
would have been trapped
beneath the base of the ice,
and as the ice flowed over the
surface of it, it would have
progressively eroded the
surface of the boulder to
produce these very distinctive
marks called striations in its
surface. We can even tell the
direction in which the ice was
flowing. If I take a rock, I
can illustrate this. Imagine
this is the base of the--of
the ice and material trapped
inside the ice is being
dragged across as the glacier
moved to produce these
very distinctive marks in the
surface. This is just like
sandpaper over wood. The same
erosive effect.
>> The erosive process that's
happening on this boulder is
the same process that's
happening on a much larger
scale along the surface of
these valleys.
>> ROBERTS: The glacier is
responsible for literally
carving the landscape,
producing very distinctive
troughs and basins which were
formerly infilled with solid
rock. This really testifies to
the--the erosive power of--of
a glacier.
>> The ancient fjords on the
north coast are the same deep
basin shape, which means they
must once have been filled
with ice.
Scientists now know that,
around one and a hf million
years ago, changes in the
Earth's orbit, and the tilt of
its axis, began to cool the
planet. An enormous ice sheet
descended from the north and
shrouded Iceland in a cloak of
ice. As the ice advanced and
retreated, it carved out deep
fjords and indented Iceland's
northern coastline. Ice was a
formidable force in Iceland,
and many volcanoes lay
entombed beneath it. Fire and
ice were now locked in a
titanic battle of supremacy.
Would the giant ice sheets
that cbrved the fjords put out
the fires that created
Iceland?
The first clue lies in this
ancient valley, five miles
west of the glacier.
The valley floor is strewn
with hundreds of giant
boulders, but it's how they
got here that interests Dr.
Roberts.
>> These boulders provide a
lot of insight into how this
landscape was formed.
The boulders are clustered
together and, interestingly,
these boulders are rounded,
which shows that they've been
rolling. Now, the boulders
have been brought together by
some dynamical force. You can
also see smaller boulders
trapped in the center. And
It's quite clear that flowing
water is the cause of this.
But this wouldn't have been
water in the stream that we
see in the background.
This would have been water
produced by a much larger,
faster flow that would have
inundated this entire valley.
>> Dr. Roberts has an
extraordinary theory about
what happened here. In ancient
times, a cataclysmic flood 100
feet high cut through this
valley. It was so powerful
that it rolled these giant
boulders like pebbles in a
stream, before dumping them on
the landscape.
But what could create such a
colossal flow of water?
Dr. Roberts suspects the flood
came from the mighty
Vatnajökull glacier and is
hunting for clues.
With such a huge area to
cover, Dr. Roberts takes to
the air.
His investigation leads him to
a crucial piece of evidence -
this strange bowl-like
depression on the surface of
the ice.
>> This is an amazing
location. This giant
depression in the--in the ice
has been formed as a pocket of
water has drained from beneath
the base of the icecap. The
beautiful concentric crevasses
that you see on the ice
surface have formed as the ice
has slowly crept into the
hollow that's been created as
the water has drained away.
>> Beneath the ice, a dynamic
process is happeni. Hot
magma and steam are melting
the glacier from underneath.
The meltwater collects in a
huge ice basin, at the top of
the volcano. The basin slowly
fills, but as it does, the
surrounding ice becomes
unstable. Cracks appear in the
ice basin and, as the hot
water drains away, it forms a
tunnel which channels the
water to the edge of the
glacier. This would suggest
that volcanic eruptions still
happen, even under the
enormous weight of ice.
Is this process the key to
explaining the ancient
cataclysmic flood? To answer
this we must go to one of
Iceland's largest volcanoes,
Grimsvotn. Lying entombed
beneath the ice in the heart
of Vatnajökull, this massive
volcano violently erupts every
ten years. Here, fire and ice
spectacularly collide, with
Iceland's volcanoes emerging
victorious. Ice cannot
suppress the invincible power
of Iceland's volcanoes, which
have now found a new way to
vent their anger. During a
huge eruption like this,
Grimsvotn can melt enough ice
to fill America's largest
man-made reservoir, Lake Mead.
But this vast volume of water
cannot be held back by the ice
for long and leads inevitably
to a massive glacial flood.
Such a force of nature struck
Iceland in 1996, with
devastating consequences, the
floodwater taking out
everything in its path.
Bridges were torn down and
swept away, and the highway
was submerged under water.
>> The flood itself reached
a--a peak discharge of over
1.8 million cubic feet per
second, that's a remarkable
discharge, equivalent to the
summertime discharge of the
River Amazon. Imagine that
sort of condition over a
relatively small area.
>> The sheer force of the
water carried icebergs the
size of four-storey buildings.
It's floods like these that
can change the landscape in a
matter of days.
>> The erosive power of the
flowing water can result in
tremendous amounts of--of rock
being eroded, literally being
fractured away by the high
water pressure that's being
created. So, literally, a
landscape can form before your
eyes during a very severe
glacial flood.
>> The story of Iceland's
bizarre landscape is taking
shape. Striations on rock
prove that ice is a formidable
force that carved out
Iceland's unique coastline.
Boulders strewn in an empty
valley reveal cataclysmic
floods of the past.
And depressions in the ice
confirm that Iceland's
volcanoes could not be
suppressed. But 12,000 years
ago, the great ice sheets
retreated, and Iceland was
liberated from their wintry
grip. Now, the effects of
Iceland's volcanoes would be
felt on a global scale.
For thousands of years,
Iceland's volcanoes were
locked in a titanic battle
with ice, but then, 12,000
years ago, the giant ice
sheets finally retreated.
This would open a new chapter
in Iceland's volcanic history,
as they were now free to wreak
havoc. But what effect would
this have on Iceland and its
surroundings? One of the most
dramatic effects can be found
in the south central region of
the island. This alien
landscape is known as Laki.
A row of strange craters and
solidified lava flows that
have bubbled up from a huge
tear in the earth. A massive
fissure eruption, it stretches
for an astounding 16 miles
across the landscape.
Volcanologist Dr. Thor
Thordarson is investigating
Laki, the site of one of the
greatest eruptions in recent
history, one which would have
devastating effects worldwide.
>> The Laki fissures which
extend from here in the
southwest continue here
through the landscape as a row
of cones, up here, through
Mount Laki, which was split
into two during the eruption,
and continue further to the
northeast all the way to the
margins of the glaciers here.
>> Eyewitness accounts
accurately date the eruption
to 1783. This was one of the
most disastrous years in
Icelandic history. Fallout
from the eruption caused
harvests all over the island
to fail and 75 percent of the
livestock died, plunging
Iceland into a great famine
which killed ten thousand
people. But mysteriously, at
the same time, the rest of the
northern hemisphere reported
freakishly cold weather.
Averaging 2.3 degrees
Fahrenheit below normal, the
northern hemisphere froze
over.
>> THORDARSON: The North Sea
along the coast of Holland
froze, so people skated
between villages along the
coast. There was ice on the
Mississippi down by New
Orleans in that winter.
>> For many years, it was
thought the Laki eruption and
these climatic ents were
unrelated, but advances in
geology found it wasn't just a
bizarre coincidence.
Comparing eyewitness accounts
with the geological remains,
Dr. Thordarson has
reconstructed what happened.
He discovered that the
eruption started with a bang
on the morning of June 8th
1783. It sent rocks flying
high into the air and ripped
the earth open along a
one-mile tear. But this was
just the beginning. Three days
later, a second eruption
ripped open, then a third,
fourth, fifth. In total, the
earth unzipped along ten vast
tears in the crust, erupting
lava continuously, for over
eight months. The mammoth
amounts of lava that poured
out of the ground here would
have buried Manhattan to a
depth of 830 feet. But how an
eruption on this small, remote
island could cause climatic
chaos thousands of miles away
remained a mystery.
The evidence that would link
Laki with this worldwide
catastrophe was locked inside
these boulders.
>> The story is in the rocks.
This rock here is part of the
material, the magma that came
out during the eruption. These
holes are called bubbles.
And they form as the magma
rises from deep within the
ground and approaches the
surface, and it really starts
to boil. The gas which is
dissolved in the magma at
depth goes into the bubbles,
then it escapes into the
atmosphere.
>> When this "bubble rock"
erupted onto the surface, it
would have poured gas out into
the Icelandic atmosphere.
Could this gas have caused
climatic chaos across the
globe?
The identity of this gas can
be found in the microscopic
structure of the rock.
>> If you look closely at this
rock, you can see a lot of
white specks. These little
white specks are crystals who
grow in the magma at depth.
Sometimes these crystals, as
they grow, they will
encapsulate pristine magma and
bring it up to the surface.
>> Like time capsules, the
white crystals contain
untouched magma from deep in
the Earth, locked away since
1783. Dr. Thordarson has
analyzed this magma and found
it to contain poisonous
sulphur dioxide. And because
there was so much lava here,
it would have released
enormous amounts. A staggering
100 million tons of sulphur
dioxide gas was pumped into
the atmosphere.
But how could gases released
from Laki cause bitterly cold
weather across the globe?
The answer lay in accounts of
a thick red fog reported over
Iceland in June 1783. Within a
few weeks, it had been blown
over London and Paris, and by
July it had dispersed across
the entire northern
hemisphere. Scientists now
know that the red fog was
caused by the sulphur dioxide
which rose high into the air.
Mixing with water, it created
a sulphuric acid haze. The
haze blocked out the sun and
it sent temperatures
plummeting. As a result, the
northern hemisphere endured
three bitterly cold winters,
which brought spring floods,
famine and widespread poverty
to Europe. Some historians
have long believed that these
climatic conditions triggered
social and political unrest
which le!d to the French
Revolution in 1789. But
scientists now suspect Laki
had ramifications even further
afield. The cold temperatures
in the north changed air
currents in the south, causing
dramatic climate changes.
India was hit by a terrible
drought.
>> People say that more than
half a million people died
from the drought in India.
Also, this change in
atmospheric circulation caused
a very cold summer in Japan.
It was cold and wet, the rice
harvest failed and the result
was the greatest famine in
Japanese history.
>> It is estimated that Laki
killed over two million people
worldwide and was one of the
most devastating volcanic
eruptions in the history of
mankind.
The evidence has proven that
Iceland's recent volcanic
history has had a devastating
effect on the island, and the
rest of the world. Enormous
lava fields reveal that Laki
was a gigantic eruption.
Bubbles in the rock indicate
that huge volumes of gas were
released from Laki. The white
crystals reveal that this gas
was poisonous sulphur dioxide.
Evidence that Iceland's
volcanoes caused climatic
mayhem across the globe.
But eruptions like Laki may
not be confined to the past.
Some believe that the balance
between fire and ice is
shifting and has the potential
to propel Iceland into another
hell on Earth.
The evidence is mounting that
Iceland has the potential to
be the most lethal island on
the planet. A fearsome
volcanic force lies beneath
it, creating powerful
volcanoes capable of
generating gigantic lava flows
and altering global climates.
Yet many of Iceland's
volcanoes are covered in
glaciers. Fire and ice are
held in a delicate balance.
Scientists fear if this
balance were tipped in the
volcanoes' favor, Iceland
could become even deadlier.
If the remaining ice were to
melt, what effect would it
have on the activity of
Iceland's volcanoes? The first
clue in the investigation lies
in these innocuous looking
piles of rock and rubble.
They're found all over
Iceland, and yet these rocks
don't come from a volcano.
They're moraines, the
geological term for rock piles
deposited at the mouth of a
glacier. These deposits are
evidence that the glaciers are
shrinking. Year by year, the
glacier has melted and
retreated back up the valley,
leaving a moraine like this
behind.
Dr. Roberts has studied the
Vatnajökull glacier for the
last ten years and has noticed
this dramatic trend.
>> The glacier has retreated
at a remarkable rate. Since
I've been visiting the area,
I've seen tremendous changes.
The ice has retreated annually
at a rate of about 200 feet
per year. This lake over here
used to be filled with ice.
I've seen the ice
progressively melt, this
moraine has formed and this
whole valley has become almost
bare. Maybe in the next 20
years, this whole glacier will
disappear and a lake will form
in the valley.
>> Iceland's glaciers are
melting at an unprecedented
rate. With five percent of
Iceland's icecaps melting in
the last 40 years, the
question that scientists are
keen to understand is what
effect this rapid melting will
have on the volcanoes that lie
beneath. The only other time
that glaciers have melted this
quickly is when Iceland came
out of the last Ice Age. But
what can past events tell us
about the future? Geologist
Professor Bill McGuire is
investigating how volcanic
activity changed at the end of
the last Ice Age, and he's
unearthed some surprising
results.
>> Around about 11 or 12,000
years ago, you--you started to
see quite rapid melting of
glaciers in Iceland and
elsewhere, and that triggered
a--a recognizable increase in
volcanic activity because you
were removing this large mass
of ice very, very quickly.
>> The rapid melting of ice
kick-starts volcanic eruptions
beneath.
>> Volcanic eruptions are
triggered by the gas in the
magma, which expands to form
bubbles, and the bubbles drive
the eruption. It's rather like
taking the cork out of a--a
bottle of champagne. Now, if
you have a very heavy weight
on top of a--a volcano, if
there's a heavy mass of water
or ice, that can help suppress
eruptive activity.
>> But when ice melts quickly,
this downward pressure is
suddenly released, and that's
when the trouble starts.
>> As the ice melts, so the
pressure on the magma
underneath is reduced, the gas
in the magma can form bubbles,
they can coalesce and they can
eventually drive the magma
upwards towards the surface
and trigger either explosive
eruptions or effusions of lava
that can spread out over huge
distances.
>> Iceland's glaciers are
melting rapidly. This has led
scientists to believe that a
devastating eruption on the
scale of Laki could happen
again.
>> The question is when. These
are things that we have to
think about and try to prepare
ourselves to deal with if they
happen in our lifetime. Is it
possible that we can get
another eruption like this in
Iceland? Definitely.
>> The investigation has
revealed how the vast and
violent island of Iceland was
formed. Cracks in the
Thingvillir Plain and traces
of chemicals in the rocks
revealed how the Mid-Atlantic
Ridge and hotspot joined
forces to create a colossal
volcanic force.
Massive fissure
eruptions ripped the land
open. Hemorrhaging millions
of tons of lava, Iceland
rapidly formed. Deep northern
fjords were evidence that a
giant ice sheet eroded the
land and entombed the
volcanoes, locking fire and
ice in a titanic battle.
Boulders, strewn in an ancient
valley, revealed how fire
emerged victorious, unleashing
cataclysmic floods. And specks
of sulphur in the rocks showed
how Iceland's volcanoes have
the potential to cause global
destruction. Now glaciers,
melting above some of the
world's most deadly volcanoes,
are increasing the threat of
future eruptions.
Over the last 20 million
years, Iceland's almighty
volcanic force has created a
vast, alien landscape.
Volatile and unpredictable, it
may one day unleash a massive
eruption which could devastate
both Iceland and the wider world beyond.
-- Sync, corrected by elderman -- -- for www.addic7ed.com --