NARRATOR: 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. [dramatic music] [peaceful piano music] 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,
on Thingvellir plain. This broad, inland valley runs
through the center of Iceland. Giant cracks scar
the valley floor, leaving this unusual
landscape behind. [suspenseful music] 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. NARRATOR: 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 landmasses
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 on the land. And it splits the
North American Plate on this side from the
Eurasian Plate at 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. NARRATOR: 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
Thingvellir 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 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. NARRATOR: The investigation
into how Iceland is growing has revealed cracks on
the Thingvellir plain are widening at a rate
of one 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. [majestic music] NARRATOR: 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. [lava erupting] 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 3D
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. NARRATOR: His scan reveals a
giant crack or fissure running right through the
center of the volcano, similar to those found in
the Thingvellir 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. [dramatic music] 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 genealogical 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 surface. And to me, this is
really exciting, because you can see very large
volumes of erupted material produced over very
short amounts of time. And Hekla is a beautiful
place to study that. NARRATOR: 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 near the surface. NARRATOR: 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 caesium, 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 shock waves 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. Now 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 molten
material beneath the surface. NARRATOR: 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 hot material, including molten rock, magma,
that stream up to the surface from deep within the Earth. NARRATOR: 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 champagne bottle. NARRATOR: The removal
of so much pressure makes the rock melt
into liquid magma. Now 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. [ethereal music] NARRATOR: 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 14, 1963, off
the south coast of Iceland, the world watched
an action replay of Iceland's spectacular birth. [eruption crashes] 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 get
a chance to go out and see it up close and actually look
at the geology, it's just-- 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. NARRATOR: 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 millennia. In about 9 and 1/2 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. NARRATOR: 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
landmass, 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 volcano. 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 10% of
the island all year round. And in the middle of the country
lies Europe's biggest ice cap, the mighty Vatnajokull. Over 3,000 square miles in
size, Vatnajokull is so large, it even has its own
climatic conditions. Up to 2/3 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 discovered 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 analyze the data and discover just how far
the glacier has moved. NARRATOR: 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 in 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. NARRATOR: Vatnajokull is
one of the largest ice caps 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 ice, material trapped inside the ice 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. NARRATOR: 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. 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
erosive power of a glacier. NARRATOR: 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
1 and 1/2 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 carved the fjords put out the fires that created Iceland? [dramatic music] 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. It would have inundated
this entire valley. NARRATOR: 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 Vatnajokull
and is hunting for clues. With such a huge area to cover,
Dr. Roberts takes to the air. [engine roars] 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 ice has been formed as a pocket
of water has drained from beneath the
base of the ice cap. The beautiful
concentric crevasses that you see on the ice surface
are formed as the ice has slowly crept into the
hollow that's been created as the water has drained away. NARRATOR: Beneath the ice, a
dynamic process is happening. 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 Vatnajokull, this massive volcano violently
erupts every 10 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 underwater. The flood itself reached
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. NARRATOR: The sheer
force of the water carried icebergs the size
of four-story 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 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. NARRATOR: 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. NARRATOR: 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. 75% of the livestock
died, plunging Iceland into a great famine which
killed 10,000 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. The North Sea along
the coast of Holland froze, so people skated between
villages along the coast. There was ice on
Mississippi down by New Orleans in that winter. NARRATOR: For many years, it
was thought the Laki eruption and these climatic
events 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. [eruption booms] He discovered that the
eruption started with a bang on the morning of June 8, 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 10 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. [hammer chipping] 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. NARRATOR: 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're growing, they will encapsulate
pristine magma and bring it up to the surface. NARRATOR: 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 sulfur dioxide. And because there was
so much lava here, it would have released
enormous amounts. A staggering 100 million
tons of sulfur 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 sulfur
dioxide, which rose high into the air. Mixing with water, it
created a sulfuric 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 led 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 cloud in India. Also, this change in
atmosphere 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. NARRATOR: It is
estimated that Laki killed over 2 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 sulfur 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 volcano's 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 Vatnajokull glacier for the last 10 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. 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. NARRATOR: Iceland's
glaciers are melting at an unprecedented rate. With 5% of Iceland's ice caps
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 11,000
or 12,000 years ago, you started to see quite rapid
melting of glaciers in Iceland and elsewhere. And that triggered a
recognizable increase in volcanic
activity, because you were removing this large mass
of ice very, very quickly. NARRATOR: 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 bottle of champagne. Now if you have a very heavy
weight on top of a volcano, if there's a heavy
mass of water or ice, that can help suppress
eruptive activity. NARRATOR: 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. NARRATOR: Iceland's glaciers
are melting rapidly. This has led
scientists to believe that a devastating eruption
on the scale of Laki could happen again. 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. NARRATOR: The
investigation has revealed how the vast and violent
island of Iceland was formed. Cracks in the Thingvellir
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
sulfur 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. [eruption booms] [dramatic music] 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.
