0:00:03 > 0:00:05Two years ago,
0:00:05 > 0:00:09an ash cloud from an Icelandic volcano paralysed Northern Europe.
0:00:09 > 0:00:13But was this just a freak event or could it happen again?
0:00:14 > 0:00:19I'm travelling to the source of the ash cloud to find out.
0:00:20 > 0:00:22I'll be meeting the scientists
0:00:22 > 0:00:26who are monitoring the biggest volcanic threats.
0:00:26 > 0:00:29I'll descend deep underground to discover
0:00:29 > 0:00:31the effects of tectonic activity.
0:00:33 > 0:00:36And I'll meet the people who live and work
0:00:36 > 0:00:40in the most volcanically active country on Earth.
0:00:42 > 0:00:45We may not have any active volcanoes in Britain,
0:00:45 > 0:00:47but we're not immune to their effects.
0:00:49 > 0:00:52What can we learn from Iceland about living with volcanoes?
0:01:13 > 0:01:15Here in Britain,
0:01:15 > 0:01:18we tend to think of large-scale natural disasters
0:01:18 > 0:01:21as something that happen in other countries
0:01:21 > 0:01:23less safe and benign than ours.
0:01:23 > 0:01:27But in 2010, something happened to remind us
0:01:27 > 0:01:30that we're not immune from the forces of nature.
0:01:30 > 0:01:35A volcano erupted over 1,000 miles away in Iceland,
0:01:35 > 0:01:39but in a matter of hours it brought our modern, high-tech world
0:01:39 > 0:01:40to a juddering halt.
0:01:51 > 0:01:54For the first time in British aviation history,
0:01:54 > 0:01:59all flights in and out of the UK have been cancelled.
0:01:59 > 0:02:03Ten million flights pass through European airspace every year.
0:02:03 > 0:02:08At Heathrow alone, they deal with over 1,000 planes a day.
0:02:08 > 0:02:10Air traffic controller Jonathan Astell was on duty
0:02:10 > 0:02:13the day the ash cloud arrived.
0:02:13 > 0:02:15We know that putting volcanic ash through an engine of an aircraft
0:02:15 > 0:02:18is a bad thing to do. In this case, it was very much like glass,
0:02:18 > 0:02:22which, if you throw a box full of bottles through an aircraft engine,
0:02:22 > 0:02:24that's not going to be good.
0:02:24 > 0:02:27It's going to melt, it's going to really do some serious damage.
0:02:27 > 0:02:29'In a matter of hours,
0:02:29 > 0:02:33'European aviation authorities were forced to shut the skies.'
0:02:33 > 0:02:35I've never worked so hard
0:02:35 > 0:02:37for so few aircraft flying. It was just incredible.
0:02:37 > 0:02:40And at one point it felt like it would never end.
0:02:48 > 0:02:53But not all Icelandic eruptions bring Europe to a standstill,
0:02:53 > 0:02:56so what was it that made this one so disruptive?
0:02:56 > 0:02:59And most importantly, could it happen again?
0:03:01 > 0:03:05To find out, I'm heading for the country where all this began.
0:03:07 > 0:03:09MUSIC: "Play Dead" by Bjork & David Arnold
0:03:29 > 0:03:33It's called "the Land of Fire and Ice,"
0:03:33 > 0:03:35and I was trying to avoid using that term,
0:03:35 > 0:03:40but when you're up here looking at it, that's exactly what it is.
0:03:43 > 0:03:46The scale of this landscape
0:03:46 > 0:03:48is just astonishing.
0:03:51 > 0:03:54Nature's had a field day on this island.
0:03:57 > 0:04:02I'm on my way to the site of the 2010 eruption
0:04:02 > 0:04:04to see what it looks like two years on.
0:04:07 > 0:04:09Well, this is it.
0:04:10 > 0:04:12This is the culprit.
0:04:12 > 0:04:14Eyjafjallajokull.
0:04:17 > 0:04:22We're flying directly around the crater now.
0:04:24 > 0:04:28You can smell the sulphur in the air.
0:04:30 > 0:04:31And it's strange.
0:04:31 > 0:04:34I thought that there would be somehow more evidence,
0:04:34 > 0:04:38that the landscape would still be blackened.
0:04:38 > 0:04:40I mean, there was tons and tons -
0:04:40 > 0:04:44untold amounts - of ash that poured out of this crater,
0:04:44 > 0:04:48and yet now there's so little sign of it up here.
0:04:51 > 0:04:55And it looks so benign and so beautiful now.
0:04:55 > 0:05:01A great shining, pure white glacier.
0:05:01 > 0:05:03It's just an incredible sight.
0:05:10 > 0:05:15The eruption was on a scale that we hadn't seen in living memory.
0:05:16 > 0:05:21No-one died in 2010, but as events unfolded,
0:05:21 > 0:05:27the Icelandic president had a stark warning for the rest of the world.
0:05:27 > 0:05:30Unfortunately, what we have seen in the last few days
0:05:30 > 0:05:33could only be a beginning of an experience
0:05:33 > 0:05:36which might be repeated throughout the 21st century
0:05:36 > 0:05:41because the scientific evidence points towards larger eruptions
0:05:41 > 0:05:42in the near future.
0:05:44 > 0:05:47So I think we should, all of us, throughout Europe and the world,
0:05:47 > 0:05:51start planning in a calm and rational way for that eventuality.
0:05:54 > 0:05:56If there are bigger eruptions to come,
0:05:56 > 0:05:59I want to know when they might arrive
0:05:59 > 0:06:01and what the consequences could be
0:06:01 > 0:06:04for both Iceland and Europe.
0:06:07 > 0:06:10So, from Eyjafjallajokull, I'm setting out to visit
0:06:10 > 0:06:14a few of Iceland's 15 other active volcanoes,
0:06:14 > 0:06:18some of which have produced big eruptions in the past,
0:06:18 > 0:06:22and others which threaten to erupt again in the near future.
0:06:27 > 0:06:30Since Iceland was settled just over 1,000 years ago,
0:06:30 > 0:06:34on average there's been a volcanic eruption every five years.
0:06:36 > 0:06:40And one of the biggest and most devastating of those eruptions
0:06:40 > 0:06:43has changed the landscape of one corner of Iceland for ever.
0:06:50 > 0:06:54I think this is the strangest,
0:06:54 > 0:06:58most otherworldly landscape...
0:06:59 > 0:07:01..I've ever seen.
0:07:01 > 0:07:07It's just great, chaotic lumps and piles of rock
0:07:07 > 0:07:11covered in this thick, khaki-grey moss.
0:07:13 > 0:07:15It's just weird.
0:07:16 > 0:07:19It's almost as if some giant
0:07:19 > 0:07:23crumbled up pieces of cake all over the plains,
0:07:23 > 0:07:25and they've gone mouldy.
0:07:29 > 0:07:35This lumpy plain was formed in 1783 by an enormous eruption
0:07:35 > 0:07:38from a volcanic fissure called Laki.
0:07:38 > 0:07:40At over 20 kilometres wide,
0:07:40 > 0:07:44it's part of the biggest single lava flow on the planet.
0:07:46 > 0:07:50'To hear how it all happened, I'm meeting Henrik Olufsen,'
0:07:50 > 0:07:52a guide here in southern Iceland.
0:07:55 > 0:07:58This lava has its origin from Laki,
0:07:58 > 0:08:02and the fissures opened and it took only four days
0:08:02 > 0:08:07for the lava to run down, about 34 kilometres down to the lowlands.
0:08:07 > 0:08:12So it's, erm... You can't imagine how powerful it was.
0:08:12 > 0:08:15And that was ongoing for eight months.
0:08:16 > 0:08:19This map shows how the eruption spread
0:08:19 > 0:08:21from a fissure in the hills
0:08:21 > 0:08:26and fed two enormous lakes of lava which expanded across the plain
0:08:26 > 0:08:30and began to close in on a small farming community.
0:08:35 > 0:08:38These pictures from Hawaii in 2011
0:08:38 > 0:08:41show a fissure eruption in full flow.
0:08:48 > 0:08:52The lava fountains that burst from this short fissure
0:08:52 > 0:08:54were up to 50 metres high.
0:08:57 > 0:09:00It gives some idea of what the eruption in Iceland
0:09:00 > 0:09:02must have looked like.
0:09:05 > 0:09:10Although in 1783, the fissure was 25 kilometres long
0:09:10 > 0:09:14and the fountains of lava were 500 metres high,
0:09:14 > 0:09:16as tall as skyscrapers.
0:09:17 > 0:09:21Lava from the fissure spread over a vast area
0:09:21 > 0:09:23as far as the eye can see.
0:09:29 > 0:09:31How do we know so much about this eruption
0:09:31 > 0:09:33and the effects that it had?
0:09:33 > 0:09:36There was a pastor here, in this area.
0:09:36 > 0:09:38His name was Jon Steingrimsson.
0:09:38 > 0:09:42And he wrote some description about this eruption.
0:09:42 > 0:09:46Both from the geological side and also from the human side.
0:09:48 > 0:09:52The pastor described the scene as the lava poured out
0:09:52 > 0:09:55and made its way towards his village on the coast.
0:09:59 > 0:10:03TRANSLATION: "My companions and I walked towards the fissure.
0:10:03 > 0:10:07"There, a flood of fire flowed with the speed of a great river,
0:10:07 > 0:10:09"swollen from meltwater on a spring day.
0:10:11 > 0:10:14"In the middle of this fiery river, great cliffs
0:10:14 > 0:10:16"and slabs of rock were swept along,
0:10:16 > 0:10:21"tumbling about like large whales swimming, red hot and glowing."
0:10:25 > 0:10:28As the lava flow advanced towards their homes,
0:10:28 > 0:10:31the pastor gathered his congregation
0:10:31 > 0:10:33and gave what has become a famous sermon,
0:10:33 > 0:10:36known in Iceland as the Fire Mass.
0:10:37 > 0:10:42He inspired the villagers to face up to their situation without fear.
0:10:47 > 0:10:49His church was near here.
0:10:49 > 0:10:53Was it in a village that was eventually engulfed in the lava?
0:10:53 > 0:10:58Actually, the lava stopped two kilometres from the church
0:10:58 > 0:11:01where he was holding this great speech called Fire Mass,
0:11:01 > 0:11:07where he was trying to urge people to carry on and believe in life.
0:11:07 > 0:11:11Presumably, for the people, terrified in the church,
0:11:11 > 0:11:14they must have looked at their pastor and thought, somehow,
0:11:14 > 0:11:17- he had a direct connection to God.- Yeah.
0:11:20 > 0:11:24But lava was only part of the problem.
0:11:24 > 0:11:28The eruption also produced huge amounts of sulphur dioxide
0:11:28 > 0:11:31and fluorine, which poisoned the water
0:11:31 > 0:11:35and contaminated food for people and animals alike.
0:11:38 > 0:11:42As crops failed and livestock began to die,
0:11:42 > 0:11:47famine swept across huge swathes of Iceland.
0:11:47 > 0:11:5225% of the population of Iceland died because of hunger,
0:11:52 > 0:11:57and most of the island was totally covered with ash.
0:11:57 > 0:11:59And there was also a mist.
0:11:59 > 0:12:04You know, they hardly had sunlight for many months.
0:12:06 > 0:12:12The events of 1783 are an important chapter in Icelandic history.
0:12:12 > 0:12:1710,000 people died during the Laki eruptions,
0:12:17 > 0:12:20and it's a story which is still taught in school here.
0:12:21 > 0:12:25The courage shown by the pastor, Jon Steingrimsson,
0:12:25 > 0:12:28has also come to symbolise the attitude of Icelanders
0:12:28 > 0:12:31to the volcanoes around them.
0:12:35 > 0:12:37Is it something that's still referred to today?
0:12:37 > 0:12:40- Is it still talked about today? - Absolutely.
0:12:40 > 0:12:45It was a huge catastrophe for Icelanders,
0:12:45 > 0:12:49and we have to have this knowledge about it
0:12:49 > 0:12:52so we can learn and, you know, carry on.
0:12:52 > 0:12:57You're living, kind of, in the shadow of danger all the time.
0:12:57 > 0:13:02As an Icelander, is that sense of potential impending doom
0:13:02 > 0:13:05always slightly at the back of your mind?
0:13:05 > 0:13:08No. To be honest, no.
0:13:08 > 0:13:13If you understand it, if you have... If you respect it,
0:13:13 > 0:13:14you should not be afraid.
0:13:14 > 0:13:19So it's quite important for us to know about those things,
0:13:19 > 0:13:23because they will happen again, I can tell you.
0:13:29 > 0:13:34In 2010, it was a cloud of volcanic ash that made its way to Europe.
0:13:36 > 0:13:40But in 1783, the continent was engulfed
0:13:40 > 0:13:43by a huge cloud of sulphur dioxide.
0:13:43 > 0:13:47If a similar eruption happened again today,
0:13:47 > 0:13:51that toxic gas could have devastating consequences,
0:13:51 > 0:13:56particularly in densely populated areas like London.
0:13:56 > 0:13:58People would start to really struggle to breathe,
0:13:58 > 0:14:00the air quality would deteriorate dramatically.
0:14:00 > 0:14:03We'd probably struggle to see St Paul's across the river here.
0:14:05 > 0:14:07And so I would say that the disaster potentially could be
0:14:07 > 0:14:11greater in the 21st century than it was in the 18th century,
0:14:11 > 0:14:13and in the 18th century they thought it was the end of the world,
0:14:13 > 0:14:17so you can see that people... It's going to be bad.
0:14:17 > 0:14:19In the summer months, hot weather and air pollution
0:14:19 > 0:14:24often combine to reduce air quality in modern cities across Europe.
0:14:24 > 0:14:25Add volcanic gases to the mix
0:14:25 > 0:14:30and the result is a thick fog laced with sulphuric acid.
0:14:30 > 0:14:35At that point, people with fragile health or breathing problems
0:14:35 > 0:14:36can really begin to suffer.
0:14:40 > 0:14:44Professor John Grattan has found evidence in historical records
0:14:44 > 0:14:48showing that the arrival of volcanic fog from Iceland
0:14:48 > 0:14:51had similar effects over large swathes of Europe
0:14:51 > 0:14:53in the 18th century.
0:14:55 > 0:14:57On the 23rd of June 1783,
0:14:57 > 0:15:01people across Western Europe woke up to a changed world.
0:15:01 > 0:15:03There are descriptions of people waking up
0:15:03 > 0:15:06and looking out their window at their gardens and seeing
0:15:06 > 0:15:08that their fruit had fallen to the ground,
0:15:08 > 0:15:09forests being stripped of their leaves,
0:15:09 > 0:15:12and there was an intense smell of sulphur in the air.
0:15:16 > 0:15:18And they say that in the morning and in the evening,
0:15:18 > 0:15:20as the sun rises and sets,
0:15:20 > 0:15:23it's blood-red, like a red-hot pewter plate.
0:15:23 > 0:15:26And somebody describes it as "like a red-hot salamander",
0:15:26 > 0:15:29and people are really, really worried by this.
0:15:29 > 0:15:33There are very clear descriptions of people struggling to breathe,
0:15:33 > 0:15:37of an uncomfortable pressure, palpitations of the heart,
0:15:37 > 0:15:40of "mysterious agues and fevers",
0:15:40 > 0:15:44of outbreaks of terrible diarrhoea, "the bloody flux".
0:15:49 > 0:15:52As the summer advances and the smell of sulphur gets more intense,
0:15:52 > 0:15:54people start to die.
0:15:54 > 0:15:58People start to die in ones and twos, then in great numbers.
0:16:01 > 0:16:04There are descriptions of so many farmhands dying in the fields
0:16:04 > 0:16:07that the farmers were afraid they wouldn't be able
0:16:07 > 0:16:09to get their harvest in in time before the summer ended.
0:16:15 > 0:16:17Within the parishes we've looked at in England,
0:16:17 > 0:16:19we're looking at about 30,000 extra deaths -
0:16:19 > 0:16:20a doubling of the death rate -
0:16:20 > 0:16:23and it certainly seems to be higher than that in France.
0:16:23 > 0:16:26The research so far suggests about 250,000,
0:16:26 > 0:16:30so we're getting up towards 300,000 that we can be certain of,
0:16:30 > 0:16:35and nothing like that's ever been seen before, or frankly, since.
0:16:39 > 0:16:42It's quite natural at this time to invoke God.
0:16:42 > 0:16:44There are sermons which tell people
0:16:44 > 0:16:47that we think this is the end of the world, boys and girls,
0:16:47 > 0:16:49and you'd better start to take note of your soul.
0:16:51 > 0:16:54This is Armageddon, and you'd better take note of it.
0:17:02 > 0:17:06This was one of the largest eruptions in Icelandic history,
0:17:06 > 0:17:09but the earth only sees events of this size
0:17:09 > 0:17:11every few hundred years.
0:17:13 > 0:17:16So it may be several generations before we have to face up
0:17:16 > 0:17:18to problems like this in Europe.
0:17:24 > 0:17:28The colossal volcanic scar from the Laki eruption
0:17:28 > 0:17:31now stands as a monument to the lives that were lost,
0:17:31 > 0:17:34and this is just one of many fissures
0:17:34 > 0:17:37which cut across this landscape.
0:17:39 > 0:17:42The fissures in Iceland are part of a network of rifts
0:17:42 > 0:17:44that cross the entire planet.
0:17:44 > 0:17:48These are the boundaries between the tectonic plates,
0:17:48 > 0:17:52and they're home to 80% of the world's volcanoes.
0:17:56 > 0:17:59Iceland straddles one of those plate boundaries,
0:17:59 > 0:18:02where for 50 million years, the North American
0:18:02 > 0:18:06and Eurasian plates have been moving in opposite directions.
0:18:12 > 0:18:15The results of this violent tug of war
0:18:15 > 0:18:17are clearly visible in the landscape.
0:18:22 > 0:18:24As the plates pull apart,
0:18:24 > 0:18:28magma rises from the Earth's mantle to fill the gap.
0:18:30 > 0:18:34Millions of years of eruptions have piled lava flow upon lava flow
0:18:34 > 0:18:37to create an entire country.
0:18:39 > 0:18:42So the rift that splits this island in two
0:18:42 > 0:18:46is the birthplace of Iceland itself.
0:18:48 > 0:18:51And in the future, Iceland will continue to grow,
0:18:51 > 0:18:55which makes it vital that scientists understand
0:18:55 > 0:18:57exactly how the process works.
0:19:00 > 0:19:03Here in the south-west of the country,
0:19:03 > 0:19:08a recently explored site represents a unique opportunity to study
0:19:08 > 0:19:13one of these volcanoes not just on the surface, but from the inside.
0:19:17 > 0:19:20I've come here with Bjorn Oddsson,
0:19:20 > 0:19:23a volcanologist who's keen to get a first look
0:19:23 > 0:19:25at this geological one-off.
0:19:33 > 0:19:35We're joining a team of mountaineers
0:19:35 > 0:19:39who are making final preparations for our extraordinary descent...
0:19:42 > 0:19:45..a real life Journey To The Centre Of The Earth.
0:19:48 > 0:19:50They've rigged up a mechanical lift
0:19:50 > 0:19:53which will lower us directly into what was once
0:19:53 > 0:19:56the fiery mouth of this volcanic vent.
0:19:58 > 0:20:02I for one am slightly apprehensive.
0:20:07 > 0:20:10- Now, you've never been down here either?- No, I've never been here.
0:20:10 > 0:20:14Are you a little bit nervous about this slightly Heath Robinson
0:20:14 > 0:20:18piece of kit that we're descending into the bowels of the earth in?
0:20:18 > 0:20:21- No, I think it will work. - I hope so!- I hope so too.
0:20:22 > 0:20:24'Crossing the gantry to the lift
0:20:24 > 0:20:27'feels a little bit like walking the plank,
0:20:27 > 0:20:31'and the gaping hole beneath is impossible to ignore,
0:20:31 > 0:20:33'but finally we're ready to descend.'
0:20:34 > 0:20:35SHE GASPS
0:20:35 > 0:20:37It will be not so bad!
0:20:37 > 0:20:38SHE LAUGHS
0:20:38 > 0:20:40That's my nerves as well.
0:20:47 > 0:20:51OK, we're getting into a very narrow bit here.
0:20:53 > 0:20:56'It's a strange feeling,
0:20:56 > 0:21:00'being slowly swallowed up by the mouth of a volcano.'
0:21:03 > 0:21:09- It's a very kind of organic-feeling space, this, isn't it?- Yes.
0:21:09 > 0:21:13It feels almost alive, the shapes of the rock.
0:21:13 > 0:21:17- It's just like it happened yesterday.- Yeah!
0:21:17 > 0:21:19And what's amazing, just looking at the walls is,
0:21:19 > 0:21:22you can kind of see the bits of magma
0:21:22 > 0:21:25left on the side of the chamber.
0:21:25 > 0:21:28When it was plastered on the wall, it was not fully solidified,
0:21:28 > 0:21:32so in time it re-melts and drops down, and freezes.
0:21:32 > 0:21:35So these sort of chocolate-like drips stuck to the walls,
0:21:35 > 0:21:37that's the magma, the remnants of the magma?
0:21:37 > 0:21:39Yes, that's the remnants.
0:21:39 > 0:21:42Gravity pulls it down and forms these candle-like forms.
0:21:42 > 0:21:43That's incredible.
0:21:58 > 0:22:04'As we descend further, the throat of the volcano begins to widen out.
0:22:04 > 0:22:07'We're lowered into a vast open chamber.'
0:22:23 > 0:22:27'From top to bottom, it's 150 metres -
0:22:27 > 0:22:29'taller than St Paul's Cathedral.
0:22:33 > 0:22:36'We're now deep inside the body of this volcano,
0:22:36 > 0:22:40'in a space that would once have flowed with liquid magma.'
0:22:45 > 0:22:50So, is this the only place in the world that you know of
0:22:50 > 0:22:54that you can descend down into a volcano?
0:22:54 > 0:22:56Yes, as I know.
0:22:56 > 0:22:59And this is very special,
0:22:59 > 0:23:05because all the magma has drained away from here to the surface.
0:23:05 > 0:23:07So in normal circumstances,
0:23:07 > 0:23:10this immense cavern that we're standing in now...
0:23:10 > 0:23:12- It would be full of magma. - It would be full of magma.
0:23:12 > 0:23:14Yes, or lava, afterwards.
0:23:17 > 0:23:19Tell you what's so extraordinary,
0:23:19 > 0:23:24that I really wasn't expecting, was the colour.
0:23:24 > 0:23:26It's just a riot of every colour you can think of.
0:23:26 > 0:23:28That's due to many reasons.
0:23:28 > 0:23:32Iceland and Icelandic mountains were built up with many lava layers
0:23:32 > 0:23:35in many events of volcanic eruption,
0:23:35 > 0:23:38and we see both ash and lava
0:23:38 > 0:23:41from different types of volcanic eruptions.
0:23:41 > 0:23:42So this is like an open book.
0:23:42 > 0:23:45You can read the story of this mountain.
0:23:50 > 0:23:52'In the damp air of the cave,
0:23:52 > 0:23:55'chemical reactions have changed the colour of the rocks
0:23:55 > 0:23:58'like the rust on a piece of iron.
0:23:59 > 0:24:01'But as well as a beautiful sight,
0:24:01 > 0:24:05'the colourful shapes in the walls have a greater significance.
0:24:05 > 0:24:08'Like tree rings, the lava layers record
0:24:08 > 0:24:10'the history of eruptions here,
0:24:10 > 0:24:13'as they piled up one on top of another.
0:24:17 > 0:24:19'And running vertically through the walls,
0:24:19 > 0:24:23'this band of black rock marks the feeding channel
0:24:23 > 0:24:26'that supplied magma from deep beneath our feet.'
0:24:28 > 0:24:32- What you see here is like a wall of fire.- Right.
0:24:32 > 0:24:36But this is just a wall of fire frozen underground.
0:24:36 > 0:24:38'It cuts across this cave,
0:24:38 > 0:24:41'and it runs along the entire length of the fissure
0:24:41 > 0:24:44'underneath the volcanic ridges on the surface,
0:24:44 > 0:24:48'which it created a few thousand years ago.'
0:24:49 > 0:24:53And we can see the direction of these lines
0:24:53 > 0:24:58is parallel to all the mountain ridges we see on the surface.
0:25:00 > 0:25:04Most volcanic eruptions in Iceland are on fissures,
0:25:04 > 0:25:07so Iceland is pulled apart,
0:25:07 > 0:25:11and on one side we see the North American plate,
0:25:11 > 0:25:13on the other side we see the Eurasian plate.
0:25:13 > 0:25:18So we're sort of standing in the middle of those two tectonic plates?
0:25:18 > 0:25:20Yes, of these two continents.
0:25:20 > 0:25:23Does that mean effectively what we're doing is standing
0:25:23 > 0:25:27in a kind of no man's land between the two?
0:25:27 > 0:25:28We are in Iceland!
0:25:28 > 0:25:30SHE LAUGHS
0:25:30 > 0:25:32Good answer.
0:25:35 > 0:25:41'This volcanic cathedral provides a fascinating new perspective
0:25:41 > 0:25:43'on Iceland's central rift,
0:25:43 > 0:25:47'and research here should help scientists like Bjorn
0:25:47 > 0:25:51'to understand better how the opening of that rift
0:25:51 > 0:25:55'controls Iceland's volcanic activity.
0:25:55 > 0:26:01'The last eruption on this part of the rift was 3,000 years ago,
0:26:01 > 0:26:05'but other parts of the rift have opened up much more recently,
0:26:05 > 0:26:07'as the inhabitants of an island
0:26:07 > 0:26:11'just off the south coast of Iceland can testify.'
0:26:23 > 0:26:25This is Heimaey,
0:26:25 > 0:26:30and the entrance to its harbour is protected by dark, looming cliffs -
0:26:30 > 0:26:35a clue to events which rocked this place to its foundations
0:26:35 > 0:26:36almost 40 years ago.
0:26:50 > 0:26:54Does this volcano come as a complete surprise to you,
0:26:54 > 0:26:56or did you have any warning?
0:26:56 > 0:27:00There was no warning whatsoever until 10 o'clock yesterday evening.
0:27:00 > 0:27:02- Which was the earthquake.- Yes.
0:27:07 > 0:27:10'Lava entering the sea causes the water to virtually boil,
0:27:10 > 0:27:14'and sends clouds of steam thousands of feet up into the air.'
0:27:33 > 0:27:37On the morning of January 23, 1973,
0:27:37 > 0:27:40a fissure a mile long opened up
0:27:40 > 0:27:43and split this part of the island in two.
0:27:43 > 0:27:48Great fiery fountains of lava lit up the night sky,
0:27:48 > 0:27:49alerting the people in this town
0:27:49 > 0:27:53that they had to escape, and quickly.
0:27:57 > 0:28:03Today on Heimaey, evidence of that volcanic eruption is easy to find.
0:28:05 > 0:28:09This was the stuff that was coming out of that fissure.
0:28:09 > 0:28:12It is actually a sort of ash, but it's more like gravel,
0:28:12 > 0:28:15and it was literally raining down.
0:28:17 > 0:28:20But of course, it wasn't cool, inert stuff like this -
0:28:20 > 0:28:24it was at about 1,000 degrees Celsius.
0:28:24 > 0:28:27And this wasn't all that was coming out of that fissure.
0:28:27 > 0:28:30There were enormous lumps of lava like this.
0:28:30 > 0:28:34This is called a lava bomb, and these were being thrown out.
0:28:35 > 0:28:40Great molten lumps of rock that came thudding into the ground.
0:28:40 > 0:28:43So to be here when that happened
0:28:43 > 0:28:46must have felt like being in a living hell.
0:28:49 > 0:28:51To the 5,000 inhabitants of this tiny island,
0:28:51 > 0:28:53it felt like the end.
0:28:55 > 0:28:58The volcano threatened to engulf everything,
0:28:58 > 0:29:00and although it was a heart-wrenching decision,
0:29:00 > 0:29:04they knew immediately that they had to leave.
0:29:08 > 0:29:11It was pure luck that the night the volcano erupted,
0:29:11 > 0:29:14the harbour was full of fishing boats, and on a normal night,
0:29:14 > 0:29:18all the men and all the boats would have been out at sea.
0:29:18 > 0:29:21But there'd been a huge storm the night before
0:29:21 > 0:29:27that had kept men and boats at home, so when the volcano erupted,
0:29:27 > 0:29:30suddenly there was a means of escape
0:29:30 > 0:29:34from what must have seemed at the time an inescapable fate.
0:29:38 > 0:29:42Most of the population was evacuated to the mainland by boat,
0:29:42 > 0:29:45but Heimaey's natural harbour makes it
0:29:45 > 0:29:49the most profitable fishing port in the whole of Iceland,
0:29:49 > 0:29:53and no-one was willing to abandon this place for good.
0:29:53 > 0:29:55Determined to preserve their way of life,
0:29:55 > 0:29:57about 100 men stayed behind
0:29:57 > 0:30:01to try and save as many homes as they could.
0:30:05 > 0:30:09At first, they concentrated on clearing ash,
0:30:09 > 0:30:11hoping to stop roofs collapsing.
0:30:14 > 0:30:19But the ash kept falling and many houses were soon completely buried.
0:30:22 > 0:30:25Where a whole neighbourhood once thrived,
0:30:25 > 0:30:29just a single chimney now emerges from the ash.
0:30:34 > 0:30:38After a month, the eruption showed no sign of abating.
0:30:38 > 0:30:42And a huge lava flow advanced towards the town,
0:30:42 > 0:30:45consuming everything in its path.
0:30:45 > 0:30:49And when the lava finally reached the coast,
0:30:49 > 0:30:53it began to threaten the most valuable part of the island.
0:30:54 > 0:30:59The harbour entrance in Heimaey was just a few hundred metres wide.
0:31:00 > 0:31:03But as lava added new land to the coast,
0:31:03 > 0:31:08there was a real chance that the gap might be closed forever.
0:31:09 > 0:31:14For those who had stayed behind, like local welder Halle Tryggvason,
0:31:14 > 0:31:18that was the moment the real fight back began.
0:31:18 > 0:31:21TRANSLATOR: We knew we had to save the harbour,
0:31:21 > 0:31:25because our livelihood depends on being able to sail out to sea.
0:31:25 > 0:31:29If we're going to live on this island, we have to be able to fish.
0:31:29 > 0:31:32Our town and way of life wouldn't last long without the fishing industry.
0:31:32 > 0:31:35That's just the way it is.
0:31:36 > 0:31:42It seemed impossible that anything could be done to save the harbour.
0:31:42 > 0:31:44But something that had happened ten years earlier
0:31:44 > 0:31:47provided a glimmer of hope.
0:31:51 > 0:31:53Just a few kilometres from Heimaey,
0:31:53 > 0:31:57an underwater volcano broke the surface in 1963
0:31:57 > 0:32:02to create a brand-new island called Surtsey.
0:32:04 > 0:32:06As lava flowed into the sea,
0:32:06 > 0:32:11one volcanologist had watched as it cooled and hardened on contact
0:32:11 > 0:32:16with the water, creating a barrier which diverted the flows behind it.
0:32:19 > 0:32:23Ten years later, he realised that what he'd witnessed
0:32:23 > 0:32:26could be the key to saving Heimaey's harbour
0:32:26 > 0:32:29and he proposed that they spray seawater
0:32:29 > 0:32:31directly onto the advancing lava.
0:32:33 > 0:32:37I was put to work welding pipes together.
0:32:37 > 0:32:41As soon as we began spraying cold seawater on the lava,
0:32:41 > 0:32:44it started hardening and gradually heaping up.
0:32:44 > 0:32:47We noticed that the lava was losing ground
0:32:47 > 0:32:51and actually being diverted, so everyone was saying, "It's working.
0:32:51 > 0:32:54"Spray more on it. Spray more."
0:32:57 > 0:33:00Halle and the rest of the team worked around the clock.
0:33:03 > 0:33:05A huge network of pipes was put together
0:33:05 > 0:33:10and extra pumps were shipped in to get water right into the heart
0:33:10 > 0:33:11of the lava flow.
0:33:19 > 0:33:24An unbelievable amount of sea water was sprayed onto the lava
0:33:24 > 0:33:26to try and stop its advance.
0:33:28 > 0:33:31Huge amounts. Constantly.
0:33:32 > 0:33:37I have no idea how much, but it would be fun to know.
0:33:40 > 0:33:43Incredibly, cooled by the water,
0:33:43 > 0:33:49a huge barrier of solidified lava was built up alongside the harbour.
0:33:49 > 0:33:54This new wall of rock stopped the lava flow 200 metres short
0:33:54 > 0:33:56of the cliffs on the far side.
0:33:59 > 0:34:05Today that gap remains, and access to the harbour has been preserved.
0:34:05 > 0:34:08By taking on the volcano,
0:34:08 > 0:34:12the people of Heimaey had maintained their livelihood.
0:34:12 > 0:34:17And to this day, they continue to harvest the rich fishing grounds
0:34:17 > 0:34:19of the northern Atlantic.
0:34:21 > 0:34:25It must have been a really fantastic feeling
0:34:25 > 0:34:30that somehow, against all odds, you were doing it.
0:34:30 > 0:34:36A volcano isn't exactly an ordinary kind of adversity. Not at all.
0:34:36 > 0:34:39So it was amazing to see our plan actually working.
0:34:39 > 0:34:41It's incredible that we were able to stop the lava
0:34:41 > 0:34:44and save our town, as well as our harbour.
0:34:44 > 0:34:47It was miraculous. It just worked.
0:34:50 > 0:34:53By standing up to the eruption, the people of Heimaey had shown
0:34:53 > 0:34:58a typically Icelandic resilience to the volcanoes around them.
0:34:58 > 0:35:00As Iceland's Prime Minister told me,
0:35:00 > 0:35:05the people of all of Iceland live with fire beneath their feet.
0:35:07 > 0:35:11It was a life-changing event for the population of this island.
0:35:12 > 0:35:16But as with the vast majority of Icelandic eruptions,
0:35:16 > 0:35:19only a small area was affected.
0:35:23 > 0:35:27When Eyjafjallajokull erupted in 2010,
0:35:27 > 0:35:31the effects extended way beyond southern Iceland.
0:35:32 > 0:35:36So what is it about this volcano that made it capable
0:35:36 > 0:35:38of causing an international incident?
0:35:41 > 0:35:45To find out, I'm heading to the summit,
0:35:45 > 0:35:49using specially adapted Jeeps to cross the glacial ice.
0:35:49 > 0:35:53Why is it necessary to have such big tyres?
0:35:53 > 0:35:56Is it just to make you feel a bit more macho?
0:35:56 > 0:36:00A little bit like that, yes. No! THEY LAUGH
0:36:06 > 0:36:12We climb 1,500 metres before arriving at the crater's edge.
0:36:13 > 0:36:15Again, I've joined Bjorn Oddsson
0:36:15 > 0:36:19who's part of the team that made a surprisingly discovery
0:36:19 > 0:36:22about the 2010 eruption.
0:36:25 > 0:36:29'We've come as close to the edge of Eyjafjallajokull's main crater
0:36:29 > 0:36:30'as we dare.
0:36:30 > 0:36:34'Beyond here, the walls of this new gash in the ice'
0:36:34 > 0:36:36are extremely unstable,
0:36:36 > 0:36:39tumbling down to the steaming vent below.
0:36:44 > 0:36:48So, we are standing here on the Eyjafjallajokull volcano
0:36:48 > 0:36:51and we're going to look into the crater with a thermal camera
0:36:51 > 0:36:55and see the heat it's still generating two years later.
0:36:55 > 0:37:01When the magma is erupted, it's close to 1,100 or 1,200 degrees in Celsius.
0:37:01 > 0:37:04- Wow.- And by the time it cools down
0:37:04 > 0:37:07and I would guess that just below the surface it's around boiling point.
0:37:07 > 0:37:11- Several metres down, you would find 600-800 degrees in Celsius.- Wow.
0:37:11 > 0:37:14Because it takes a really long time to cool down.
0:37:14 > 0:37:21Does that mean that the volcano is still sort of in eruption mode,
0:37:21 > 0:37:25- if you like? Could it still go any minute?- It still can go any minute.
0:37:25 > 0:37:28But it will probably be like this for many years
0:37:28 > 0:37:30and the core beneath will be warm.
0:37:30 > 0:37:35- Even though we're 1,500 metres up and it's freezing?- Yes. Even though.
0:37:35 > 0:37:38SHE LAUGHS Even though.
0:37:38 > 0:37:42I think the abiding memory that everybody has of this eruption
0:37:42 > 0:37:47were those vast, towering ash clouds that then got dispersed
0:37:47 > 0:37:50not just across Iceland, but all the way to northern Europe.
0:37:50 > 0:37:56Why ash? Why did this volcano generate so much ash?
0:37:56 > 0:37:59That's due to the volcanic happening under ice,
0:37:59 > 0:38:03so it produced a lot of meltwater and the interaction between lava
0:38:03 > 0:38:08and ice breaks up all the lava and forms ash,
0:38:08 > 0:38:12which is transported into ash plumes and dispersed in the atmosphere.
0:38:14 > 0:38:18Meltwater in the summit crater interacts with the lava
0:38:18 > 0:38:20emerging from the vent.
0:38:20 > 0:38:25The resulting steam explosions rip the magma into tiny fragments,
0:38:25 > 0:38:27better known as ash.
0:38:32 > 0:38:36If it would happen on dry land, then we would see lava flowing around.
0:38:36 > 0:38:41- Right.- But when we mix water and magma, it turns explosive.
0:38:41 > 0:38:45And all the product is ash but not lava.
0:38:46 > 0:38:51During the eruption, a quarter of a million cubic metres of ash
0:38:51 > 0:38:54was blasted high into the atmosphere.
0:38:59 > 0:39:02Long-lasting high pressure over the Atlantic
0:39:02 > 0:39:04created strong northerly winds,
0:39:04 > 0:39:08which carried the ash towards continental Europe.
0:39:09 > 0:39:11In many eruptions,
0:39:11 > 0:39:15the supply of magma runs out after a couple of days.
0:39:15 > 0:39:17But not here.
0:39:17 > 0:39:24In 2010, Eyjafjallajokull continued to pump out ash for over a month.
0:39:28 > 0:39:32What was it that made this eruption go on so long?
0:39:32 > 0:39:36Was it something particular about this volcano?
0:39:36 > 0:39:40Access of a huge amount of magma.
0:39:40 > 0:39:45It seems like the magma from the last eruption has been resting
0:39:45 > 0:39:48- under the volcano...- Wow. - ..since 1821.
0:39:48 > 0:39:51So, hang on a second. Let me see if I can understand this properly.
0:39:51 > 0:39:57- You're saying that the last eruption here was in 18...?- 1821.- 1821.
0:39:57 > 0:40:02And the magma came up, as we expect, up the sort of chimney,
0:40:02 > 0:40:07if you like, up to the crater, but some of it got sort of stuck
0:40:07 > 0:40:11on the way, went down a little channel or a little tunnel
0:40:11 > 0:40:13- and just sat there?- Yes.
0:40:13 > 0:40:20And then, 2010, you have another great boiling up of original magma,
0:40:20 > 0:40:22if you like, at the bottom of the chamber,
0:40:22 > 0:40:28that starts to travel up. The old magma wakes up and goes, "Hang on a second, what's going on?"
0:40:28 > 0:40:29- And that comes up with it?- Yes.
0:40:29 > 0:40:34- You scientists are quite clever, aren't you?- Yes. THEY LAUGH
0:40:37 > 0:40:42So when Eyjafjallajokull came to life once more in 2010,
0:40:42 > 0:40:47the old magma was stirred up and it too emerged from the crater,
0:40:47 > 0:40:48adding to the volume of ash
0:40:48 > 0:40:52and extending the eruption for much longer than expected.
0:40:58 > 0:41:02- Is this our picnic? - This is our picnic.
0:41:05 > 0:41:09So, during the eruption, all this area was covered by ash.
0:41:09 > 0:41:14- So this would've been black? - All black, several metres.- Right.
0:41:14 > 0:41:18But it's two years since, so we had two years of winter snow.
0:41:18 > 0:41:22So maybe 10, 15 metres of snow on top of it,
0:41:22 > 0:41:26- so we don't see any ash here right now. - 'The ash might all be buried now,
0:41:26 > 0:41:29'but Bjorn has brought a sample with him
0:41:29 > 0:41:32'to explain what it tells us about the eruption.'
0:41:32 > 0:41:39- This is the very ash that came out of this volcano in 2010?- Yes.
0:41:39 > 0:41:43- Wow.- And in the beginning, it was this fine-grained ash,
0:41:43 > 0:41:45so you can feel it in your fingers.
0:41:45 > 0:41:49- It's a little bit muddy.- Yeah.
0:41:49 > 0:41:53And this is the fine grain that gets highest in the atmosphere
0:41:53 > 0:41:55and is carried most way from the volcano.
0:41:55 > 0:42:00- So this would have been the stuff that caused all the disruption in Europe?- Yes.- Right.
0:42:00 > 0:42:04- And with time, it got more coarse grained, the eruption.- Right.
0:42:04 > 0:42:06So it changes with time.
0:42:06 > 0:42:11And this ash here we see is more like sand, it doesn't stick together.
0:42:11 > 0:42:12Oh, it is, it's completely different.
0:42:12 > 0:42:14- It's much grittier, isn't it?- Yes.
0:42:14 > 0:42:18This is affecting the local more than the finer ones.
0:42:18 > 0:42:22Right, because this would have been too heavy to have a blown all that way.
0:42:28 > 0:42:32Until 2010, this was considered a dormant volcano.
0:42:33 > 0:42:38And people had been living and working in its shadow for generations.
0:42:39 > 0:42:45Helga Haraldsdottir has a small farm beneath Eyjafjallajokull
0:42:45 > 0:42:49and I've come to see how she coped with the eruption here
0:42:49 > 0:42:50two years ago.
0:42:51 > 0:42:56So, can you tell me what happened on that morning
0:42:56 > 0:42:59when the eruption started? What did you hear and see?
0:42:59 > 0:43:05We just saw these big, big gushes of ash coming up
0:43:05 > 0:43:06and going east over the mountains.
0:43:06 > 0:43:09So it was at that point it was going away from you.
0:43:09 > 0:43:10Yes, it was going away.
0:43:10 > 0:43:13And we immediately started to prepare,
0:43:13 > 0:43:17trying to tighten all the houses, getting animals inside...
0:43:18 > 0:43:20..and prepare for it.
0:43:22 > 0:43:26Helga's photographs, taken when the eruption began,
0:43:26 > 0:43:30show westerly winds taking the ash away from her land.
0:43:30 > 0:43:32But after just two days,
0:43:32 > 0:43:38the winds swung around to bring the ash cloud straight towards her farm.
0:43:43 > 0:43:48This big dark, brownish cloud
0:43:48 > 0:43:51getting probably three, four kilometres higher
0:43:51 > 0:43:54and just coming crawling down here over the hills.
0:43:54 > 0:43:59- So it was sweeping down across here? - Sweeping down from the glacier.
0:43:59 > 0:44:03And in the end, we just disappeared into it.
0:44:03 > 0:44:06Everything was pitch black and we didn't see anything.
0:44:14 > 0:44:17Even though you understood what it was,
0:44:17 > 0:44:20it must still have been quite frightening.
0:44:20 > 0:44:24- Yes, it was. You really don't know what to expect.- Yeah.
0:44:24 > 0:44:27You never know how you're going to react to it, really.
0:44:28 > 0:44:33It was just like Christmas snowing, except it was black.
0:44:34 > 0:44:38It was not that heavy, but it was like a fine, fine sand,
0:44:38 > 0:44:40got into your eyes, into your mouth.
0:44:41 > 0:44:45I mean, it sounds perhaps a rude question,
0:44:45 > 0:44:51but did you not think that buying a farm right underneath a volcano
0:44:51 > 0:44:53was possibly unwise?
0:44:53 > 0:44:55- No, I don't think so. - KATE CHUCKLES
0:44:55 > 0:45:01I don't think anybody considered Eyjafjallajokull was an active volcano.
0:45:01 > 0:45:04- Really?- It hadn't erupted for 200 years
0:45:04 > 0:45:06and we didn't really think it would go off.
0:45:06 > 0:45:08THEY LAUGH
0:45:09 > 0:45:13Wasn't your first reaction just to run away? I mean, what did you do?
0:45:13 > 0:45:16No, my first reaction was, "Get all the horses inside!"
0:45:16 > 0:45:20We were getting everything inside and, well, it was that close
0:45:20 > 0:45:24we were putting the last horse ass inside the door
0:45:24 > 0:45:26when heaven falls upon us.
0:45:28 > 0:45:32- Was it covered in ash?- It was absolutely pitch black, everything.
0:45:32 > 0:45:35It was from five centimetres thick and then,
0:45:35 > 0:45:39as it went closer to the volcano, it just got thicker and thicker.
0:45:43 > 0:45:47Helga and her family, along with the other local farmers,
0:45:47 > 0:45:48were evacuated.
0:45:52 > 0:45:56They could only visit once a day to feed their animals
0:45:56 > 0:45:59and had to wear masks to keep out the ash.
0:46:00 > 0:46:05The eruption had come at the worst possible moment,
0:46:05 > 0:46:08because April here is the start of the lambing season.
0:46:08 > 0:46:13It's a part of the year that can be stressful at the best of times.
0:46:13 > 0:46:17But for Helga, in 2010 it was a nightmare.
0:46:17 > 0:46:20Even with the animals inside,
0:46:20 > 0:46:24the thick ash cloud still crept in through windows and doors.
0:46:28 > 0:46:33Did you notice any adverse health effects from this ash on you
0:46:33 > 0:46:35or indeed your animals?
0:46:35 > 0:46:38I couldn't see any on the adult animals,
0:46:38 > 0:46:41but we lost the first six or seven lambs.
0:46:41 > 0:46:45- Wow.- So I think it was just the amount of ash in the air,
0:46:45 > 0:46:47it was too much for them.
0:46:47 > 0:46:51I always slaughter some lambs in the autumn,
0:46:51 > 0:46:55and I noticed they had black spots in the lungs.
0:46:55 > 0:46:57Some tiny, tiny and others large.
0:46:57 > 0:47:00Then I killed one, a two-year-old
0:47:00 > 0:47:06and she had brownish stripes in her lungs as big, thick as my finger.
0:47:06 > 0:47:08- Wow.- Just going through the lungs.
0:47:08 > 0:47:13Are you worried that given the state of your sheeps' lungs,
0:47:13 > 0:47:16that your lungs might not be so great either?
0:47:16 > 0:47:20- Yeah, I think I got some ash down there but...- You're coping.
0:47:20 > 0:47:25Yeah, I can then use it as an excuse when I can't run any more!
0:47:30 > 0:47:35So, once this ash cloud had passed,
0:47:35 > 0:47:38what were you left with? What did the farm look like?
0:47:38 > 0:47:43Well, everything was kind of in greyish, dark colours.
0:47:43 > 0:47:48We had about five to seven centimetres thick ash over everything.
0:47:48 > 0:47:54Then when it rained, it got into this disgusting mud
0:47:54 > 0:47:58and then when it dried up again, it was just like a concrete
0:47:58 > 0:48:01over everything.
0:48:01 > 0:48:04- What did you think you could do? - Nothing. You couldn't do anything.
0:48:04 > 0:48:08You just had to wait and see what will happen.
0:48:08 > 0:48:11And we took the point early on that we're just going to try
0:48:11 > 0:48:14to stick with it, see how it goes.
0:48:14 > 0:48:16But we were not going to throw in the towel yet.
0:48:16 > 0:48:20So what happened to all the ash? Did you literally have to scrape it up?
0:48:20 > 0:48:24- No, no, no. It's just sitting under the grass.- Yeah.
0:48:28 > 0:48:31Looking at the area around the farm now,
0:48:31 > 0:48:36it's hard to believe it was once blanketed by thick, black ash.
0:48:38 > 0:48:42- God, it is beautiful here. - Yes, it is.
0:48:42 > 0:48:46- Oh, look at your lambs. - HELGA CALLS IN NATIVE TONGUE
0:48:46 > 0:48:49'This year's lambing season has just begun
0:48:49 > 0:48:53'and life on Helga's farm has returned to normal.'
0:48:53 > 0:48:56- Have these just been born? They look very young.- Yes.
0:48:57 > 0:48:59They are adorable!
0:49:00 > 0:49:05- Have you ever thought, "Actually, I just want to move"?- No. No.
0:49:05 > 0:49:07It's the best spot in Iceland.
0:49:07 > 0:49:08- Really?- Yes.
0:49:08 > 0:49:12It's way, way colder just ten kilometres to the east or west
0:49:12 > 0:49:16over the winter, so it's the best spot in Iceland.
0:49:16 > 0:49:21And if Eyjafjallajokull was to decide to erupt again next year,
0:49:21 > 0:49:23- would you still feel the same? - Yes, I think so.
0:49:23 > 0:49:28I would just be a little bit more prepared what to do!
0:49:32 > 0:49:36The people of Iceland have had to live with volcanic eruptions
0:49:36 > 0:49:40since the country was settled in the ninth century.
0:49:40 > 0:49:43Since then, there's been a pattern,
0:49:43 > 0:49:48a peak in the level of activity, which comes every 140 years.
0:49:50 > 0:49:55Scientists believe that the next peak could come as soon as 2030.
0:49:56 > 0:49:59But events over the last couple of years
0:49:59 > 0:50:02suggest that things might have already begun to pick up.
0:50:03 > 0:50:08In March, 2010, there was a spectacular lava eruption
0:50:08 > 0:50:11just a few kilometres from Eyjafjallajokull.
0:50:14 > 0:50:16In May, 2011,
0:50:16 > 0:50:21another explosive eruption happened at a volcano called Grimsvotn.
0:50:23 > 0:50:28And later the same year, there was a burst of geothermal activity
0:50:28 > 0:50:32beneath the glacier at Katla, one of Iceland's biggest volcanoes.
0:50:35 > 0:50:39Now that geothermal activity heated up the ice
0:50:39 > 0:50:44and caused a flood of water to come pouring off the volcano
0:50:44 > 0:50:47and down this river valley, taking out the bridge
0:50:47 > 0:50:51and causing mass devastation as it made its way to the sea.
0:50:56 > 0:51:00Katla is just 20 kilometres from Eyjafjallajokull,
0:51:00 > 0:51:02but it's much, much bigger.
0:51:02 > 0:51:04And in Iceland,
0:51:04 > 0:51:07many people are worried that an eruption here could be next.
0:51:11 > 0:51:15The time for Katla to erupt is coming close.
0:51:15 > 0:51:17I don't say "if", but I say "when".
0:51:17 > 0:51:20So I think it is high time for European governments
0:51:20 > 0:51:23and airline authorities all over Europe and the world
0:51:23 > 0:51:27to start planning for the eventual Katla eruption.
0:51:27 > 0:51:30I'm heading for the summit of Katla
0:51:30 > 0:51:34to see how scientists are using the latest technology
0:51:34 > 0:51:37to keep a close eye on this volcanic giant.
0:51:40 > 0:51:45Crossing the vast summit icecap, we're joined by Dr Benni Ofeigsson,
0:51:45 > 0:51:49the man in charge of monitoring efforts here on Katla.
0:51:53 > 0:51:58He leads us to a rocky outcrop rising out of the icy plain,
0:51:58 > 0:52:01the highest point for miles around.
0:52:08 > 0:52:12- We are actually at the edge of the caldera rim.- Right.
0:52:12 > 0:52:16The caldera is a depression that is formed
0:52:16 > 0:52:18when a magma chamber is emptied.
0:52:18 > 0:52:22So what we're looking at here is snow and ice covering
0:52:22 > 0:52:25that kind of classic volcano crater,
0:52:25 > 0:52:28and the caldera stretches in which direction?
0:52:28 > 0:52:30If you look...
0:52:30 > 0:52:34look around here, we see the edge of the caldera rim.
0:52:34 > 0:52:36- So all the high points. - The high points here
0:52:36 > 0:52:41are at the edge of the caldera rim. All the way around.
0:52:41 > 0:52:44- I mean, it's absolutely enormous. - It's enormous.
0:52:44 > 0:52:46It's about ten kilometres diameter.
0:52:46 > 0:52:51- And how thick is the ice on top of it?- About 750 metres.- Wow.
0:52:53 > 0:52:57Calderas mark the top of the very biggest volcanoes in the world.
0:53:00 > 0:53:04And they're formed by what are known as super eruptions.
0:53:07 > 0:53:12The explosions that created Katla's caldera several hundred years ago
0:53:12 > 0:53:18were 50 times bigger than Eyjafjallajokull in 2010,
0:53:18 > 0:53:22depositing ash layers in Russia some 2,000 miles away.
0:53:26 > 0:53:31Fortunately, not every eruption here is quite that big.
0:53:31 > 0:53:34But Katla has seen plenty of activity
0:53:34 > 0:53:36in the last few hundred years.
0:53:39 > 0:53:42So, how active is this volcano?
0:53:42 > 0:53:48- Well, it has been erupting roughly once or twice every century.- OK.
0:53:48 > 0:53:54- So the last time it had a great eruption?- It was in 1918.
0:53:54 > 0:53:57It was about three times bigger than the Eyjafjallajokull eruption.
0:53:59 > 0:54:04In 1918, there was a huge ash eruption at Katla,
0:54:04 > 0:54:08which also unleashed a torrent of meltwater many times larger
0:54:08 > 0:54:10than the flood last year.
0:54:10 > 0:54:13It ripped huge chunks from the glacier
0:54:13 > 0:54:16and carried them like icebergs towards the coast.
0:54:18 > 0:54:20- That is almost a century ago.- Yes.
0:54:20 > 0:54:25- So does that mean it's kind of overdue?- Well, I wouldn't say that.
0:54:25 > 0:54:28Volcanoes aren't overdue, they change patterns
0:54:28 > 0:54:32on a regular basis or an irregular basis, actually.
0:54:32 > 0:54:34They are irregular and complex things.
0:54:34 > 0:54:38It might erupt in 10 years, it might erupt in 50 years.
0:54:38 > 0:54:40It might erupt in a few weeks.
0:54:40 > 0:54:41KATE CHUCKLES NERVOUSLY
0:54:41 > 0:54:44OK. Shall we get this job done, then?
0:54:48 > 0:54:52The length of time between eruptions at Katla varies a lot,
0:54:52 > 0:54:56'so the only way to anticipate the next episode of activity
0:54:56 > 0:55:00'is by carefully monitoring its behaviour.
0:55:00 > 0:55:05'Bolted to the rock, these GPS instruments use satellite technology
0:55:05 > 0:55:10'to accurately report their position every second of the day.
0:55:10 > 0:55:14'They show that the surface of this enormous volcano
0:55:14 > 0:55:16'is almost constantly on the move.'
0:55:16 > 0:55:22- It looks to the uninitiated eye that it's moving quite a lot.- Yes, it is.
0:55:22 > 0:55:24It is moving quite a lot.
0:55:24 > 0:55:28What we are looking at now is volcanic unrest
0:55:28 > 0:55:30and that's a long-term indicator
0:55:30 > 0:55:34that something is... could potentially happen.
0:55:34 > 0:55:38And it could potentially happen at short notice.
0:55:39 > 0:55:43'This shifting of the ground is often seen at active volcanoes,
0:55:43 > 0:55:47'but it doesn't necessarily mean an eruption is on the way.
0:55:47 > 0:55:51'What Benni is really looking out for is evidence that shows
0:55:51 > 0:55:55'whether the pressure is building in Katla's magma chamber
0:55:55 > 0:55:57'deep beneath our feet.'
0:55:59 > 0:56:05How does magma accumulating - kilometres below us, presumably -
0:56:05 > 0:56:10how does that affect a GPS instrument
0:56:10 > 0:56:13right up here on the surface?
0:56:13 > 0:56:16You have a magma chamber below a volcano
0:56:16 > 0:56:20and there is magma coming into that magma chamber.
0:56:20 > 0:56:24It increases the pressure in the magma chamber, so you're basically...
0:56:26 > 0:56:30- ..increasing it in size. - Right. So you...
0:56:30 > 0:56:33It's like blowing up a balloon, so you see it on a surface,
0:56:33 > 0:56:37- you see an uplift and away.- Ah.
0:56:37 > 0:56:42So Benni won't issue any warnings until he sees clear movement
0:56:42 > 0:56:47up and away from the magma chamber over a period of days or weeks.
0:56:47 > 0:56:50Only that would suggest that Katla is building up
0:56:50 > 0:56:52to a really big eruption.
0:56:58 > 0:57:02When Katla does erupt again,
0:57:02 > 0:57:04the consequences could be a lot more serious
0:57:04 > 0:57:08than the ash cloud that reached us two years ago.
0:57:08 > 0:57:12In Iceland, the population is well aware of that threat
0:57:12 > 0:57:16and of the dangers posed by all the other volcanoes around them.
0:57:22 > 0:57:24I've now met...
0:57:24 > 0:57:27a whole series of locals,
0:57:27 > 0:57:32scientists that are involved in how eruptions work
0:57:32 > 0:57:34and monitoring the volcanoes,
0:57:34 > 0:57:38and then just the regular people who live alongside them
0:57:38 > 0:57:40and with the consequences of them.
0:57:40 > 0:57:43And there's a sense of acceptance,
0:57:43 > 0:57:46but not resignation. It's very different.
0:57:46 > 0:57:48Um...
0:57:48 > 0:57:51And a sense of...
0:57:51 > 0:57:55This is just who we are and where we are.
0:57:55 > 0:57:59And it's very much part of us.
0:58:01 > 0:58:04There's a lot we can take from the Icelandic attitude
0:58:04 > 0:58:07to the volcanoes in their midst.
0:58:08 > 0:58:12We can't stop volcanic eruptions happening,
0:58:12 > 0:58:13but we can learn from them.
0:58:13 > 0:58:17And it's a lesson we should take seriously.
0:58:17 > 0:58:22Because there is no doubt that Iceland's volcanoes will erupt again.
0:58:23 > 0:58:25It's just a matter of when.
0:58:39 > 0:58:42Subtitles by Red Bee Media Ltd