0:00:02 > 0:00:04'I'm standing on the rim
0:00:04 > 0:00:07'of one of the most active volcanoes on the planet.
0:00:08 > 0:00:12'It's so powerful, it once blew the top off this entire island.'
0:00:14 > 0:00:19This is Marum, with its truly breathtaking lava lake.
0:00:19 > 0:00:22But to understand how this volcano is behaving,
0:00:22 > 0:00:25we need to get off the rim of this crater
0:00:25 > 0:00:29and descend towards that fiery inferno.
0:00:32 > 0:00:36'I've travelled over 10,000 miles to join a team of scientists
0:00:36 > 0:00:40'as they attempt to get under the skin of this volcano.'
0:00:41 > 0:00:43I can feel the heat now.
0:00:43 > 0:00:45'It's a challenge fraught with risk.'
0:00:45 > 0:00:47Ooo! Sorry! Oh, Tim, sorry!
0:00:47 > 0:00:48It's OK, no problem.
0:00:48 > 0:00:52'But it could give us an insight into its inner workings
0:00:52 > 0:00:54'never achieved before.'
0:00:54 > 0:00:58That's enough to kill you pretty quickly, actually.
0:00:58 > 0:01:03It can pump out more sulphur dioxide than anywhere else on earth
0:01:03 > 0:01:07in a toxic plume of gas that engulfs the island and its people.
0:01:10 > 0:01:14So I'll also be finding out how it affects the lives of the islanders.
0:01:15 > 0:01:16LAUGHTER
0:01:16 > 0:01:19What's so funny exactly?
0:01:20 > 0:01:24Is this volcano building towards another major eruption?
0:01:26 > 0:01:29- Oh, my God, it's really warm! Argh! - Whoa!
0:01:54 > 0:01:59I'm flying above the island of Ambrym in the Vanuatu archipelago.
0:01:59 > 0:02:02This island is home to one of the most dynamic
0:02:02 > 0:02:05and exciting volcanoes in the world.
0:02:05 > 0:02:06It's called Marum.
0:02:06 > 0:02:10And we're here to try and understand how this volcano works.
0:02:10 > 0:02:12What its personality is.
0:02:14 > 0:02:17Ambrym is one of the islands in the Vanuatu chain
0:02:17 > 0:02:21that sits on the edge of the Pacific Ring of Fire.
0:02:23 > 0:02:28Its volcano contains one of just five lava lakes in the world.
0:02:28 > 0:02:33A permanently-bubbling cauldron of molten rock that makes it unique.
0:02:38 > 0:02:40I've joined Professor Shane Cronin,
0:02:40 > 0:02:43who has been monitoring this volcano for a decade.
0:02:43 > 0:02:45I'd say it's dark and brooding.
0:02:45 > 0:02:49You've got this black ash, the lava, the shapes.
0:02:49 > 0:02:53He's here to find out if its behaviour is shifting.
0:02:55 > 0:02:58It brings me back time and time again to understand its moods,
0:02:58 > 0:03:00its changes, its effects on people.
0:03:00 > 0:03:05And what makes this volcano particularly unusual and special?
0:03:05 > 0:03:08One of the things about it that's so unusual is it's always erupting.
0:03:08 > 0:03:11It's not always throwing material in the air,
0:03:11 > 0:03:12but it's almost always erupting.
0:03:12 > 0:03:14There's almost always something going on.
0:03:14 > 0:03:18Magma is always there. It's alive, it's pulsing.
0:03:18 > 0:03:21And to understand the breadth of those changes,
0:03:21 > 0:03:23we do need to get a feel for that personality.
0:03:23 > 0:03:26When its moods shift, what might indicate a mood shift
0:03:26 > 0:03:30and what might indicate a hazard for the people living on the island.
0:03:34 > 0:03:37'This whole island is a volcano.
0:03:37 > 0:03:41'Its landscape scarred by the string of violent eruptions
0:03:41 > 0:03:45'which have frequently forced entire villages to be evacuated.
0:03:47 > 0:03:49'So, what's it like for the 7,000 people
0:03:49 > 0:03:53'who live their lives on the slopes of an active volcano?'
0:04:00 > 0:04:02Hi.
0:04:02 > 0:04:05- I'm Kate. - Hello, Kate. Welcome to Ambrym.
0:04:05 > 0:04:07Thank you. Oh, how beautiful!
0:04:07 > 0:04:10- They smell lovely. Thank you so much!- It's a pleasure.
0:04:10 > 0:04:12Look at this fantastic village!
0:04:15 > 0:04:19'As soon as we arrive, we're greeted Vanuatu-style.'
0:04:21 > 0:04:25Is this a normal occurrence when you come to an island like this?
0:04:25 > 0:04:27Well, on an island like this, when a plane comes,
0:04:27 > 0:04:31or when a cargo boat comes in, you know, it's a big occasion.
0:04:31 > 0:04:34- They look cute, don't they? - They do. They look amazing.
0:04:34 > 0:04:36TRIBAL SINGING
0:04:37 > 0:04:40- Hello!- Say hello.- CHILDREN: Hello!
0:04:40 > 0:04:42How are you? Hello?
0:04:42 > 0:04:43LAUGHTER
0:04:43 > 0:04:46What's so funny exactly? Hm?
0:04:46 > 0:04:48LAUGHTER
0:04:48 > 0:04:52It's very, very strange just dropping into a community like this.
0:04:52 > 0:04:56You come in across this thick, dense vegetation
0:04:56 > 0:04:59covering this incredibly rugged landscape.
0:04:59 > 0:05:01And that's all because of the volcano
0:05:01 > 0:05:03that totally dominates this island.
0:05:03 > 0:05:06But then you get to a place like this
0:05:06 > 0:05:08and it feels so benign and friendly
0:05:08 > 0:05:10and you can't believe that just up there
0:05:10 > 0:05:13is a great boiling pit of lava.
0:05:13 > 0:05:16And the impact on these villages will be enormous.
0:05:17 > 0:05:19- It's like Christmas.- Yeah.
0:05:19 > 0:05:20LAUGHTER
0:05:20 > 0:05:22Wow! Santa's sack!
0:05:22 > 0:05:27'Ambrym is so remote that planning a trip to the heart of its volcano
0:05:27 > 0:05:29'is a bit like a military operation.
0:05:29 > 0:05:32'Everything we need has to be flown in and carried with us
0:05:32 > 0:05:36'on the eight-hour hike to the summit in a few days' time.'
0:05:38 > 0:05:40You like to pack light.
0:05:40 > 0:05:42Yeah, I know. You volcanologists!
0:05:42 > 0:05:44I thought you just needed one little hammer.
0:05:45 > 0:05:49'I'm joining Shane and geologist Chris Firth...'
0:05:49 > 0:05:52- You got everything? - Yeah. It looks like it.
0:05:52 > 0:05:53I don't recognise any...
0:05:53 > 0:05:56'..as they attempt something they've never tried before.'
0:05:56 > 0:05:59I've got somebody else's bags entirely!
0:05:59 > 0:06:02'Abseiling right into this volcano
0:06:02 > 0:06:06'to find out if it's becoming more threatening.
0:06:06 > 0:06:09'But before we embark on our arduous journey to the top,
0:06:09 > 0:06:13'we'll be spending a few days in the village of Ranvetlam
0:06:13 > 0:06:15'so we can gather some crucial evidence
0:06:15 > 0:06:18'about the forces at work deep below us.'
0:06:19 > 0:06:20So this is where you'll be staying.
0:06:20 > 0:06:22It's beautiful.
0:06:22 > 0:06:27'Here, like everywhere on Vanuatu, pigs are part of village life.'
0:06:27 > 0:06:28I love pigs.
0:06:28 > 0:06:30LAUGHTER
0:06:31 > 0:06:34- They roam around the village. - They do?- Yes.
0:06:34 > 0:06:35Just completely free?
0:06:35 > 0:06:37Yeah. But they belong to someone.
0:06:37 > 0:06:41- OK. So you're saying, don't steal one.- No.- No.
0:06:41 > 0:06:43LAUGHTER
0:06:48 > 0:06:51The threat of an eruption is ever-present on Ambrym,
0:06:51 > 0:06:54so Chris and Shane want to gauge the level of risk
0:06:54 > 0:06:57Marum poses to the people living here.
0:06:59 > 0:07:02Volcanoes are highly volatile and unpredictable,
0:07:02 > 0:07:06but Shane helped devise a scale of risk for Ambrym's volcano
0:07:06 > 0:07:09that's internationally recognised.
0:07:11 > 0:07:16We're here to find out if Marum's hazard level needs to be increased
0:07:16 > 0:07:19and the islanders warned of any imminent danger.
0:07:27 > 0:07:29CHILDREN SING
0:07:39 > 0:07:43So, Shane, can you give me a sort of geological lie of the land?
0:07:43 > 0:07:47So we are located right up here, by Ranvetlam at the moment.
0:07:47 > 0:07:50So we're in that northern Ambrym and Marum is here.
0:07:50 > 0:07:51And we are north of the caldera.
0:07:51 > 0:07:55So the central part of the island, this caldera system
0:07:55 > 0:07:58is where the bulk of the magma is right here.
0:07:58 > 0:08:02This volcano, if not unique, certainly unusual
0:08:02 > 0:08:05is the fact that it has this open lava lake, doesn't it?
0:08:05 > 0:08:07- Yeah.- And not even one, but more than one.
0:08:07 > 0:08:09- Right.- Which is certainly unique amongst volcanoes.
0:08:09 > 0:08:12This volcano is more or less in a constant state of eruption.
0:08:12 > 0:08:15So when you look at the eruptive history of it
0:08:15 > 0:08:20and see a lava lake here, lava lake there, it comes and goes,
0:08:20 > 0:08:23the whole thing is always in a state of flux.
0:08:23 > 0:08:26Do you know yet whether it could then go into
0:08:26 > 0:08:31a more violent, eruptive stage than simply being a lava lake?
0:08:31 > 0:08:34The best example we have of that is about 2005.
0:08:34 > 0:08:37In 2005, this was the biggest point source
0:08:37 > 0:08:40- of sulphur dioxide on the planet. - Wow!
0:08:40 > 0:08:42So that's the sort of thing we will be looking for
0:08:42 > 0:08:46in terms of trying to understand the state of the volcano
0:08:46 > 0:08:48is how much gas is coming out of it,
0:08:48 > 0:08:52how vigorous, or how active the lava lake happens to be
0:08:52 > 0:08:57and what other features and signs we see of different types of activity.
0:08:59 > 0:09:02'In a couple of days, I'll be coming face to face with Marum,
0:09:02 > 0:09:05'and I'm already feeling anxious.'
0:09:18 > 0:09:20We've sent a team ahead to the summit.
0:09:20 > 0:09:23They're battling the elements and setting up camp.
0:09:25 > 0:09:28Sound of a good bolt is if it's singing to you.
0:09:28 > 0:09:30Hear that ding-ding?
0:09:30 > 0:09:31Beautiful.
0:09:31 > 0:09:35A team of six specialists is making the crucial preparations
0:09:35 > 0:09:37for us to abseil into the volcano
0:09:37 > 0:09:42so we can collect the evidence we need to find out if it's changing.
0:09:44 > 0:09:47The weather up there is highly unpredictable.
0:09:47 > 0:09:51And until they've finished building base camp, we can't join them.
0:09:51 > 0:09:54So for the next few days, I'll be finding out
0:09:54 > 0:09:56more about the island and its volcano
0:09:56 > 0:09:58to help us when we get there.
0:10:03 > 0:10:05Of all the Vanuatu islands,
0:10:05 > 0:10:09Ambrym is the most notorious for black magic.
0:10:09 > 0:10:14Marum is believed to hold the spirits of the islanders' ancestors.
0:10:14 > 0:10:16And the complex systems of belief here
0:10:16 > 0:10:20are deeply connected to the power of the volcano.
0:10:20 > 0:10:23So here, Kate, look, they are just weaving coconut leaves together
0:10:23 > 0:10:25- to go on top of the housing.- Ah!
0:10:25 > 0:10:28And I love the fact they, um...
0:10:29 > 0:10:31'I've asked anthropologist Haidy Geismar,
0:10:31 > 0:10:33'who has worked here over many years,
0:10:33 > 0:10:38'to help us understand how the volcano shapes what people believe.'
0:10:39 > 0:10:42The volcano is an intrinsic part of the environment.
0:10:42 > 0:10:46It affects the crops, it affects the soil, the fertility of the soil
0:10:46 > 0:10:49and the very ways in which people live.
0:10:49 > 0:10:51Are there lots of stories, are there lots of legends,
0:10:51 > 0:10:56I don't know, songs, carvings, that reflect the volcano, or not so much?
0:10:56 > 0:11:01Knowledge in Vanuatu is very placed in particular locations.
0:11:01 > 0:11:03And stories don't float around,
0:11:03 > 0:11:06they belong to places and people from particular places.
0:11:09 > 0:11:13We've heard one story which talks of a mysterious cave on the coast.
0:11:13 > 0:11:16A place believed to have the power to kill.
0:11:16 > 0:11:21We want to know if this power might be linked to the volcano.
0:11:23 > 0:11:25- Morning.- Morning.
0:11:25 > 0:11:28- Chief Harry, Kate.- Hello.
0:11:28 > 0:11:34- Shane. This is Chief Harry. He's the chief of Ranvetlam.- Oh, OK.
0:11:34 > 0:11:39'Chief Harry has local knowledge that might be of help to us.'
0:11:42 > 0:11:44You know when you want something where...
0:11:47 > 0:11:51Only find them in the 18th, 19th century.
0:11:51 > 0:11:54So this cave which is down by the sea,
0:11:54 > 0:11:57they discovered it in the 18th, 19th century.
0:11:57 > 0:12:01They saw that every time anything went inside, it died.
0:12:01 > 0:12:03So it's a place that people have known about
0:12:03 > 0:12:05these powers for quite some time
0:12:05 > 0:12:09and sometimes in the past, they have used them malevolently.
0:12:09 > 0:12:13If you take someone's leftover food and put it inside the cave,
0:12:13 > 0:12:15- then that person would die.- Wow!
0:12:15 > 0:12:16HE SPEAKS IN LOCAL DIALECT
0:12:18 > 0:12:22So Menuhin is a language word which means breathing.
0:12:22 > 0:12:25It means you become short of breath.
0:12:25 > 0:12:27- It pulls away your breath.- OK.
0:12:27 > 0:12:29If people are short of breath,
0:12:29 > 0:12:33- it sounds like carbon dioxide. - Right.
0:12:33 > 0:12:37I mean, a lot of people are killed by carbon dioxide in volcanic areas.
0:12:37 > 0:12:38- Yeah.- It's a silent killer.
0:12:40 > 0:12:43'Traditional beliefs in this village go hand in hand
0:12:43 > 0:12:48'with a desire to better understand the volcano using science.
0:12:49 > 0:12:51'And even though the cave is taboo,
0:12:51 > 0:12:55'the importance of Shane's work here is well recognised.'
0:12:55 > 0:12:58THEY SPEAK IN LOCAL DIALECT
0:13:02 > 0:13:05So I'm allowed to take my measuring instruments down.
0:13:05 > 0:13:08OK. Just don't take part of my breakfast down.
0:13:08 > 0:13:11- Yeah.- Otherwise I'm going to be suspecting your motives.
0:13:17 > 0:13:21'Shane's convinced Harry is talking about a volcanic vent.
0:13:21 > 0:13:24'A deep crack in the earth which is releasing
0:13:24 > 0:13:26'potentially-deadly amounts of carbon dioxide.
0:13:28 > 0:13:33'If he's right, it could be a clue to Marum's current behaviour.'
0:13:42 > 0:13:45Do you think this is it here, Shane, in front of us?
0:13:46 > 0:13:49- I think this is the place. - Oh, wow!- It looks like it.
0:13:49 > 0:13:50Oh, horrible!
0:13:50 > 0:13:51LAUGHTER
0:13:51 > 0:13:54Oh! Jeepers! That's strong.
0:13:54 > 0:13:57So clearly, there is something amiss here.
0:13:57 > 0:14:01There are a lot of dead birds in the cave.
0:14:04 > 0:14:07So that's drawing the gas in and over this tube.
0:14:07 > 0:14:10Yeah. And we see we've just gone down to the five,
0:14:10 > 0:14:12or just beyond the five, probably about 6%.
0:14:12 > 0:14:16Yeah. Which I have to say doesn't sound that high,
0:14:16 > 0:14:19but what are sort of normal levels of carbon dioxide?
0:14:19 > 0:14:22- It's more than ten times normal levels.- Wow! OK.- Yeah.
0:14:25 > 0:14:26So tell us what that one says.
0:14:29 > 0:14:32It looks much the same. Maybe even a tiny bit higher.
0:14:32 > 0:14:34- Oh, yeah. - Yeah. It's gone quite a bit more.
0:14:34 > 0:14:37- It's ten. It's turned to ten. - That looks like ten. Yeah.
0:14:37 > 0:14:38Yeah. Wow!
0:14:38 > 0:14:40So I suppose because it's a heavier gas...
0:14:40 > 0:14:42It's sunk down. Yeah.
0:14:42 > 0:14:44I'm going to have to move.
0:14:44 > 0:14:47That's enough to kill you pretty quickly, actually. 10%.
0:14:47 > 0:14:51And could that be a precursor to a bigger eruptive event?
0:14:51 > 0:14:54Yeah. We would need to measure this constantly
0:14:54 > 0:14:57and know whether this gets more or less.
0:14:57 > 0:15:01But definitely, this would be a place where regular monitoring,
0:15:01 > 0:15:04if there was a big spike in the carbon dioxide output here,
0:15:04 > 0:15:08it would be worth definitely warning people.
0:15:08 > 0:15:11Presumably, if that much carbon dioxide is being pumped out of here,
0:15:11 > 0:15:14standing around here for much longer is not a good idea.
0:15:14 > 0:15:17No, I don't think it's a good idea for us to be overnighting here!
0:15:17 > 0:15:18LAUGHTER
0:15:22 > 0:15:25'The surprisingly high levels of carbon dioxide suggest
0:15:25 > 0:15:28'that magma is rising from deep below,
0:15:28 > 0:15:31'making the threat of a big eruption more likely.
0:15:33 > 0:15:37'It's enough to make me a bit nervous about what we might find
0:15:37 > 0:15:40'when we reach the summit in a few days' time.
0:15:55 > 0:15:58'Whilst Chris and Shane prepare their kit for the trek up...
0:16:00 > 0:16:02'..I'm heading to an annual ritual
0:16:02 > 0:16:05'that I've been told I just shouldn't miss.
0:16:11 > 0:16:14'The rugged volcanic landscape and old lava flows
0:16:14 > 0:16:16'separate the villages here.
0:16:16 > 0:16:20'So even on this small island, four different languages are spoken.
0:16:23 > 0:16:27'But shared systems of trade and barter bind everyone together.'
0:16:29 > 0:16:31- The pigs' food is still here.- OK.
0:16:31 > 0:16:33So she wants to call them in here.
0:16:33 > 0:16:35OK. She's going to call them to the house?
0:16:35 > 0:16:38- Yeah, to the house.- Really?- Yeah.
0:16:38 > 0:16:40'And like all over Vanuatu,
0:16:40 > 0:16:43'it's based around pigs, which are also used as currency.'
0:16:43 > 0:16:47So people live really closely with pigs, almost as if they are part of the family.
0:16:47 > 0:16:51Particularly the pigs that start being reared for custom ceremonies.
0:16:54 > 0:16:57'On Ambrym, pigs also play a fundamental role
0:16:57 > 0:16:59'in the way society works.'
0:17:03 > 0:17:05Let's just have a little piggy moment.
0:17:05 > 0:17:08Let's just have a little piggy moment.
0:17:08 > 0:17:09Look how handsome you are.
0:17:09 > 0:17:12'Pigs are used to change social status
0:17:12 > 0:17:15'and their value depends on their tusks.'
0:17:16 > 0:17:18So pigs are ranked according
0:17:18 > 0:17:21to the level by which their tusks are grown.
0:17:21 > 0:17:23So the most valuable pig will have the tusk
0:17:23 > 0:17:27that's gone round two, sometimes even three times.
0:17:27 > 0:17:30So it will go through the cheek,
0:17:30 > 0:17:32- into the jaw and come back out again?- Yes.
0:17:32 > 0:17:36This is the kind of pig that you would use if you were taking a rank
0:17:36 > 0:17:39in the ceremonial rituals of status alteration
0:17:39 > 0:17:41which men go through to gain rank
0:17:41 > 0:17:44- in the sort of hierarchy of the village.- OK.
0:17:45 > 0:17:48'Once its tusks have curled sufficiently,
0:17:48 > 0:17:50'Janic is hoping to exchange his pig
0:17:50 > 0:17:53'either for a bride, or for a new title
0:17:53 > 0:17:57'so he can move up a rung in the island's social hierarchy.
0:17:59 > 0:18:02'This grade system is called the Maghe.
0:18:02 > 0:18:05'In spite of embracing other aspects of the modern world,
0:18:05 > 0:18:08'it's a custom that's still preserved.
0:18:08 > 0:18:11'Public ceremonies take place once a year.'
0:18:11 > 0:18:13TRIBAL SINGING
0:18:25 > 0:18:28What we are seeing now is a tamoke dance.
0:18:28 > 0:18:32So the tamoke dance is a spirit that dances through the village.
0:18:32 > 0:18:35Is that the people that have got the masks?
0:18:35 > 0:18:37- With the banana leaves. - With the banana leaves, yeah.
0:18:37 > 0:18:40They use it as an opening for the Magi,
0:18:40 > 0:18:42which is the system by which
0:18:42 > 0:18:45men will go through a series of different ranks.
0:18:45 > 0:18:48And their status will get higher and higher as they do that.
0:18:54 > 0:18:57'This is the grade taking ceremony.
0:18:57 > 0:19:00'The chief is going to assume one of 15 different grades.
0:19:04 > 0:19:07'Each level brings men closer and closer to immortality
0:19:07 > 0:19:11'and to the ancestors that reside in the volcano.'
0:19:12 > 0:19:15You hear about some men who are so high ranking,
0:19:15 > 0:19:18they do mortuary ceremonies for them before they die
0:19:18 > 0:19:21because they have almost passed over into the upper realm.
0:19:24 > 0:19:26'The chief is pelted with stones
0:19:26 > 0:19:29'as a way to display his strength and agility.
0:19:29 > 0:19:31'But to get his new title,
0:19:31 > 0:19:35'he also has to hand over his most prized tusker pig
0:19:35 > 0:19:38'and supply another normal pig for slaughter
0:19:38 > 0:19:41'to show he can provide for his community.'
0:19:41 > 0:19:43SQUEALING
0:19:44 > 0:19:47So they have these big special clubs that you can see there.
0:19:47 > 0:19:50They should do it in one blow and then it's painless.
0:19:50 > 0:19:53I can't watch that, I'm afraid.
0:19:57 > 0:20:01'It's not until the pig is killed that the exchange is complete.
0:20:02 > 0:20:06'Ceremonies like this play a crucial role in safeguarding knowledge
0:20:06 > 0:20:09'and tradition for future generations.
0:20:10 > 0:20:14'And it's shown me a very different side to this island
0:20:14 > 0:20:16'and its volcano.'
0:20:20 > 0:20:23Marum is central to my whole journey on Ambrym,
0:20:23 > 0:20:26but it's really interesting having these two different
0:20:26 > 0:20:28approaches to understanding it.
0:20:28 > 0:20:35One is the geological, knowing what those forces are that drive it,
0:20:35 > 0:20:39knowing and trying to discover what sort of state of activity
0:20:39 > 0:20:41it's in now.
0:20:41 > 0:20:45But equally important, I'm beginning to realise, is the custom
0:20:45 > 0:20:51and tradition that's also wrapped up around this volcano.
0:20:51 > 0:20:55It's absolutely fundamental to the identity of this island
0:20:55 > 0:20:58and the people who created it.
0:21:03 > 0:21:08We've already gathered important evidence from one of the subterranean vents,
0:21:08 > 0:21:13but there's still vital data Shane wants to collect before
0:21:13 > 0:21:18we set off for the volcano itself and descend into its heart.
0:21:18 > 0:21:24Something I'm in two minds about - both excited and frankly terrified.
0:21:27 > 0:21:28That cave that we went to,
0:21:28 > 0:21:32I'm pretty sure that there will be hundreds of those along the coast.
0:21:32 > 0:21:35There must be. There can't be an isolated one.
0:21:37 > 0:21:40While the rivers of molten rock that come with major
0:21:40 > 0:21:42eruptions are destructive and deadly,
0:21:42 > 0:21:46they're not the only danger Marum poses to the islanders.
0:21:46 > 0:21:51Its permanently bubbling lava lake brings another equally lethal
0:21:51 > 0:21:54threat, in the form of its gas plume,
0:21:54 > 0:21:57so large, it's visible from space.
0:21:59 > 0:22:02We're on our way to a village on the west of the island.
0:22:02 > 0:22:06It's an area plagued by the deadly concoction of gases that pour
0:22:06 > 0:22:08out of the volcano.
0:22:09 > 0:22:13So, here we are with these beautiful green hills in the foreground, all
0:22:13 > 0:22:16the jungles growing there, it's like the Garden of Eden,
0:22:16 > 0:22:20and then the hill beyond - there's no vegetation on those upper slopes.
0:22:20 > 0:22:22It's not altitude controlled.
0:22:22 > 0:22:26It's controlled by the acidic gases, particularly, that are raining
0:22:26 > 0:22:31out from that cloud and constantly killing all the vegetation.
0:22:31 > 0:22:34So the reason there's no vegetation up there is simply
0:22:34 > 0:22:37- because of the gas. - It's basically because of the gas.
0:22:37 > 0:22:39It's killing all the trees.
0:22:39 > 0:22:42The people living in and around this area are constantly having to
0:22:42 > 0:22:45deal with this acid rain and acid gas situation.
0:22:52 > 0:22:56Volcanic ash creates some of the most fertile soil in the world.
0:22:57 > 0:23:02But the toxic gases seep into the soil and into the water.
0:23:06 > 0:23:13This village happens to be right on the axis of activity.
0:23:13 > 0:23:17'We've come to Lolibulo, where in 2005, people were evacuated
0:23:17 > 0:23:18'because of the huge amounts
0:23:18 > 0:23:21'of toxic gas that was pumping out of Marum.'
0:23:23 > 0:23:27When it rained, and the rain then washes through the plume,
0:23:27 > 0:23:30and it takes with it sulphur, fluorine...
0:23:30 > 0:23:36'Fluorine is good for teeth, in small quantities, but too
0:23:36 > 0:23:41'much causes severe tooth decay and debilitating brittle bone disease.
0:23:41 > 0:23:45'Shane regularly tests the water here.'
0:23:47 > 0:23:48Fill that up.
0:23:53 > 0:23:58Stick one of these tablets in each of the...
0:23:58 > 0:24:02- One for you, one for me. - What do these do?
0:24:02 > 0:24:05We're going to change the chemistry of the water
0:24:05 > 0:24:08and if there's fluorine in here, it will react.
0:24:08 > 0:24:10Crush that bottom.
0:24:11 > 0:24:15So, have there been, in the past,
0:24:15 > 0:24:18very high incidences of children
0:24:18 > 0:24:21in this village with evidence of brittle bones and bad teeth?
0:24:21 > 0:24:23That kind of thing?
0:24:23 > 0:24:26In this village and the villages nearby, there was
0:24:26 > 0:24:29a really high incidents of chronic dental fluorosis, which is
0:24:29 > 0:24:33a strong indicator that there's bone issues as well.
0:24:35 > 0:24:37- Our first result's here.- OK.
0:24:37 > 0:24:40- So, we've got a reading of...- 2.6.
0:24:40 > 0:24:422.6.
0:24:42 > 0:24:44The second one...
0:24:46 > 0:24:48- 2.72.- 2.72.
0:24:48 > 0:24:51- So...- Wow! Almost identical. - Almost identical.
0:24:51 > 0:24:55What would normal levels be in clean or unadulterated rainwater?
0:24:55 > 0:24:58- Clean rainwater should have nothing. - Wow! OK.
0:24:58 > 0:25:03- Should have more or less nothing.- OK. I mean, is this health threatening?
0:25:03 > 0:25:06This is... This is, in chronic terms, yes, so it's too high.
0:25:06 > 0:25:08It's way too high.
0:25:08 > 0:25:11More than twice as much as it should be.
0:25:14 > 0:25:17It's shocking to discover how contaminated
0:25:17 > 0:25:19the water in this village is.
0:25:21 > 0:25:25While the people can reap the benefits of the fertile soil,
0:25:25 > 0:25:29the plume of gas they live beneath is more noxious than
0:25:29 > 0:25:30the air in any city.
0:25:43 > 0:25:45The team on the summit is almost ready for us,
0:25:45 > 0:25:49but the weather up there has been wildly fluctuating.
0:25:49 > 0:25:54Driving rain and strong winds would at the moment make any
0:25:54 > 0:25:58attempt to descend into the crater impossible.
0:25:58 > 0:26:02All we can do is hope that things change before we set off.
0:26:14 > 0:26:18In the meantime, I want to go in search of some unusual
0:26:18 > 0:26:22wildlife that takes advantage of conditions on the island.
0:26:28 > 0:26:33The megapode is a rare bird which incubates its eggs in the warm
0:26:33 > 0:26:35volcanic soils.
0:26:38 > 0:26:43So, with my expert guide George, I'm on the hunt for eggs.
0:26:43 > 0:26:47So, what are the signs that we're looking for.
0:26:47 > 0:26:50- These birds are quite clever.- OK.
0:26:50 > 0:26:53They usually come up last over the nest.
0:26:53 > 0:26:57We can tell if there's lots of leaves and rotting wood
0:26:57 > 0:27:00and the ground is soft...
0:27:00 > 0:27:01Ah! OK.
0:27:01 > 0:27:05'Megapodes are endangered, so to protect them,
0:27:05 > 0:27:08'it's taboo to collect their eggs,
0:27:08 > 0:27:11'except at certain times of the year.'
0:27:11 > 0:27:16It sort of...doesn't feel that warm, actually. I'm surprised.
0:27:16 > 0:27:19- It will get warmer.- It will?- Yeah.
0:27:19 > 0:27:22- Ooh! What's that?- That's it!
0:27:22 > 0:27:24Look at the size of it!
0:27:24 > 0:27:27Before we pull it out, let's take a temperature reading,
0:27:27 > 0:27:29cos I don't think it feels very warm.
0:27:31 > 0:27:3429.9,
0:27:34 > 0:27:38which doesn't seem warm enough, but usually across the Pacific,
0:27:38 > 0:27:41for them to successfully incubate,
0:27:41 > 0:27:45people have found that the temperature is around 33 degrees, so
0:27:45 > 0:27:48I would say that's maybe a bit too cool,
0:27:48 > 0:27:50but do you sometimes find eggs that won't hatch?
0:27:50 > 0:27:53- We find lots of eggs that don't hatch.- OK.
0:27:53 > 0:27:56- And they stink.- Oh, really? - Very smelly.
0:27:56 > 0:27:58Let me take it out now.
0:27:58 > 0:28:00Oh, my goodness!
0:28:00 > 0:28:02Look at that!
0:28:03 > 0:28:07Look at the extraordinary shape and weight of this egg.
0:28:07 > 0:28:10It's really, really heavy.
0:28:10 > 0:28:15And if this egg were allowed to go through its full incubation
0:28:15 > 0:28:17period of about, of about 60 days,
0:28:17 > 0:28:23what would happen is that the chick very well fed on that enormous yolk,
0:28:23 > 0:28:26would use its feet to break out of the shell
0:28:26 > 0:28:30and then burrow up through the ground... That's right, isn't it?
0:28:30 > 0:28:33And then it will emerge fully-feathered
0:28:33 > 0:28:38and within 24 hours will be able to be completely independent.
0:28:38 > 0:28:42- Do you think there's going to be more?- I think there should be more.
0:28:44 > 0:28:47- God! They go right in, don't they?- It does!
0:28:51 > 0:28:53Maybe it's too far.
0:28:53 > 0:28:56George, you know... You're talking to a girl who likes a challenge.
0:28:56 > 0:28:58Ha-ha!
0:28:58 > 0:29:03OK. So, you might have to drag me out here. Ha-ha!
0:29:03 > 0:29:07'The eggs are often buried two metres deep.
0:29:07 > 0:29:10'And these birds have done such a good job that our attempts to
0:29:10 > 0:29:14'reach them make the entire bank unstable.'
0:29:14 > 0:29:17Oh, my God! It's really warm, George!
0:29:17 > 0:29:18- Argh!- Whoa!
0:29:21 > 0:29:23- Are you all right?- Yes. I'm fine!
0:29:23 > 0:29:24SHE LAUGHS
0:29:24 > 0:29:28I don't know why they don't just go to the
0:29:28 > 0:29:30supermarket like everybody else!
0:29:30 > 0:29:32Oh, George! Tell you what...
0:29:32 > 0:29:37That's one of the difficulties of harvesting the eggs...
0:29:37 > 0:29:41- Even though they're delicious... - Have the soil land on your head!
0:29:41 > 0:29:45Even though they're delicious, it's hard to get them.
0:29:45 > 0:29:47We'll be lucky...
0:29:47 > 0:29:49- Lucky.- God! I can't see a thing!
0:29:52 > 0:29:55'It probably serves me right for disturbing the nest.
0:29:55 > 0:29:57'I only hope the eggs are worth it.'
0:30:00 > 0:30:02Asbestos fingers.
0:30:02 > 0:30:04Also one thing about this egg.
0:30:04 > 0:30:09It doesn't peel off nice and clean like a chicken egg.
0:30:09 > 0:30:10OK.
0:30:10 > 0:30:14So, all in all, you nearly die when you collect them.
0:30:15 > 0:30:17When you cook them, they might be rotten.
0:30:17 > 0:30:19They might be rotten.
0:30:19 > 0:30:20- They don't peel easily.- No.
0:30:20 > 0:30:23I hope they taste really good!
0:30:23 > 0:30:24You'll soon find out.
0:30:24 > 0:30:26- Just dip in like that? - Just dip in.
0:30:33 > 0:30:36That's delicious, isn't it?
0:30:36 > 0:30:39It's incredible to see how these extraordinary birds
0:30:39 > 0:30:42have adapted to their environment, and it's another reminder
0:30:42 > 0:30:47of how the volcano shapes life on every single part of this island.
0:30:55 > 0:30:58The time has finally come to head up to the summit
0:30:58 > 0:31:01and to meet Marum face to face.
0:31:17 > 0:31:21- OK. Ready to roll? - Yeah, OK.- Let's go.
0:31:22 > 0:31:24It's early morning
0:31:24 > 0:31:26and although the weather is fine down here,
0:31:26 > 0:31:29it's no indication of what it might be like at the top.
0:31:32 > 0:31:34Is that your water bottle?
0:31:34 > 0:31:35Straight up? No?
0:31:38 > 0:31:39Off we go.
0:31:48 > 0:31:52The first half of the trek takes us through dense jungle.
0:31:52 > 0:31:55It's hot and humid, but thanks to our local guides
0:31:55 > 0:31:58Robert and Janic, we get some inside knowledge into
0:31:58 > 0:32:02the rainforest's weird and wonderful natural resources.
0:32:05 > 0:32:08Do you want to try some juice out of a vine?
0:32:08 > 0:32:10- Yeah!- Yeah, yeah.
0:32:15 > 0:32:18- Isn't that incredible?- Yeah. - Tastes lovely as well, doesn't it?
0:32:18 > 0:32:20That sort of slightly fresh, woody taste.
0:32:25 > 0:32:27After four strenuous hours,
0:32:27 > 0:32:30we've climbed almost 1000 metres above sea level
0:32:30 > 0:32:32and the path is getting steeper.
0:32:35 > 0:32:38You can see how narrow the ridge is.
0:32:38 > 0:32:40It's just like a knife edge, isn't it?
0:32:40 > 0:32:42- Yeah, yeah, this is the right one! - I tell you what,
0:32:42 > 0:32:45I'm very pleased it's as vegetated as this
0:32:45 > 0:32:48otherwise it would be very scary indeed!
0:32:53 > 0:32:57Eventually, we catch our first glimpse of Marum in the distance.
0:32:57 > 0:33:01If you look through there, you can see Marum, not very well, but...
0:33:01 > 0:33:05- Just that sort of dark patch through the trees? - Yeah, that's it.- Wow. OK.
0:33:07 > 0:33:10It's a welcome boost for the final leg of our journey.
0:33:12 > 0:33:17But there's an important ritual Janic tells us we have to carry out
0:33:17 > 0:33:19before we can go any further.
0:33:19 > 0:33:20Before we go down to the ash plane
0:33:20 > 0:33:24each one of you has to carry their each own bamboo.
0:33:24 > 0:33:28- OK.- So you go down and each one, you throw the bamboo to the ash plane
0:33:28 > 0:33:32before all of us go all about the ash plane.
0:33:32 > 0:33:34- OK.- I mean only....
0:33:34 > 0:33:36Ah, OK.
0:33:36 > 0:33:39- Because you're an old hand you don't need to put one down?- Yeah, yeah.
0:33:39 > 0:33:41- I think you should, though. - Well, maybe.
0:33:41 > 0:33:43HE SPEAKS TO GUIDE IN LOCAL LANGUAGE
0:33:43 > 0:33:46If it rains and there's a howling gale, I'll blame you!
0:33:48 > 0:33:50- Whoop! Nearly did it!- Yeah.
0:33:51 > 0:33:54- Is this the ash plane? - Yeah, this is the ash plane.
0:33:54 > 0:33:55So before we go down on the ash plane...
0:33:55 > 0:33:58Yeah? This is where you have to throw it?
0:33:58 > 0:34:00- Just throw the bamboo.- OK, so from here?- From here.
0:34:02 > 0:34:06Throwing bamboo onto the ash plain is an ancient ritual
0:34:06 > 0:34:10to appease the volcano's spirits and keep us safe.
0:34:10 > 0:34:14It's a reminder that we have to treat Marum with great respect.
0:34:18 > 0:34:20Yeah, it's quite different here now.
0:34:23 > 0:34:27After the dense forest, our journey takes us across an epic moonscape
0:34:27 > 0:34:31into the volcano's outer crater - its caldera.
0:34:32 > 0:34:35From here, we begin our final ascent.
0:34:36 > 0:34:39- Lot of smoke coming out of the crater now, we can say.- Yeah.
0:34:41 > 0:34:44- You can just see that line, with the wind.- Yeah, yeah.
0:34:53 > 0:34:54OK, as far as ridges go...
0:34:57 > 0:35:00- ..how extreme is this one? - This is the last one.
0:35:00 > 0:35:03OK. Damn it, thought you were going to say, "You're doing fine".
0:35:03 > 0:35:05You're doing fine!
0:35:05 > 0:35:06KATE LAUGHS
0:35:09 > 0:35:11You're going to cause a landslide!
0:35:13 > 0:35:16Oh, Robert, you and I are going to come up at a sedate
0:35:16 > 0:35:19and sensible pace.
0:35:21 > 0:35:23Oh, my God, this is quite scary!
0:35:23 > 0:35:25KATE LAUGHS
0:35:25 > 0:35:27Eventually, after almost eight hours,
0:35:27 > 0:35:30it's the moment we've all been waiting for.
0:35:31 > 0:35:34- Whoo!- Yes!- Oh, my God! Oh!
0:35:34 > 0:35:37Oh, my...!
0:35:37 > 0:35:38KATE GASPS
0:35:41 > 0:35:42Amazing, isn't it?
0:35:42 > 0:35:44It's just...
0:35:44 > 0:35:46I can't believe what a clear view we're getting of it.
0:35:46 > 0:35:49It's just kicking up onto the top of that ledge!
0:35:49 > 0:35:50Yeah, yeah, that's amazing.
0:35:52 > 0:35:56There's something really kind of inexplicable about
0:35:56 > 0:36:00looking at a sight like that, because it's so unfamiliar.
0:36:00 > 0:36:05This isn't something that your kind of normal life computes.
0:36:05 > 0:36:09It's just this sort of astonishing energy.
0:36:09 > 0:36:14This kind of boiling, seething energy that looks like
0:36:14 > 0:36:16it just wants to kind of leap up the mountain.
0:36:16 > 0:36:20It looks to me, Shane, this is a precursor to it just going, "Woof!"
0:36:20 > 0:36:22Oh, yeah.
0:36:22 > 0:36:24"Oh, yeah", he says as we stand on the edge!
0:36:24 > 0:36:27We're looking so far down. I mean, that's splashing up a long way.
0:36:27 > 0:36:28LOW RUMBLING
0:36:28 > 0:36:32- This is much, much higher than I've seen it for a long time.- OK.
0:36:36 > 0:36:40This is one of just five lava lakes in the whole world
0:36:40 > 0:36:43and Shane is immediately struck by how much bigger
0:36:43 > 0:36:47and more vigorous it is than when he was last here three years ago.
0:36:51 > 0:36:54To find out why, we need to get much closer.
0:36:54 > 0:36:57Shane and Chris want to collect rock and gas samples
0:36:57 > 0:37:00from as near to the lake as possible.
0:37:01 > 0:37:03It's now all down to the weather.
0:37:07 > 0:37:10The weather up here for the last three days
0:37:10 > 0:37:15has been spectacularly bad. The team who have been setting up camp
0:37:15 > 0:37:19and rigging everything for us have been on the sat phone
0:37:19 > 0:37:23and all they could hear was just pounding rain and howling,
0:37:23 > 0:37:25howling winds.
0:37:25 > 0:37:31So, to get up here in these relatively benign conditions
0:37:31 > 0:37:33feels incredibly lucky.
0:37:34 > 0:37:38How long it will last, nobody knows.
0:37:42 > 0:37:44Hi, welcome to mountain camp.
0:37:44 > 0:37:47Here to meet us is intrepid adventurer Geoff Mackley...
0:37:47 > 0:37:48You must be Kate.
0:37:48 > 0:37:50I am. Are you Geoff?
0:37:50 > 0:37:51Welcome to Fire Mountain!
0:37:51 > 0:37:53I need to hug you!
0:37:53 > 0:37:57..and my long-time friend, climbing expert Tim Fogg.
0:37:57 > 0:38:00- Lovely walk.- It's good, isn't it? - Isn't it beautiful?- Spectacular.
0:38:00 > 0:38:04Together, they'll help us collect the samples we need.
0:38:04 > 0:38:05Hi, Gareth, good to see you.
0:38:05 > 0:38:08You've got a dog in camp. That makes me feel I'm going to be able
0:38:08 > 0:38:10to cope with almost anything.
0:38:10 > 0:38:14We hope this team will be able to keep us safe.
0:38:14 > 0:38:16Rusty! What you doing?
0:38:18 > 0:38:23If all goes well, tomorrow we'll be descending into this fiery cauldron
0:38:23 > 0:38:25with nothing between us and this blistering,
0:38:25 > 0:38:28100-metre wide lake of lava.
0:38:33 > 0:38:37But with so much to do, Shane wastes no time.
0:38:37 > 0:38:40He immediately gets cracking with his thermal imaging camera
0:38:40 > 0:38:44to find out how hot and how dynamic the lava is.
0:38:50 > 0:38:54It's the most glorious night,
0:38:54 > 0:38:56almost no wind, and we're getting
0:38:56 > 0:39:00some of the clearest views of the crater that we've had
0:39:00 > 0:39:03since we've been up here.
0:39:03 > 0:39:06- That's a fantastic image, isn't it? - It's amazing, isn't it?
0:39:06 > 0:39:09Look at the different temperatures across the thing.
0:39:09 > 0:39:13- We're measuring 1013, so it's pretty hot down there.- Wow. It is.
0:39:13 > 0:39:17So this temperature jumping around is measuring the highest point
0:39:17 > 0:39:19of the lake at this precise moment.
0:39:19 > 0:39:22The highest temperature of the lake at this precise moment.
0:39:22 > 0:39:24Look at it splashing.
0:39:24 > 0:39:28I mean, it does seem particularly furious tonight.
0:39:28 > 0:39:33Will this camera also be able to help you to establish the rhythm
0:39:33 > 0:39:37and frequency of these pulses of what appears to be new lava
0:39:37 > 0:39:41constantly cycling back up to the surface?
0:39:41 > 0:39:45I think it's going to be a really good indication of the size
0:39:45 > 0:39:48of the reservoir, because if you've got a small pot
0:39:48 > 0:39:50that's continually churning
0:39:50 > 0:39:52then obviously it will cool down -
0:39:52 > 0:39:55but we've got constant temperatures.
0:39:55 > 0:39:57Frequently over 1,000, isn't it?
0:39:57 > 0:39:59And as you say, at this distance,
0:39:59 > 0:40:02to measure radiant heat of that magnitude
0:40:02 > 0:40:04is extraordinary and terrifying, really.
0:40:06 > 0:40:08It's amazing, isn't it?
0:40:08 > 0:40:10It really does look furious tonight.
0:40:10 > 0:40:13- It does, it looks like a real hell's cauldron down there.- Yeah!
0:40:14 > 0:40:16FIERCE RUMBLING
0:40:16 > 0:40:22The readings reveal an extraordinary 60% increase in the lava lake's
0:40:22 > 0:40:25heat and energy since Shane was last here.
0:40:25 > 0:40:29And this suggests that more magma is welling up from deep below,
0:40:29 > 0:40:32priming Marum to become much more active.
0:40:44 > 0:40:50It's a slope of, I'd guess around 50 degrees, that swaps from...
0:40:50 > 0:40:54At daybreak, climbing expert Tim gathers us all together
0:40:54 > 0:40:56for our first briefing.
0:40:56 > 0:40:58And it's not good news.
0:40:58 > 0:41:01- The weather's not great.- No.
0:41:01 > 0:41:05The horrible thing about it, is when it rains,
0:41:05 > 0:41:08it's not normal rain, it's acid rain
0:41:08 > 0:41:11and it's quite surprising how it starts to sting your eyes
0:41:11 > 0:41:13and your skin starts to feel a bit funny.
0:41:13 > 0:41:16You can't just get off and go inside.
0:41:16 > 0:41:19You're stuck, you're in there for hours and hours.
0:41:19 > 0:41:22Just staying down there and waiting out the rain,
0:41:22 > 0:41:24really, is a pretty horrible option.
0:41:28 > 0:41:32The awful weather means it's just not safe to descend today.
0:41:32 > 0:41:36It's a huge disappointment, and, with so little time,
0:41:36 > 0:41:39all we can do is hope it gets better.
0:41:46 > 0:41:48These really fine layers...
0:41:48 > 0:41:51But there's still plenty to we can do - so Shane and I
0:41:51 > 0:41:56are heading into the densest part of the gas plume to take some measurements.
0:41:58 > 0:42:00You need a clear sky above the gas.
0:42:00 > 0:42:03Do you think it's looking clear enough?
0:42:03 > 0:42:05Well, we're starting to get some good, blue sky.
0:42:05 > 0:42:09- The plume is pretty thick but we'll have a go.- OK.
0:42:09 > 0:42:11Shall we use this rock here?
0:42:11 > 0:42:13This looks like a good spot to set up.
0:42:13 > 0:42:15Just in front of the ash, yeah.
0:42:15 > 0:42:18So the last time you were here in 2012,
0:42:18 > 0:42:21- presumably you took gas measurements then.- Yep.
0:42:21 > 0:42:24If they're higher than they were then,
0:42:24 > 0:42:27what will it tell you about the volcano now?
0:42:27 > 0:42:33Yeah, I think, if they're going up, it's telling us that there's perhaps
0:42:33 > 0:42:37either more material coming into the deeper magma system
0:42:37 > 0:42:41and that gas is bubbling through, or it could mean we're getting
0:42:41 > 0:42:43deeper magma that is on its way up
0:42:43 > 0:42:47and that would probably herald a new phase of greater activity.
0:42:51 > 0:42:54Sort of the little sticks. Just keep going through there.
0:42:54 > 0:42:57So we're starting to track some numbers. Yeah, look at that.
0:42:57 > 0:43:01It's starting to creep up, basically just as the wind blows across.
0:43:01 > 0:43:04We're up to 400 now so I'm thinking we're going to get some
0:43:04 > 0:43:07pretty high values once we start to get into the centre of the plume.
0:43:10 > 0:43:15The increasing levels of gas show that Marum has become much more active.
0:43:15 > 0:43:18If the figures reach as high as they were a decade ago,
0:43:18 > 0:43:22the islanders may need to be evacuated once more.
0:43:22 > 0:43:25But to get the complete story, we need that good weather
0:43:25 > 0:43:28so we can descend into the crater itself.
0:43:36 > 0:43:37Later that night
0:43:37 > 0:43:41Chris and Shane spot a strange pink glow half a mile from the camp.
0:43:42 > 0:43:45- It's incredible, isn't it? - That is really something.
0:43:45 > 0:43:49They suspect it could be a new lava lake.
0:43:50 > 0:43:52- Look at it really, really pulsing. - Yeah.
0:43:54 > 0:43:56It's partly obscured by gas
0:43:56 > 0:43:59but the thermal camera confirms their suspicions,
0:43:59 > 0:44:02revealing an entirely different lava lake,
0:44:02 > 0:44:09one that was last active just before the devastating gas plume in 2005.
0:44:09 > 0:44:11- That's beautiful, isn't it?- Yeah!
0:44:13 > 0:44:17It's a dramatic turn of events, all adding up to suggest
0:44:17 > 0:44:21something momentous is happening deep inside the volcano.
0:44:41 > 0:44:44It's our final morning and we all nervously wait
0:44:44 > 0:44:46for a break in the weather.
0:44:47 > 0:44:50No-one wants to leave without the vital data.
0:44:51 > 0:44:55For me now being here, to have this opportunity,
0:44:55 > 0:44:57if the weather is kind,
0:44:57 > 0:45:01to get down, even part of the way,
0:45:01 > 0:45:06down into the crater of an incredibly active volcano
0:45:06 > 0:45:13is sort of equally terrifying but absolutely irresistible.
0:45:13 > 0:45:16It's irresistible. I have got to get down there.
0:45:22 > 0:45:26At last the sun puts in an appearance,
0:45:26 > 0:45:29it looks just about safe enough to risk it.
0:45:34 > 0:45:37The idea of hanging over a boiling lava lake seems
0:45:37 > 0:45:41more than a little crazy, but the rock and gas samples
0:45:41 > 0:45:45from deep inside the crater are the final pieces of the puzzle
0:45:45 > 0:45:49Shane needs to fully understand what this volcano is doing.
0:45:52 > 0:45:55- So are you ready to be a guinea-pig. - I am.
0:45:55 > 0:45:59These are like dip sticks in that they're a glass tube.
0:45:59 > 0:46:01- I'm going to break off the end.- Yes.
0:46:01 > 0:46:06And then during your descent and return over that period
0:46:06 > 0:46:11the gases you encounter will react with the chemical on the foam in here.
0:46:11 > 0:46:16- I'm going to put them facing downwards so we don't get ash in them.- OK.
0:46:16 > 0:46:18When you get back we'll take them off
0:46:18 > 0:46:21- and see how much gas you've been breathing.- Thank you!
0:46:21 > 0:46:23Right, where's Tim?
0:46:34 > 0:46:37- You want to squeeze that lever. - Right.
0:46:37 > 0:46:39Yeah?
0:46:39 > 0:46:42'Once we're clipped in there's no turning back.'
0:46:46 > 0:46:49'We plan to abseil down this near vertical drop
0:46:49 > 0:46:52'to a ledge above the boiling lake of lava.'
0:46:52 > 0:46:55This line pulls one, we're trying to fit two into it.
0:46:57 > 0:46:59- Shall I come back down? - Yeah, come on.
0:46:59 > 0:47:05'The tubes on my back should detect, the precise mix of gas coming off the lava lake.'
0:47:08 > 0:47:09Oh!
0:47:09 > 0:47:11Heart's racing.
0:47:16 > 0:47:17OK.
0:47:20 > 0:47:22Get it out of that groove.
0:47:27 > 0:47:32So, um, it's really hard to describe this feeling
0:47:32 > 0:47:39of descending to...well,
0:47:39 > 0:47:43certain death, obviously, if anything goes wrong
0:47:43 > 0:47:48but the exhilaration of doing something like this,
0:47:48 > 0:47:52it makes you feel very connected to the earth and how it works,
0:47:52 > 0:47:56if that makes any sort of sense at all.
0:47:56 > 0:47:59I have to confess that all I'm looking at, at the moment
0:47:59 > 0:48:01is my feet and Tim's feet.
0:48:01 > 0:48:04I haven't looked around me, I haven't looked at the view,
0:48:04 > 0:48:09I think if I did I would be stuck here forever more.
0:48:09 > 0:48:12We've got one of these steps again, one of these vertical bits.
0:48:12 > 0:48:14'The heat from the lake is intense.
0:48:14 > 0:48:18'and the noxious gases mean we can't spend long here
0:48:18 > 0:48:19'so we have to move fast.
0:48:19 > 0:48:24'but the crumbling rocks, make it difficult to get a foothold.'
0:48:25 > 0:48:27Lean back, feet apart.
0:48:27 > 0:48:29Legs straight as you can.
0:48:29 > 0:48:31Oh, sorry!
0:48:31 > 0:48:33- Oh, Tim, sorry!- OK, OK, no problem.
0:48:33 > 0:48:35I really did bash you. OK.
0:48:39 > 0:48:42- You can feel the heat now.- Yeah.
0:48:42 > 0:48:45I don't know whether it's just fear, sweat of fear and fear,
0:48:45 > 0:48:48or the heat of the lake itself.
0:48:48 > 0:48:52I can hear the sort of lava waves crashing.
0:48:52 > 0:48:56It really does feel like you're approaching
0:48:56 > 0:49:00some sort of extraordinarily angry sea.
0:49:04 > 0:49:07Gas is just one part of our quest.
0:49:08 > 0:49:12Shane also wants to collect rock samples from inside the crater.
0:49:12 > 0:49:16Just offer that to the next volcano god.
0:49:16 > 0:49:20Chris will analyse them to see if any of the newer lava
0:49:20 > 0:49:25has a similar composition to the lava from previous major eruptions.
0:49:25 > 0:49:31If so, it could mean Marum is heading for another big eruption.
0:49:31 > 0:49:32Come on!
0:49:36 > 0:49:38- Are we there?- Yes.
0:49:38 > 0:49:41Finally Tim and I reach the ledge we've been aiming for.
0:49:42 > 0:49:46The deafening roar of the boiling lava drowns out everything
0:49:46 > 0:49:50and the heat coming off the lake is almost overwhelming.
0:49:51 > 0:49:57What we'll do is to slowly adjust these knots so you can go forward.
0:49:57 > 0:49:59I don't want to go forward. I really don't.
0:49:59 > 0:50:02I really don't, I just... Not yet anyway. Let me...
0:50:02 > 0:50:03I've got you. I've got you.
0:50:03 > 0:50:06I know but I don't want to pull you over the edge, Tim.
0:50:06 > 0:50:08It's just so loose, this rock.
0:50:09 > 0:50:13'I'm clinging on for what feels like dear life,
0:50:13 > 0:50:18'but to get the best samples I have to get even closer to the edge.'
0:50:18 > 0:50:21- RADIO:- 'You go back to your left.'
0:50:21 > 0:50:24They don't want me right on the edge, do they?
0:50:24 > 0:50:25Right on the white rock?
0:50:28 > 0:50:30Yes, that way a bit more.
0:50:31 > 0:50:33Tim, you've got to be kidding me.
0:50:35 > 0:50:37Centimetre by centimetre towards the white rock.
0:50:48 > 0:50:50Oh, wow!
0:50:50 > 0:50:51OK.
0:50:54 > 0:50:57The cloud is cleared, Tim has forced me
0:50:57 > 0:51:01to move sideways across this slope,
0:51:01 > 0:51:03but it was absolutely worth it.
0:51:03 > 0:51:06We are now getting the most astonishing views
0:51:06 > 0:51:08of the lava lake.
0:51:08 > 0:51:12Furious boiling lake of molten rock.
0:51:12 > 0:51:18Now that we're this much closer it really does look like it could
0:51:18 > 0:51:21just explode up at any moment.
0:51:22 > 0:51:24Oh, that was a huge one.
0:51:25 > 0:51:31It really looks like it's barely able to suppress itself.
0:51:33 > 0:51:37It's sort of like witnessing the beginning of the Earth...
0:51:38 > 0:51:42..but it's the most astonishing feeling really,
0:51:42 > 0:51:46to be down the crater of a very active volcano,
0:51:46 > 0:51:48and these glass vials on my back
0:51:48 > 0:51:52that Shane put there will hopefully give him some sort of clues
0:51:52 > 0:51:56as how active this volcano really is at this very moment.
0:52:00 > 0:52:02The conditions are intense.
0:52:02 > 0:52:05The gas mask keeps out most of the noxious gases,
0:52:05 > 0:52:07but I can feel my throat burning
0:52:07 > 0:52:10and the heat is becoming unbearable.
0:52:11 > 0:52:15It's among the most amazing, terrifying
0:52:15 > 0:52:17and exhilarating two hours of my life.
0:52:22 > 0:52:26But I have to go while I've got the strength to get back to the top.
0:52:30 > 0:52:32Slide yourself up.
0:52:32 > 0:52:33Yep. Brilliant!
0:52:33 > 0:52:35Whoo!
0:52:38 > 0:52:40Wow!
0:52:40 > 0:52:43It looked furious, like we shouldn't have been there.
0:52:43 > 0:52:45It was like a warning,
0:52:45 > 0:52:49and then as we just sat a bit calmly and actually everything around
0:52:49 > 0:52:53started to clear, it's so magnificent it kind of takes your breath away.
0:52:53 > 0:52:56And the lake sort of calmed, it was almost like, you know,
0:52:56 > 0:52:59"Well, OK, you can hang around for a bit,"
0:52:59 > 0:53:03and then suddenly it was like this great burst of fury again,
0:53:03 > 0:53:07and really chucking lava out, you know, not just over the rim,
0:53:07 > 0:53:09but right up into the sky.
0:53:09 > 0:53:12And the coming up bit, you think, "Oh, it's going to be really easy.
0:53:12 > 0:53:14"I'll just lie back!" But it's not.
0:53:14 > 0:53:15I tell you what, my thighs are burning.
0:53:15 > 0:53:18But I'm desperate to know what's happened on the back?
0:53:18 > 0:53:20Are they still sitting there my little glass...?
0:53:20 > 0:53:22They're still there, they're still sitting there.
0:53:22 > 0:53:24Yes, and one of them's gone all yellow.
0:53:24 > 0:53:26Let's have a look.
0:53:26 > 0:53:28- Looks like you've had a bit of noxious gas?- Yes.
0:53:28 > 0:53:30And it's reacted yellow. This is SO2.
0:53:30 > 0:53:33- That's sulphur dioxide. - That's right.
0:53:33 > 0:53:35So you would expect a lot of that.
0:53:35 > 0:53:38Yes, because we've seen all that brown gas everywhere.
0:53:38 > 0:53:40- Do you see that slight pink colour? - Yes.
0:53:40 > 0:53:42- You haven't had much of that. - What's that?
0:53:42 > 0:53:44- That's HF. Ah, well!- What's HF?
0:53:44 > 0:53:47- Yeah, just as well. HF's pretty... - Oh, it's the really horrible, acidic one.
0:53:47 > 0:53:51- It's very, very poisonous. - Is that the hydrogen fluoride? - Exactly, yes.
0:53:51 > 0:53:54And presumably you're only able to get that reading because
0:53:54 > 0:53:56- we were, I was, I should say! - Because you went down there. Yes.
0:53:56 > 0:54:00- I was physically down there, much, much closer to the lake. - Closer, yeah.
0:54:00 > 0:54:02This is really quite spectacular.
0:54:05 > 0:54:08It's a huge relief that we're all back on solid ground.
0:54:10 > 0:54:12But there's no rest for Shane and Chris
0:54:12 > 0:54:14who head off to analyse their results.
0:54:17 > 0:54:20They need to compare the evidence we've found this time,
0:54:20 > 0:54:22to the data they already have
0:54:22 > 0:54:26from the large eruptions in 1989 and 2005.
0:54:31 > 0:54:37All I can do is wait to find out if we've uncovered Marum's secrets.
0:54:44 > 0:54:49Let's start with those gas results that you and I collected yesterday.
0:54:49 > 0:54:53We are getting 2,200 tonnes a day of sulphur dioxide.
0:54:53 > 0:54:56Now, in normal kind of conditions,
0:54:56 > 0:54:59say you were here in 2012, how did that compare?
0:54:59 > 0:55:04Yeah, so normal conditions like the last time for example, about 1,000.
0:55:04 > 0:55:08So it's over twice the amount of sulphur dioxide
0:55:08 > 0:55:09coming out of it now.
0:55:11 > 0:55:14The gas measurements Shane's taken across the island
0:55:14 > 0:55:18show the levels are rising towards those in 2005
0:55:18 > 0:55:22when toxic gas emissions led to widespread evacuations.
0:55:24 > 0:55:27And the rock samples have their own tale to tell.
0:55:29 > 0:55:32Certainly the analysis that we did,
0:55:32 > 0:55:35suggested that the activity that's occurring today
0:55:35 > 0:55:41is similar to the 2005 or the 1989 eruptions.
0:55:41 > 0:55:44So, the composition of the lava seems much like it was
0:55:44 > 0:55:48during the last two big eruptions.
0:55:49 > 0:55:53And then there's the unexpected discovery of the new lava lake.
0:55:55 > 0:55:57- I was blown away. - Yeah, it was an amazing experience.
0:55:57 > 0:56:00But surely, surely that,
0:56:00 > 0:56:04combined with the data that you've got,
0:56:04 > 0:56:08must indicate something, well, quite exciting
0:56:08 > 0:56:11with regards to the whole island's volcanic activity, doesn't it?
0:56:11 > 0:56:14Something's certainly on the go.
0:56:14 > 0:56:17You know, there's definitely, we're definitely double background level,
0:56:17 > 0:56:21so we're not just sitting there at normal level. Things are going up.
0:56:21 > 0:56:23Volcanoes are very unpredictable.
0:56:23 > 0:56:27We haven't had anything a big lava flow like 1989 for a while,
0:56:27 > 0:56:30so I would have said, yes, we're overdue for something like that.
0:56:38 > 0:56:40The evidence we've collected
0:56:40 > 0:56:44suggests something is stirring deep inside the heart of this volcano,
0:56:44 > 0:56:48bringing the threat of a big eruption ever closer.
0:56:49 > 0:56:53And our discoveries mean that Shane now feels there's enough evidence
0:56:53 > 0:56:56to increase Marum's level of risk on the international register.
0:56:58 > 0:57:01It's an early warning for the islanders to prepare
0:57:01 > 0:57:03should they have to evacuate.
0:57:08 > 0:57:13This has been the most astonishing journey
0:57:13 > 0:57:16around the volcanoes of Vanuatu.
0:57:18 > 0:57:21And to sit here now, looking down at
0:57:21 > 0:57:26Marum's magnificent lava lake boiling away,
0:57:26 > 0:57:30and to understand just a little bit more about its personality
0:57:30 > 0:57:35and to discover that we are potentially on the brink
0:57:35 > 0:57:38of a time of really heightened activity
0:57:38 > 0:57:41is tremendously exciting.
0:57:51 > 0:57:55'It's time to bid farewell to these breathtaking islands
0:57:55 > 0:57:57'and their spectacular volcanoes.'
0:57:57 > 0:57:59Oh, my goodness!
0:57:59 > 0:58:02Oh, it's so beautiful!
0:58:03 > 0:58:05'It is without question,
0:58:05 > 0:58:07'an experience I'll never forget.'
0:58:07 > 0:58:09Oh, my God!
0:58:11 > 0:58:14'And it's reassuring to know that the data we've collected
0:58:14 > 0:58:16and the knowledge we've gained
0:58:16 > 0:58:20will help to keep the people living here safe from harm.