0:00:00 > 0:00:03We're standing on the crater rim of the world's most active volcano.
0:00:03 > 0:00:08For 30 years lava has been spewing out a line of craters, engulfing
0:00:08 > 0:00:13homes and property, and in 2008, that crater exploded into action,
0:00:13 > 0:00:23forcing the closure of this park. Did does science know enough about
0:00:23 > 0:00:58
0:00:58 > 0:01:02volcanoes to keep us safe? This is Welcome back to a glorious morning
0:01:02 > 0:01:05here in Hawaii Volcanoes National Park. We are coming to you live
0:01:05 > 0:01:11from the middle of the Pacific. Let's just remind you where exactly
0:01:11 > 0:01:15we are. Now, we're on Big Island at the bottom of the Hawaiian
0:01:15 > 0:01:19archipelago right there on the rim of Kilauea. As I said at the
0:01:19 > 0:01:23beginning, the world's most active volcano. Yesterday we were at the
0:01:23 > 0:01:27coastal community of Kalapana, but what we did was we packed all our
0:01:27 > 0:01:30gear up. We moved the trucks. There you can see us moving across them
0:01:30 > 0:01:34taking little Minnie Winnie all the way up here to the summit to this,
0:01:35 > 0:01:39what's behind us here, which is the house of the eternal fire -
0:01:39 > 0:01:44Halema'uma'u Crater. The thing is, that giant plume of gas coming out
0:01:44 > 0:01:48there means we can't get any closer. Those plumes are toxic. Also, it's
0:01:48 > 0:01:51hard to see into the crater. Also, the cameras are going to show us
0:01:51 > 0:01:55the latest pictures. You can see from the camera at the top showing
0:01:55 > 0:02:00just what it looks like normally, then the thermal below shows the
0:02:00 > 0:02:05lava churning away. The heat is extraordinary - several hundred
0:02:05 > 0:02:08degrees Celsius. That's what is behind us. You can have your
0:02:08 > 0:02:14personal view of the Kilauea lava lake whrefr you like by going to
0:02:14 > 0:02:17our website, bbc.co.uk/volvanolive. We've got various links to various
0:02:17 > 0:02:24webcams on active volcanoes throughout the world, and also if
0:02:24 > 0:02:29you go on to our website, you can join a web chat with the Professor
0:02:29 > 0:02:32Jon Blundy from the University of Bristol. He'll be answering your
0:02:32 > 0:02:35questions throughout the show. We have been looking at how volcanoes
0:02:35 > 0:02:39work this week, haven't we? That's right, over the last three nights
0:02:39 > 0:02:43really and today as well, we have been looking at how volcanoes work
0:02:44 > 0:02:49and the processes that cause them to erupt, but tonight we're going
0:02:49 > 0:02:56to explain just how good are we at looking at how volcanoes and others
0:02:56 > 0:03:02like this have got in store for us. Tonight, a volcanic tragedy. My God.
0:03:02 > 0:03:08Look at that. I come face to face with the 2,000-year-old victims of
0:03:08 > 0:03:12Mount Vesuvius in Italy. I meet an Icelandic giant which could dwarf
0:03:12 > 0:03:17the eruption of Eyjafjallajokull. Ed Byrne gets creative with some
0:03:17 > 0:03:20balls in a rubbish bin to build a super-volcano. And the
0:03:20 > 0:03:30volcanologists who go to the ends of the earth in pursuit of the
0:03:30 > 0:03:30
0:03:30 > 0:03:34Now, our understanding of volcanoes has vastly improved in modern years.
0:03:34 > 0:03:38We know where all the active volcanoes are, and we know why they
0:03:38 > 0:03:42erupt, but the thing that really still scuppers us is when they're
0:03:42 > 0:03:45going to erupt and for how long. That's right. That's one of the big
0:03:45 > 0:03:49challenges is working out precisely when they're going to erupt, how
0:03:50 > 0:03:52big that eruption is going to be, and how long that's going to take -
0:03:52 > 0:03:57that's some of the key questions. What we're going to look at tonight
0:03:57 > 0:04:01is, if you like, some of the tools of the trade. How do we know if we
0:04:01 > 0:04:05take a volcano like this or others around the world, when trouble is
0:04:05 > 0:04:10brewing? Later on we're going to meet Professor Steve Anderson and
0:04:10 > 0:04:13his team who have been using cutting-edge technology to produce
0:04:13 > 0:04:193D images of the crater behind us that have never been seen before,
0:04:19 > 0:04:21so that's something very much to look forward to. Well, scientists
0:04:21 > 0:04:25from the Hawaiian Volcano Observatory - we can see it just
0:04:25 > 0:04:29over there perched on the edge of the crater - those scientists are
0:04:29 > 0:04:32looking for tell-tale signs of activity, and one of the things
0:04:33 > 0:04:35they're looking at is the gas. In the weeks before the eruption of
0:04:35 > 0:04:41that Halema'uma'u Crater, the gas levels just went through the roof,
0:04:41 > 0:04:44and what that - what it means is that constantly-building gas plume
0:04:44 > 0:04:50isn't just a health hazard for, it's one of the real indicators
0:04:50 > 0:04:56trouble is brewing. Let's have a look at this film.
0:04:56 > 0:05:00I'm Tamara Elias, and I work at Hawaiian Volcano Observatory
0:05:00 > 0:05:05monitoring and studying volcanic gases. The gases can give us
0:05:05 > 0:05:12information on what's happening beneath the volcano. It can give
0:05:12 > 0:05:17clues as to what the behaviour of the volcano might be. The volcano
0:05:17 > 0:05:22ash coming out of this vent has a variety of particles and gases. The
0:05:22 > 0:05:30visible part is mainly water vapour and tiny particle, but there's also
0:05:30 > 0:05:34a hat full of gases including sulphur dioxide gas, hydrogen
0:05:34 > 0:05:41fluoride, hydrogen fluoride, a little bit of carbon moniex I'd.
0:05:41 > 0:05:44It's a cocktail of gases. Volcanic gas are dissolved in magma, and
0:05:44 > 0:05:50different species of gases bubble out of the magma at different
0:05:50 > 0:05:53depths or pressures. One of the gases that's particularly useful is
0:05:53 > 0:05:57sulphur dioxide or SO2. Those emissions rise and fall with the
0:05:57 > 0:06:06activity of the volcano because it's emitted very close to the
0:06:06 > 0:06:13surface. We actually use a small spectrometre, an ultraviolet
0:06:13 > 0:06:21spectrometre system to measure how much sulphur dioxide gas is coming
0:06:21 > 0:06:26out. It is basically measuring light, and conveniently, sulphur
0:06:26 > 0:06:30dioxide gas absorbs you would a violet light effectively, so we can
0:06:30 > 0:06:40use that property to measure or calculate how much SO2 gas is
0:06:40 > 0:06:44
0:06:44 > 0:06:50We drive beneath the plume, and we measure the concentration of
0:06:50 > 0:06:55sulphur dioxide above us. It can be reasonably extreme. You would smell
0:06:55 > 0:07:04the SO2. You would taste the SO2, and you would feel it irritating
0:07:04 > 0:07:08your throat, but we use a gas mask in the car. In 2008, we started to
0:07:08 > 0:07:12see an increase in the sulphur dioxide gas that was being emitted
0:07:12 > 0:07:17here at the summit, and we started measuring amounts that were
0:07:17 > 0:07:23unprecedented in our era of making these measurements, and it let us
0:07:23 > 0:07:33know that an eruption could occur, and in March of 2008, this vent
0:07:33 > 0:07:35
0:07:35 > 0:07:40during this era. I think as humans, we believe that scenery is rather
0:07:40 > 0:07:49static. I think that working here, you can see that whole landscapes
0:07:49 > 0:07:54can change very quickly. She mentioned the gas level changes
0:07:54 > 0:07:58that accompanied that 2008 eruption, and just to put that into context,
0:07:58 > 0:08:02a normal baseline emission of sulphur dioxide from that volcano
0:08:02 > 0:08:08is about 200 tonnes a day, but just prior to the eruption of that lava
0:08:08 > 0:08:12lake, those levels went up ten times - 2,000 tonnes a day. And
0:08:12 > 0:08:17that hole in the ground is the biggest sulphur dioxide polluter in
0:08:17 > 0:08:21the US. Now, as we know, every so often Kilauea has these tantrums,
0:08:21 > 0:08:26and someone who knows that first hand is Mark Patrick, geologist at
0:08:26 > 0:08:30the HVO. I am going to show you some footage of an eruption of the
0:08:30 > 0:08:33fire fountain that went on in March 2011. You were there. What was it
0:08:33 > 0:08:37like? Of the two people there, you're the one on the left. What
0:08:37 > 0:08:40was that like? Yeah, it was speck hacktacular. It was really the
0:08:40 > 0:08:44highlight of my time here at the Hawaiian Volcano Observatory.
0:08:44 > 0:08:48don't seem too close. We're not, actually. And that is because it
0:08:48 > 0:08:52was so hot, it was just keeping you at this distance. It was like
0:08:53 > 0:08:57standing in front of an oven. look at if you're kind of - I don't
0:08:57 > 0:09:02know if this is the word - enjoying it. What you're trying to do is
0:09:02 > 0:09:06second-guess when the volcano is going to be active. We have seen
0:09:06 > 0:09:10you monitoring the lake levels and taum aura sniffing out the gas, but
0:09:10 > 0:09:14you all work together, right? and that's one of the good things
0:09:14 > 0:09:18about working at the observatory, we have all of these specialists
0:09:18 > 0:09:23based right there. I can go down the hall and talk to a seismologist
0:09:23 > 0:09:26or gas specialist. You need to pull it all together to get the big
0:09:26 > 0:09:30picture. You put most of your data on the web, and you have webcams
0:09:30 > 0:09:36where you encourage the public to have a look at the volcano. Are you
0:09:36 > 0:09:40not a little bit concerned all of that data will turn people into
0:09:40 > 0:09:45armchair volcanologists, maybe misinterpreting the data? Years ago
0:09:45 > 0:09:52when there was lots of data on the web, there was a concern about that
0:09:52 > 0:09:57but it's not a problem. The benefit there has been benefits of getting
0:09:57 > 0:10:01the public involved in all of that activity. All the ground tilts
0:10:01 > 0:10:05start to tell you trouble is afoot. How does that work? At some point
0:10:05 > 0:10:09you presumably have to tell the park officials, "Look, we think an
0:10:10 > 0:10:13eruption is likely." That must be a really tricky judgment call. It is.
0:10:13 > 0:10:17It can be. The trickiest part is we have these instruments, and we can
0:10:18 > 0:10:21track very well when things are ramping up, but the big question is
0:10:21 > 0:10:26what's going to be the breaking point? But we have - we look at did
0:10:26 > 0:10:32geological record for past insights on that and we look at all the data
0:10:32 > 0:10:34we can. I guess that's a problem the world over with those people
0:10:34 > 0:10:37observing volcanos? Absolutely. It's a universal challenge with
0:10:37 > 0:10:41volcanoes that you can track when things are increasing and building
0:10:41 > 0:10:44up, but it's knowing that critical point that is the challenge. Thank
0:10:44 > 0:10:48you very much, Matt. One of the things that's interesting is that
0:10:48 > 0:10:52monitoring gives you this really short-term baseline of a few
0:10:52 > 0:10:55decades. Sometimes that's not really enough to capture the
0:10:55 > 0:11:01behaviour of a volcano. That's where history comes in because
0:11:01 > 0:11:05history gives you the longer-term perspective on the capacity of a
0:11:06 > 0:11:10volcano. That's what I learned when I went off to the Roman town of
0:11:10 > 0:11:14Vesuvius. Mount Vesuvius in southern Italy -
0:11:14 > 0:11:21it's responsible for one of the most famous natural disasters in
0:11:21 > 0:11:26history. In 79 AD Vesuvius erupted in
0:11:26 > 0:11:30spectacular style blasting out a lethal cloud of ash and molten rock.
0:11:30 > 0:11:37The cloud grew to 30 kilometres in height, and the wind blew it
0:11:37 > 0:11:40straight to the Roman city of Pompeii. Three metres of ash and
0:11:40 > 0:11:47rock rained down on Pompeii. Buildings collapsed under the
0:11:47 > 0:11:52weight, and hundreds of people were engulfed and suffocated. Today,
0:11:52 > 0:11:55their entombed bodies still lie exactly where they died. The ash
0:11:55 > 0:12:01cloud swallowed Pompeii so quickly, the citizens wouldn't have known
0:12:01 > 0:12:04what hit them. But here in the ancient city of
0:12:04 > 0:12:10Herculaneum, 15 kilometres to the west, people would have seen the
0:12:10 > 0:12:14horror unfolding. The wind had blown the ash cloud to
0:12:14 > 0:12:18the south towards Pompeii, so from Herculaneum, they would have had a
0:12:18 > 0:12:23clear view of Vesuvius. It's hard to imagine what must have gone
0:12:23 > 0:12:28through their minds. Their mountain, which hadn't even been recognised
0:12:28 > 0:12:34as a volcano, was exploding into life. A huge black cloud filled the
0:12:34 > 0:12:42sky, and the ground was wracked by It must have seemed like the end of
0:12:42 > 0:12:49the world was coming. But unlike their neighbours in Pompeii, the
0:12:49 > 0:12:54people here had time to run for shelter. These homes and buildings
0:12:54 > 0:13:01were found abandoned. The people had fled, but that didn't mean
0:13:01 > 0:13:11they'd escaped. When archaeologists excavated these ancient chambers,
0:13:11 > 0:13:13
0:13:13 > 0:13:17they made a shocking discovery. So in each of these chambers were
0:13:17 > 0:13:22found 30 to 40 victims of the eruption. Are these real skeletons?
0:13:22 > 0:13:27These are casts, but they're just to the real exact copy of the
0:13:27 > 0:13:35victims as they were found. What's the story of these skeletons, then?
0:13:35 > 0:13:38At the beginning of the eruption, the town was shocked by several
0:13:38 > 0:13:43earthquakes. They thought these arcades could be a safe place, but
0:13:43 > 0:13:48actually, this was not a good place to be for the eruption. Sheltering
0:13:48 > 0:13:57here was no use because the earthquakes and the huge ash cloud
0:13:57 > 0:14:04filling the sky was just the first phase of the eruption. Then came
0:14:04 > 0:14:08the pyroclastic surge, a lethal mixture of heat and gas. It tore
0:14:08 > 0:14:13through these streets at 150 kilometres an hour, obliterating
0:14:13 > 0:14:18everything and everyone in its path. Many skulls were exploded due to
0:14:18 > 0:14:22the direct effect of the heat on their bones and also due to the
0:14:22 > 0:14:26over-pressure induced by the boiling brains. Boiling brains?!
0:14:26 > 0:14:31This skull looks as if it has been crushed, but you're saying it's
0:14:31 > 0:14:35actually exploded out because their brains have boiled? Yes. What a way
0:14:35 > 0:14:43to go. So when the surge comes through the city, there's nothing
0:14:43 > 0:14:47which could protect them. After such a devastating natural
0:14:47 > 0:14:52disaster, you'd think no-one would ever want to live here again, but
0:14:52 > 0:14:56where once stood a Roman settlement of 5,000 people, there now stands a
0:14:56 > 0:15:00modern town of 50,000, and the people that live around here today
0:15:00 > 0:15:10face the same threat as the citizens of Herculaneum because
0:15:10 > 0:15:13
0:15:13 > 0:15:18In 1906 an eruption claimed over 200 lives. And 28 people were
0:15:18 > 0:15:23killed when Vesuvius blasted ash and rock over cities. These
0:15:23 > 0:15:27eruptions were relatively minor. A bigger one would be devastating ai,
0:15:27 > 0:15:32lethal surge from a major eruption could easily travel 20 kilometres
0:15:32 > 0:15:39or more. And that means they could reach the city of Naples. Threat
0:15:39 > 0:15:45ngs the lives of over a million people. That's why today, very
0:15:45 > 0:15:52suesious -- Vesuvius is one of the most heavily Monday order volcano
0:15:53 > 0:15:57on the planet. Scientists use the most sophisticated technology to
0:15:57 > 0:16:01keep watch over the volcano 24 hours a day. State-of-the-art
0:16:01 > 0:16:04instruments positioned around the crater feed information back to the
0:16:04 > 0:16:14control centre. So the scientists can monitor the volcano's every
0:16:14 > 0:16:17
0:16:17 > 0:16:20move. There are different devices like this thermal camera like
0:16:20 > 0:16:24detects any change inside the crater, in terms of temperature.
0:16:24 > 0:16:30That's like hot gases and hot fluids rise together surface?
0:16:30 > 0:16:39There are gas monitoring system and the seismic stations. So underneath
0:16:39 > 0:16:45this station here there will be a seismometer will there, recording
0:16:45 > 0:16:49that activity. Yes. The temperature of the crater and composition of
0:16:49 > 0:16:56gases, the scientist will know when magma deep inside the kol vaino
0:16:56 > 0:17:02moves towards the surface, a keel indicator that an eruption is
0:17:02 > 0:17:08imminent. Only by merging data by all these instruments can we know
0:17:08 > 0:17:13about an evupgs. Could a big eruption like 79 AD happen again
0:17:13 > 0:17:20snfpblts yes, of course. Our Research instruments demonstrate
0:17:20 > 0:17:26there is a wide magma chamber, as wide as 400 square kilometres. So
0:17:26 > 0:17:31there is magma available for hundreds of large-scale eruptions
0:17:31 > 0:17:34like the Pompeii one. These high- tech instruments can help
0:17:34 > 0:17:39scientists predict when the next eruption might occur. But they
0:17:39 > 0:17:46can't stop it from happening. So the danger facing the people who
0:17:46 > 0:17:51live here today is as high now as it was in 79AD. The difference is
0:17:51 > 0:17:56today we think we understand this volcano, by combining modern
0:17:56 > 0:17:59scientific techniques with evidence of past eruptions like the one in
0:17:59 > 0:18:0379AD. Scientists know what this volcano is capable of and believe
0:18:03 > 0:18:07they can read its warning signs. That is only half the story.
0:18:07 > 0:18:12Because the question is - when those warnings come will the
0:18:12 > 0:18:15authorities down there be ready? Can we really evacuate all these
0:18:15 > 0:18:24people safely? That, perhaps more than the science, will be the
0:18:24 > 0:18:29really tricky part. Is there a plan, if it does happen? Do you think the
0:18:29 > 0:18:33authorities can react and evacuate people? Yeah, there's a plan. The
0:18:33 > 0:18:37assumption is that the eruption won't happen suddenly. There will
0:18:37 > 0:18:40be maybe two weeks notice, either from gas or earthquakes or tilts or
0:18:40 > 0:18:45something like. That the plan is that they're going to evacuate the
0:18:45 > 0:18:50red area. The red area is the area with the pyroclastic flows which we
0:18:50 > 0:18:54saw were so deadly. The trouble is that 600,000 people live in that
0:18:54 > 0:19:01red area. Wow! That's extraordinary. Just the physical, how do you get
0:19:01 > 0:19:06all those people out? If they have two weeks, the plan is to mobilise
0:19:06 > 0:19:1016,000 police and soldiers to get 80,000 people a day out on 80 ships,
0:19:10 > 0:19:1540 trains, 4,000 cars. Here's the thing, they might not have two
0:19:15 > 0:19:18weeks. They might have as little as 72 hours. I was going to say,
0:19:19 > 0:19:23that's a big assumption, we'll have two weeks and have it
0:19:23 > 0:19:28organisationed. The other thing is, they may have to evacuate far more.
0:19:28 > 0:19:33They might have to evacuate areas where the ash cloud is going. They
0:19:33 > 0:19:41don't want another Pompeii. The other thing is, the assumption of
0:19:41 > 0:19:44the size is that it's best an eruption smaller than AD79. But if
0:19:44 > 0:19:49it's going to be huge, all those numbers have to increase. They're
0:19:49 > 0:19:53not planning for the worst. They're planning for the best case scenario.
0:19:54 > 0:19:56At least Naples has a plan. That's true. There's other volcanoes
0:19:56 > 0:20:03around the planet with equally important threat, yet don't have
0:20:03 > 0:20:09such a plan in place. It's scary. It is, it is scary. It's not just
0:20:09 > 0:20:11in places like Naples. It's scary for the people who work here at the
0:20:12 > 0:20:17Hawaii Volcanoes National Park. 5,000 visitors a day come here.
0:20:17 > 0:20:21When you see that, don't you want to book your ticket? Jim Gale you
0:20:21 > 0:20:25have the unenviable task of making sure that people have access to
0:20:25 > 0:20:30this wonderful park, to these wonderful sites, but also being
0:20:30 > 0:20:34safe. Now you've got the HVO, the scientist perched over there,
0:20:34 > 0:20:38presumably you work together? Absolutely. They are part of the
0:20:38 > 0:20:43team. They provide the most up to date science in the current
0:20:43 > 0:20:47eruption. How do you measure what they're telling you in terms of how
0:20:47 > 0:20:51you then need to react as far as the public are concerned? The most
0:20:51 > 0:20:59important part is keeping the visitors safe. Yeah. Out of the
0:20:59 > 0:21:02dangerous gases or away from thing that's could cause harm or have an
0:21:02 > 0:21:06unpleasant vacation. If there's a shift in wind or something like
0:21:06 > 0:21:09that, that's why we needed to close the road over there, because the
0:21:09 > 0:21:13wind blows that direction and the gass are too much. There used to be
0:21:13 > 0:21:17a road that went all the way round the crater? That's right. You've
0:21:17 > 0:21:22closed that because it's the prevailing wind. Correct. So you're
0:21:22 > 0:21:27kind of constantly monitoring the various conditions around the park
0:21:27 > 0:21:35and reacting accordingly. Exactly. Has there ever been a time where
0:21:35 > 0:21:40you have had to say, close the park, nobody in here? For one day we had
0:21:40 > 0:21:44a forecast from the scientists that the plume was going to shift back.
0:21:44 > 0:21:47Right. We needed to close the park because we were so afraid. We
0:21:47 > 0:21:50didn't know what was going to happen. We neelded to protect the
0:21:50 > 0:21:54visitors. For that one day, we closed the park tone sure that
0:21:54 > 0:21:57visitors would not be in harm's way. What the scientists were telling
0:21:57 > 0:22:02you was that plume would come in this direction, basically flooding
0:22:02 > 0:22:05the whole area of the park? Right. Right now we're in good wind. We're
0:22:05 > 0:22:09up wind of the vent. But the weather was shifting and it was our
0:22:09 > 0:22:14first time that had ever happened, so we didn't know exactly what was
0:22:14 > 0:22:17going to happen. And I mean, what was the sort of outcome of that?
0:22:17 > 0:22:22Were people furious, did they understand what you were doing?
0:22:22 > 0:22:27Well, we learned a lot. What we learned was that there's always an
0:22:27 > 0:22:31open area of the park, noi, we can take people to a place that's open.
0:22:31 > 0:22:36But one of the key things you learned was that people changed
0:22:36 > 0:22:39their travel plans. They cancelled their airline reservations,
0:22:39 > 0:22:44cancelled their hotel. implications were not just for the
0:22:44 > 0:22:48park. You had a ripple effect on the whole island. Absolutely.
0:22:48 > 0:22:52Because the island presumably depends on the economics that you
0:22:52 > 0:22:57provide here. Right. Not an easy decision to make, then, but
0:22:57 > 0:23:00presumably you have to put safety first? Absolutely. That's the whole
0:23:00 > 0:23:04purpose is providing an approachable, visitor experience
0:23:04 > 0:23:09with viewing the lava, but not at the cost of someone's health or
0:23:09 > 0:23:12safety. I don't envy you your job, Jim. I certainly envy where you
0:23:12 > 0:23:18work. Thank you very much. It's been a pleasure working with you
0:23:18 > 0:23:22this week. Thank you. Now to Iceland. It's one of the most
0:23:22 > 0:23:27volcanically active countries on earth. We all remember that
0:23:27 > 0:23:32eruption of 2010, Eyjafallajokull, that caused chaos in all our lives.
0:23:32 > 0:23:35Actually as I learned when I was in Iceland, that's nowhere near the
0:23:35 > 0:23:45biggest volcano there. It's the next door neighbour that is really
0:23:45 > 0:23:49
0:23:49 > 0:23:59mountainous terrain has been shifting and changing for thousands
0:23:59 > 0:23:59
0:23:59 > 0:24:06of years. The scale of this landscape, it's just astonishing.
0:24:06 > 0:24:11There are huge ca vass that have opened up as the glacier sweeps
0:24:11 > 0:24:20down the side of this mountain. Of course, this isn't a mountain. This
0:24:20 > 0:24:24is a volcano. Lying beneath the ice the volcano is one of the largest
0:24:24 > 0:24:29and most active volcanoes in Iceland. When Eyjafallajokull
0:24:29 > 0:24:37erupted just a few miles from here in 2010, there were also
0:24:37 > 0:24:41suggestions that a big eruption here is now overdue. To find out
0:24:41 > 0:24:46whether that's true, we're leaving the helicopter behind and hitching
0:24:46 > 0:24:52a ride in specially adapted Jeeps to get us across the huge and
0:24:52 > 0:24:57treacherous ice cap. Why is it necessary to have such
0:24:57 > 0:25:07big tyres? Is it just to make you feel a bit more macho? A little bit
0:25:07 > 0:25:08
0:25:09 > 0:25:15like that! No! It's a vast ocean of ice and we drive for several miles
0:25:15 > 0:25:21without seeing a thing. Along the way, we're joined by a snow mobile.
0:25:21 > 0:25:31It's a dramatic entrance, but thankfully this is no Bond villain.
0:25:31 > 0:25:33
0:25:34 > 0:25:39It's one of Iceland's leading volcano onctions. -- volcanologists.
0:25:39 > 0:25:49He leads us to a rocky outcrop, the highest poipt for miles around. --
0:25:49 > 0:25:54point. We are actually at the edge of the rim. This is a depression
0:25:54 > 0:26:00that is formed when magma chamber is emptied. What we're looking at
0:26:00 > 0:26:06here is snow and ice covering that kind of classic volcano crater. And
0:26:06 > 0:26:12this stretches in which direction? If you look around here we see the
0:26:12 > 0:26:17edge of the rim. So all the high points? The high points here are at
0:26:17 > 0:26:23the edge of the rim, all the way around. I mean it's absolutely
0:26:23 > 0:26:32enormous. It's enormous, about ten kilometres diameter. How thick is
0:26:32 > 0:26:35the ice? About 750 metres. Wow! They're the huge craters found at
0:26:35 > 0:26:42the top of the very biggest volcanoes in the world. They're
0:26:42 > 0:26:51formed by what are known as super eruptions, and Katla's caldera was
0:26:51 > 0:26:58maid in that way. The explosions that created it, several thousand
0:26:58 > 0:27:08years ago, were 50 times bigger than Eyjafallajokull in 2010,
0:27:08 > 0:27:09
0:27:09 > 0:27:14depositing ash layers in Russia, some 2,000 miles away. Forchly, not
0:27:14 > 0:27:20every eruption is that bit. But they've seen plenty of activity in
0:27:20 > 0:27:25the last few hundred years. How active is this volcano? Well it has
0:27:25 > 0:27:31been erupting roughly once or twice every century. OK, so the last time
0:27:31 > 0:27:36it had a great eruption? It was in 1918. It was about, well, three
0:27:36 > 0:27:43times bigger than the Eyjafallajokull eruption. In 1918,
0:27:43 > 0:27:47heat from the eruption melted part of the glacial ice in the caldera.
0:27:47 > 0:27:54An enormous flood was unleashed ripping ice from the glacier and
0:27:54 > 0:27:58carrying them down towards the coast. That is almost a century ago.
0:27:58 > 0:28:04Yes. Does that mean it's kind of overdue? I mean, no, I wouldn't say
0:28:04 > 0:28:09that. Volcanoes aren't overdue. They change patterns on a regular
0:28:09 > 0:28:13basis or irregular basis actually. They are irregular and complex
0:28:14 > 0:28:23things. It might erupt in ten years or 50 years. It might erupt in a
0:28:24 > 0:28:25
0:28:25 > 0:28:29few weeks. OK, shall we get this job done then?! The length of time
0:28:29 > 0:28:35between eruptions here varies a lot. So the only way to forecast exactly
0:28:35 > 0:28:39when the next eruption might be is by carefully monitoring its
0:28:39 > 0:28:45behaviour. Bennie uses extremely sensitive GPS instruments and if
0:28:45 > 0:28:51the ground here moves by just a single centimetre in any direction,
0:28:51 > 0:28:57that movement will be recorded. It looks, to the uninitiated eye, that
0:28:57 > 0:29:02it's moving quite a lot. Yes, it is. It is moving quite a lot. What we
0:29:02 > 0:29:07are looking at now is volcanic unrest. That's a long-term
0:29:07 > 0:29:14indicator that something is, could potentially happen. It could
0:29:14 > 0:29:17potentially happen at short notice. But Bennie is used to seeing
0:29:17 > 0:29:22chaotic ground movements in this area. What he's really looking for
0:29:22 > 0:29:30is evidence that shows whether the pressure is building in the magma
0:29:30 > 0:29:37chamber, deep beneath our feet. How does magma accumulating, kilometres
0:29:37 > 0:29:47below us presumably, how does that affect a GPS instrument right up
0:29:47 > 0:29:52
0:29:52 > 0:29:57volcano, and it's - there is magma coming into the magma chamber. It
0:29:57 > 0:30:02increases the pressure in the magma chamber, so you basically -
0:30:02 > 0:30:06increasing it in size. Right. So you... It's like blowing up a
0:30:07 > 0:30:13balloon, so you see it on the surface. You see an uplift and
0:30:13 > 0:30:18away... Oh. So Benny won't issue any warnings until he sees clear
0:30:18 > 0:30:24movement up and away from the magma chamber over a period of days or
0:30:24 > 0:30:30weeks. Only that would suggest that Katla is building up to a really
0:30:30 > 0:30:38big eruption. In the meantime, Katla continues to rumble away, and
0:30:38 > 0:30:43just last year, a small episode of geothermal activity was registered
0:30:43 > 0:30:48beneath the icecap. Now that geothermal activity of 2011 heated
0:30:48 > 0:30:53up the ice and caused a flood of water too come pouring off the
0:30:53 > 0:30:58volcano and down this river valley, taking out the bridge and causing
0:30:58 > 0:31:05mass devastation as it made its way to the sea. The flood was a smaller
0:31:05 > 0:31:08version of the deluge in 1918. It's a reminder that even between big
0:31:08 > 0:31:16eruptions, Katla can still pose serious problems for those living
0:31:16 > 0:31:24nearby. That makes it vital that we continue to monitor this slumbering
0:31:24 > 0:31:28It is an incredible country, Iceland, and it is incredible,
0:31:28 > 0:31:32really, how the people there kind of cope with this volatile home
0:31:32 > 0:31:36that they have chosen to live in. I have presented a one-hour special
0:31:36 > 0:31:39on Iceland and its volcanoes which will be going out on BBC Two a
0:31:39 > 0:31:43little bit later in the year - we think in the autumn, so keep your
0:31:43 > 0:31:48eye out for that but it does seem to me, Ian, that this predicting
0:31:48 > 0:31:50what a volcano is going to do and then telling people what your
0:31:51 > 0:31:54prediction is is sort of fraught with problems and controversy
0:31:54 > 0:31:59really. Yeah, that's the real tricky business. If you see the
0:31:59 > 0:32:02signals and raise the alarm and nothing happens, then, there is all
0:32:02 > 0:32:05sorts of disruption and panic. On the other hand, if you don't see
0:32:05 > 0:32:10the signals and don't raise the alarm, then you get it in the neck
0:32:10 > 0:32:14because there is a disaster then too. That's one of the reasons why
0:32:14 > 0:32:18volcanologists have moved away from being predictive and gone for
0:32:18 > 0:32:23forecasting, in other words, saying something about the likelihood of
0:32:23 > 0:32:27an eruption, snai, days or weeks in large part so that people can be
0:32:27 > 0:32:34prepared... Make their own decisions, feel informed about
0:32:34 > 0:32:37making their own decisions. All of this week, we have had some very
0:32:37 > 0:32:40up-to-the-minute information from the Smithsonian to tell us which
0:32:40 > 0:32:44volcanos have had alerts, basically. They're all active and all
0:32:44 > 0:32:48volcanoes people should be keeping an eye on. Here they are this is
0:32:48 > 0:32:52the latest - all the volcanoes that have alerts on in the last 24 hours.
0:32:52 > 0:32:58Many of you have e-mailed to say, why are you missing out New
0:32:58 > 0:33:04Zealand? They have volcanoes. They have but none with the alerts on.
0:33:04 > 0:33:08On the edge of the map. It's not being ignored. We promise. One in
0:33:08 > 0:33:16Ecuador - that is - if we can have a look at the webcam, we have some
0:33:17 > 0:33:20mild plume activity from - there it It's hard to see what is behind
0:33:20 > 0:33:26that cloud, but we know there has been some plume activity coming up.
0:33:26 > 0:33:30The problem with that is it's so close to Quito, the capital of
0:33:30 > 0:33:33Ecuador. Even a moderate eruption from this volcano could have a
0:33:33 > 0:33:40devastating effect, so a huge one to watch over the coming days.
0:33:40 > 0:33:44other one, again, we looked at over the coming week is one in Japan you
0:33:44 > 0:33:48know quite well. Yes, this is just on this isle in southern Japan. If
0:33:48 > 0:33:52we can have a look at the webcam, I wonder what the latest is on that.
0:33:52 > 0:33:57That is going to tell us a lot, isn't it?! That is the problem. You
0:33:57 > 0:34:02can keep an eye on these by going to our website. I have to say also,
0:34:02 > 0:34:09it's night-time in Japan. If you go there, it will be black. In 2005,
0:34:09 > 0:34:14to give you an idea, this is Kagashima, one million population
0:34:14 > 0:34:18city. This is one striking distance of big pyroclastic flows. I went to
0:34:18 > 0:34:22the community and went into the school to see the kind of protocols
0:34:22 > 0:34:24and practisings they have. The schoolkids - these are primary
0:34:24 > 0:34:28schoolkids - every Friday have a drill. They rush out of the
0:34:28 > 0:34:33classroom. They get their protective hard hats for the ash.
0:34:33 > 0:34:36They get the gas masks for the ash. They run down the stairs and
0:34:36 > 0:34:40assemble in the playground outside where they're checked out. This is
0:34:40 > 0:34:43my favourite - look at these. Every Friday they have - you can't see
0:34:43 > 0:34:47this, but just above the school is the volcano. The point is in many
0:34:48 > 0:34:51of these communities around the world, although these people are
0:34:52 > 0:34:57drilled for volcanoes in their midst - this is what people in the
0:34:57 > 0:35:02UK forget about. That's it. We're not living in a volcanic landscape,
0:35:02 > 0:35:06so we tend to perhaps build them up more than other people do, which
0:35:06 > 0:35:11brings us neatly on to other questions you have sent in. We have
0:35:11 > 0:35:15a fantastic amount. The first one from Alex in Rhyl. He's going to
0:35:15 > 0:35:20Vesuvius this October with his school. He wonders are there any
0:35:20 > 0:35:23laws on taking samples of volcanoic rock from Vesuvius back home to the
0:35:23 > 0:35:26UK? That's a great question. I think there are. Many of these
0:35:26 > 0:35:31volcanoes are protected sites. He'll need to check, but I don't
0:35:31 > 0:35:34think you can. When I was there, I didn't take any because I was
0:35:34 > 0:35:38certainly worried. Here you're definitely not allowed to. You're
0:35:38 > 0:35:43not because there is a goddess called Madam Pele, who lives inside
0:35:43 > 0:35:48the volcano. It is deemed hugely bad luck and bad form to take a
0:35:48 > 0:35:53rock from here. In fact, the Post Office in Hilo here receives
0:35:53 > 0:35:59hundreds of packages of lava being returned because they have had bad
0:35:59 > 0:36:04luck and thought, I have to quickly send it back to the goddess. In
0:36:04 > 0:36:09Kent, one viewer asks what the people of Pompeii thought it was if
0:36:09 > 0:36:14they didn't think it was a volcano. The Greeks knew it, but it hadn't
0:36:14 > 0:36:19erupted for centuries, so for the Romans, it was just a mountain.
0:36:19 > 0:36:23Caroline Lomas wants to know - this is a very good question - can one
0:36:23 > 0:36:27volcanoic eruption trigger a chain reaction? I know this is something
0:36:27 > 0:36:32in Iceland people were worried - Eyjafjallajokull could trigger
0:36:32 > 0:36:37Katla to go all. It turns off they have separate Magma chambers, but
0:36:37 > 0:36:43could they? There could be stress between them, and also earthquakes
0:36:43 > 0:36:50between them. One that is nice is between Kilauea and Mauna Loa here.
0:36:50 > 0:36:55When Mauna Loa kicks off, Kilauea goes quiet. When Mauna Loa kicks
0:36:55 > 0:37:01off, Kilauea goes quiet. John Howard wants to know are there any
0:37:01 > 0:37:08active under-sea volcanos? Lot and lots, probably the most common, but
0:37:08 > 0:37:14we don't issue alerts. One from Cardiff: "If Magma is being
0:37:14 > 0:37:20released and forming new land, does that mean..." Shrinking? No,
0:37:20 > 0:37:24because that builds new land. It I gets taken back into the mud. It's
0:37:24 > 0:37:32a beautiful recycling system. you, as I say, for all of you who
0:37:32 > 0:37:37sent in your questions. I want to make a quick mention, Jack, Dara
0:37:37 > 0:37:41and others have said they want to be volcanologists and want to know
0:37:41 > 0:37:44how. That is good point. This week we have talked a lot about this
0:37:44 > 0:37:49high-tech stuff, but what has been a joy to me is where you see the
0:37:49 > 0:37:52films of the people who study them and also the lengths they go to get
0:37:52 > 0:37:57their data, and one that exemplifys that passion and commitment for me
0:37:57 > 0:38:07more than any other is Clive Oppenheimer, and this week, Clive
0:38:07 > 0:38:18
0:38:18 > 0:38:21I'm interested in volcanoes, why they work, why they erupt in a
0:38:21 > 0:38:26particular way. If we want to be able to predict eruptions, that's
0:38:26 > 0:38:31obviously one of the key goals of volcanology. We need towns how they
0:38:31 > 0:38:38work, so we need to find laboratory volcanoes where we can make very
0:38:38 > 0:38:42detailed measurements. Mount Aravus in Antarctica is the world's most
0:38:42 > 0:38:48southern active volcano. It is over one million years old. Every
0:38:48 > 0:38:51December I make the epic journey to this mountain with a team of a
0:38:51 > 0:38:55dozen students and scientists to live and work for a month. The main
0:38:55 > 0:39:01reason I go there is to measure the gas emissions from the lava lake.
0:39:01 > 0:39:06They're really like messages from the earth's interior. It is a big
0:39:06 > 0:39:12project to go there. You need a lot of time, but the scientific rewards
0:39:12 > 0:39:22are just phenomenal. I have been coming here to the very edge of the
0:39:22 > 0:39:22
0:39:22 > 0:39:28world for the past nine years. We fly to New Zealand, then on to Ross
0:39:28 > 0:39:37Island where we pick up provisions, then finally take a helicopter the
0:39:37 > 0:39:44last hop over Arabus. We go to an aclimatisation camp, called the
0:39:44 > 0:39:47Fang Glacier. We call it Fang Camp. Going to high Ault altitude, you
0:39:47 > 0:39:52suddenly realise you're in Antarctica, and the views are
0:39:52 > 0:39:56spectacular. The camp here is pretty basic with just a few tents
0:39:56 > 0:40:06and a bucket. We try to aclimatise for at least a couple of nights in
0:40:06 > 0:40:08
0:40:08 > 0:40:12Fang. We travel by Skidoo to our main field camp. This is my home
0:40:12 > 0:40:18for a month every year. It's a truly extraordinary place, and it's
0:40:18 > 0:40:23a bit like landing on Mars. We set up camp next to two permanent huts
0:40:23 > 0:40:27just an hour's walk from the summit of the volcano - the typical
0:40:27 > 0:40:32temperature in the camp would be about minus 30 Celsius. If the wind
0:40:32 > 0:40:37is up, even if it's just a few knots, then you really start to
0:40:37 > 0:40:41feel it. And working up at the crater - particularly if you've got
0:40:41 > 0:40:49to take your gloves off to fiddle with a screwdriver or something -
0:40:49 > 0:40:56you lose fingers in seconds. The cold and altitude have also led to
0:40:56 > 0:40:59two helicopter crashes over Erebus, but luckily, everyone survived.
0:40:59 > 0:41:09It's just a reminder of the dangers of being up in that part of the
0:41:09 > 0:41:13world. We do still sleep in tents. It's our one sort of nod to the
0:41:13 > 0:41:17heroic era that you have Scott tents, and they're not black-out
0:41:17 > 0:41:22tents, so it's a little bit difficult actually coping with the
0:41:22 > 0:41:26daylight that you have 24 hours a day. Life is harsh here, but
0:41:26 > 0:41:31studying the volcano makes it all worthwhile. Depending on the
0:41:31 > 0:41:36weather, we try to get up to the crater rim every day where we
0:41:36 > 0:41:40monitor its activity. The crater is half a kilometre across, and the
0:41:40 > 0:41:46lava lake here at Erebus is one of only four major lava lakes in the
0:41:46 > 0:41:51world. I am here to measure the gases in the volcanoic plume.
0:41:51 > 0:41:56Measures the composition and flux of gases allows me to understand
0:41:56 > 0:42:06why the volcano works and why it has a lava lake.
0:42:06 > 0:42:10My favourite device on Erebus is my FTR, my infrared spectrometre. It
0:42:11 > 0:42:13measures anything that's coming out of the volcano. There are seven
0:42:13 > 0:42:17different gas species we can measure. The nice thing is we can
0:42:17 > 0:42:21measure those every second with very, very high accuracy. That's
0:42:21 > 0:42:26great for following subtle changes in the behaviour of the volcano and
0:42:26 > 0:42:30very rapid changes. And the gas emissions themselves are one of the
0:42:30 > 0:42:36best messengers to tell us where is magma in the crust? How deep is it?
0:42:36 > 0:42:41Is it full of gas or not? Is it on the rise? Is the volcano gearing
0:42:41 > 0:42:47towards a different kind of eruption?
0:42:47 > 0:42:51The ice caves are one of the most stunning features on Erebus. And
0:42:51 > 0:42:57they're a bit of a puzzle actually as to why they're there in the
0:42:57 > 0:43:04first place. They're connected with the heat that's being lost from the
0:43:04 > 0:43:07volcano and also from gases. We know that some of the caves are
0:43:07 > 0:43:11very rich in carbon dioxide in their atmospheres, so we think
0:43:11 > 0:43:14possibly they're connected also with the magma plumbing system of
0:43:14 > 0:43:22the volcano. So we have an active research programme trying to
0:43:23 > 0:43:25understand their formation and origins. A very exciting aspect of
0:43:25 > 0:43:29Erebus's behaviour is that it explodes from time to time, unlike
0:43:29 > 0:43:34other lava lakes, in fact. We use the camera to observe the volcano
0:43:34 > 0:43:38when we're not up on the rim, of course, but also to capture the
0:43:38 > 0:43:48explosions. Some of them are very dramatic. All the lava in the lake
0:43:48 > 0:43:51
0:43:51 > 0:43:59is expelled. Sometimes they almost Each year, we look for new lava
0:43:59 > 0:44:03bombs to sample so that we can analyse them back in the lab. There
0:44:03 > 0:44:08is still a huge amount we have to learn about Erebus, but what we're
0:44:08 > 0:44:12finding out here will help us to understand other volcanoes across
0:44:12 > 0:44:18the world. One of the things that makes Erebus a fantastic place to
0:44:18 > 0:44:24work is it's very cold, and it's very dry. Erebus is a great natural
0:44:24 > 0:44:29laboratory to study how a volcano works, and that has all sorts of
0:44:29 > 0:44:34generic lessons for understanding volcanoes worldwide. I think the
0:44:34 > 0:44:37measures we have made of gas emissions at Erebus rivals anything
0:44:37 > 0:44:40I have seen for volcanoes around the world. We've got really
0:44:40 > 0:44:44detailed data and have been going there year after year. We measure
0:44:44 > 0:44:49gas emissions every second, and that's really enabled us to piece
0:44:49 > 0:44:55together lot of the detail about how the volcano is plumbed into its
0:44:55 > 0:44:59network of magma bodies and feeder pipes below the surface. It's an
0:44:59 > 0:45:07exceptional place to live and - I mean, just amazing privilege to get
0:45:07 > 0:45:16to work there and to get to go back There you are, how would you like
0:45:16 > 0:45:21to go down toant arbgta to study volcanoes. They have one of only
0:45:21 > 0:45:26four permanent lava lakes in the world. One of the others is here.
0:45:26 > 0:45:32Dave is with me now. Thank you for joining us today. You have been
0:45:32 > 0:45:35spending the last months and weeks actually mapping this lava lake,
0:45:35 > 0:45:38using this extraordinary piece of kit. Can you just talk me through
0:45:38 > 0:45:44this? I've never seen anything like it. This is actually called a
0:45:44 > 0:45:52ground based lidar system. It's a laser beam mapping system that
0:45:52 > 0:45:56allows us to do high precision mapping at centimetre scale at long
0:45:56 > 0:45:59distances. It allows us to actually map in three dimensions different
0:45:59 > 0:46:04parts of the volcano. Why is that important? Why is it important to
0:46:04 > 0:46:08have that sense of distance? Surely you need to get up close to really
0:46:08 > 0:46:12understand what a volcano is doing. What's really important is we need
0:46:12 > 0:46:16to get close, but nine times out of ten we can't get there. It's too
0:46:16 > 0:46:21dangerous, the gases and heat and some of the other people have said
0:46:21 > 0:46:23it's important to have a stand-off system that allows to us get
0:46:23 > 0:46:28precision information at long ranges. These systems allow us to
0:46:28 > 0:46:31do that. They allow us to map in 360 degrees, at very high precision,
0:46:31 > 0:46:37without putting people in harm's way, but coming up with the science
0:46:37 > 0:46:43information that we really need. Well, I'm going to have a look at
0:46:43 > 0:46:48the results of your work with this extraordinary machine with Dave's
0:46:48 > 0:46:54colleague, Professor Steve Anderson from the university of northern
0:46:54 > 0:46:57Colorado. Good morning. Good morning. An impressive piece of kit.
0:46:57 > 0:47:00Presumably giving you impressive results. Before we have a look at
0:47:00 > 0:47:05what you've been able to produce over the last few weekends, let's
0:47:05 > 0:47:10have a look at the view of the crater that we are more used to
0:47:10 > 0:47:15seeing. It's a pretty good view. is. But I suppose from a scientific
0:47:15 > 0:47:19point of view, a little vague. It tells you some things but not quite
0:47:19 > 0:47:24enough to be analytical. Right. Beautiful views, as I say, so how
0:47:24 > 0:47:28does the view that you have managed to produce differ from that? Since
0:47:28 > 0:47:34the crater opened about four years ago, one of the biggest hazards
0:47:34 > 0:47:40they've had to contend with here are rock falls from that crater
0:47:41 > 0:47:42wall landing in the lava lake and producing impressive explosions.
0:47:42 > 0:47:48producing impressive explosions. have footage of those rock falls.
0:47:48 > 0:47:53It is dramatic. Let's have a look. That is one of the biggest risks of
0:47:53 > 0:47:58this particular crater, It's true. So from your map that you've
0:47:58 > 0:48:02produced, which I think we can have a look at, what has that told you?
0:48:02 > 0:48:07If you can talk us through it. It's a bit confusing. This is the crater
0:48:07 > 0:48:11here. We took this image back in February. Again, a couple of days
0:48:11 > 0:48:15ago. This image from February shows the crater walls here. As it pans
0:48:15 > 0:48:19around, you'll be able to see into the crater. This is the lava lake
0:48:19 > 0:48:23here. It's down here. What we've noticed from February to today is
0:48:23 > 0:48:28that the level of the lava lake has gone up about 20 metres. Wow.
0:48:28 > 0:48:31that parts of crater wall, especially down here, have widened
0:48:31 > 0:48:37substantially as rocks have fallen in. We're trying to get an idea of
0:48:37 > 0:48:41how this crater works so that the park service and HVO can use the
0:48:41 > 0:48:44information to make informed hazard predictions. Is there anything
0:48:44 > 0:48:48you've noticed, I mean, you say that the lake has risen 20 metres,
0:48:48 > 0:48:51are there any other features that have alerted you? When we first saw
0:48:51 > 0:48:57this image, the thing that really jumps out is something you'll see
0:48:57 > 0:49:01in a second, this rock ledge right here. As it turns, you'll see it
0:49:01 > 0:49:04overhangs by about 30 metres. Now when you look at that, it's like,
0:49:04 > 0:49:10well, that's potentially a problem. On the other hand, it could remain
0:49:10 > 0:49:15stable for a long period of time. It could break off in a piecemeal
0:49:15 > 0:49:18fashion. We don't know yet. The research is based on trying to come
0:49:18 > 0:49:22to a better understanding of what's going on in there. Presumably this
0:49:22 > 0:49:26very accurate mapping, it is extraordinarily detailed. It is.
0:49:26 > 0:49:31Literally being able to pick out areas of rock, it is giving you and
0:49:31 > 0:49:35the people here a much better understanding of that crater.
0:49:35 > 0:49:42when you put these detailed views in the context of the history that
0:49:42 > 0:49:46the field jeeologist -- geologist accomplishes, it allows for more
0:49:46 > 0:49:50informed predictions that the USGS and park service will put out. We
0:49:50 > 0:49:54try to provide some information and science and ask and answer
0:49:54 > 0:49:58questions that could help. Thank you very much for joining us today,
0:49:58 > 0:50:02Stevement Thanks. The more we study volcanoes, the more we know about
0:50:02 > 0:50:07them. The one thing we definitely know is that if they choose to
0:50:07 > 0:50:13erupt, there is nothing we can do to stop them. How big can those
0:50:13 > 0:50:19eruptions be? Ed Byrne went to investigate.
0:50:19 > 0:50:25The bright sun was extinguished and the stars did wonder darkly in the
0:50:25 > 0:50:31eternal space. The icy earth swung blind and blackening in the
0:50:31 > 0:50:34moonless air. Morn came and went and came and brought no day. And
0:50:34 > 0:50:40men forgot their passions and the dread of this their desolation and
0:50:40 > 0:50:48all hearts were chilled into a selfish prayer for light.
0:50:48 > 0:50:53Cheerery stuff. Lord Byron wrote those words in July 1816, inspired
0:50:53 > 0:50:57by the year without a summer. What he didn't realise was the reason
0:50:57 > 0:51:04that the weather was so bad that year was because the year previous
0:51:05 > 0:51:08to that mount Tambora erupted off the coast of Indonesia, the largest
0:51:08 > 0:51:11volcanic eruption since records began. Which begs the question -
0:51:12 > 0:51:18how does a volcano erupting thousands of miles away have such a
0:51:18 > 0:51:23marked effect on the weather in Europe? It's all about the way
0:51:23 > 0:51:29volcanic ash plumes spread through the atmosphere. Dr Jeremy Philips
0:51:29 > 0:51:32specialises in ash plumes and is on hand to explain. To represent the
0:51:32 > 0:51:38earth's atmosphere, he's filled a tank with salt water. Dense water
0:51:38 > 0:51:44is at the bottom and less dense at the top. What you can see is a
0:51:44 > 0:51:47plume source. That's going to represent a volcano erupting. The
0:51:47 > 0:51:53plume rises up. The mixture then finds a level in the tank where
0:51:53 > 0:51:57it's the same density as the fluid in the tank. Then it can't rise any
0:51:57 > 0:52:02higher and it spreads across the tank. This is essentially what
0:52:02 > 0:52:07happens with volcanic plumes in the earth's atmosphere. Typically this
0:52:07 > 0:52:13level is somewhere between 15 and 25 kilometres high? The atmosphere.
0:52:13 > 0:52:17The density of the lower Air Forces the plume up and then it spreads
0:52:17 > 0:52:23out. Exactly. You can see these large clouds can spread until they
0:52:23 > 0:52:27circle the whole globe. When Iceland's Eyjafallajokull volcano
0:52:27 > 0:52:33erupted in 2010 the resulting ash plume covered most of northern
0:52:33 > 0:52:36Europe. By xar son the eruption of mount Tamboro was a thousand times
0:52:36 > 0:52:42bigger. Its ash engulfed the entire world. It became known as the year
0:52:42 > 0:52:46without a summer. The ash blocked the sun's rays causing climatic
0:52:46 > 0:52:53extremes that brought famine and death to tens of thousands across
0:52:53 > 0:52:58the globe. Here's what's left of Tambora today, a gigantic crater
0:52:58 > 0:53:03three miles across. There are other volcanoes which make even this look
0:53:03 > 0:53:08like small fry. This is yellow stone National Park
0:53:08 > 0:53:15in America and it's the site of a so-called super volcano. Incredibly
0:53:15 > 0:53:21the entire park sits inside a giant super volcanic crater or caldera.
0:53:21 > 0:53:25It's more than 30 miles wide and it last erupted over 600,000 years ago.
0:53:25 > 0:53:29Scientists think there are at least 50 super volcanoes on the planet.
0:53:29 > 0:53:34None have gone off for at least 26,000 years. It's difficult to
0:53:35 > 0:53:38imagine just how immense these eruptions must be. Dr Jennie
0:53:38 > 0:53:42Barclay, from the University of East Anglia, has explosive
0:53:42 > 0:53:52experiments to give me an idea. The first involves a film canister,
0:53:52 > 0:53:53
0:53:53 > 0:53:57milk, food dye and alka seltzer. That's pretty good. I hope that
0:53:57 > 0:54:07wasn't supposed to be a super volcano. No. This is one we would
0:54:07 > 0:54:10
0:54:10 > 0:54:15call VEI one. VEI is volcanic explosive index. This is a little
0:54:15 > 0:54:20explosion, quite small compared to a super volcano. It goes up to
0:54:20 > 0:54:25eight, eight being a supervolcano then. That's right. Here we have a
0:54:25 > 0:54:30bin. What we've done is we've filled the bin full of water.
0:54:30 > 0:54:35That's some of our magma. We will put coloured balls in to be broken
0:54:35 > 0:54:39up magma coming from our explosion. We're using this contraption?
0:54:39 > 0:54:47are indeed using this splendidly made contraption, which basically
0:54:47 > 0:54:57allows to us put a bit of lick wit -- liquid nitrogen in. Yes! We need
0:54:57 > 0:54:57
0:54:57 > 0:55:01to put our safety gear on. Righto. I like that I had to take off my
0:55:01 > 0:55:05glasses and put only slightly nerdier glasses on. You're part of
0:55:05 > 0:55:09the gang now. So this will turn into a gas and pressurise this,
0:55:09 > 0:55:12causing an explosion to drive up and give us a sense of the
0:55:12 > 0:55:22difference in size between these two types of eruption. It gives me
0:55:22 > 0:55:25
0:55:25 > 0:55:29a chance to play with like wid nitrogen -- liquid nitrogen.
0:55:29 > 0:55:39That was beautiful. That was a beautiful and colourful portrayal
0:55:39 > 0:55:39
0:55:39 > 0:55:46of a global catastrophe. When mount Tambora erufpt today threw out 50
0:55:46 > 0:55:51cubic kilometres of material. A super eruption could move a
0:55:51 > 0:55:56thousand cubic kilometres. That could bring a volcanic winter which
0:55:56 > 0:56:00could last years, if not decades and if we're really unlucky, plunge
0:56:00 > 0:56:04earth into a new Ice Age. What are the odds of this eruption? The odds
0:56:04 > 0:56:08typically go over hundreds of thousands or millions of years. So
0:56:08 > 0:56:12there will be another super eruption, but the likelihood, the
0:56:12 > 0:56:20chance of it happening over our lifetime and our children's
0:56:20 > 0:56:24lifetime is vanishingly small. It's a lfl film, but for me, I know
0:56:24 > 0:56:29this will get the tweets and e- mails going, I don't think we
0:56:29 > 0:56:33should get toad fixated on super volcanos. They happen so rarely.
0:56:33 > 0:56:39The thing we've seen this week is that active volcanoes are scattered
0:56:39 > 0:56:43across the planet in. Many of them are right besides huge population
0:56:44 > 0:56:49centres. We should take the science we've demonstrated this week and
0:56:49 > 0:56:56apply it around the world to save lives. Well you can still get your
0:56:56 > 0:57:01questions in. Jon Blundy is standing by. Bbc.co.uk/ volcanolive.
0:57:01 > 0:57:06For us we've come to the end of our time here in Hawaii. Time enough to
0:57:06 > 0:57:11thank the scientists here. And of course the staff at the Hawaii
0:57:11 > 0:57:14Volcanoes National Park who made this possible. And Madam Pele for
0:57:14 > 0:57:20giving us such a beautiful final day and we need to thank you. Thank
0:57:20 > 0:57:26you for all your questions, tweets and your contributions. It has been
0:57:26 > 0:57:32a really wonderful week. And we would just like to leave you with
0:57:32 > 0:57:37shots of Hawaii in all her glorious volcanic splendor, because when she