Climb with volcano experts to the summit of Nyiragongo, a highly active volcano in the Democratic Republic of the Congo. Twice in recent memory it has erupted, devastating Goma, a neighboring city of 1 million people. To investigate when it might erupt next, scientists climb into its crater toward a bubbling lava lake to deploy sensors and monitor the volcano’s activity. (Premiered October 10, 2018)
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Volcano on Fire
PBS Airdate: October 10, 2018
NARRATOR: In the heart of Africa are two of the world's most dangerous volcanoes. Within their craters, molten lava steams and boils. Over centuries, these volcanoes have erupted many times, but when will they erupt again? It's a crucial question, but no one knows the answer, because these are among the least-studied volcanoes in the world.
Now, an international team of scientists is investigating these giants. Their goal? To predict future eruptions and save lives.
BENOÎT SMETS (Royal Museum for Central Africa): Everything we do to understand these volcanoes is very important to avoid another disaster.
NARRATOR: They're heading to the volcano known as Nyiragongo, which towers over a rapidly growing city of a million people. An eruption in 2002 caused death and destruction.
CALEB KABANDA (Eruption Eyewitness): I would see the lava flowing and breaking all houses. You could hear the noise.
NARRATOR: To penetrate the volcanoes secrets, the scientific team descends into the crater itself. It's treacherous…
CHRIS JACKSON (Imperial College London): Everything's moving. Nothing is stable.
NARRATOR: …but with lives in the balance, the stakes could not be higher.
ALDO KANE (Safety Advisor): Oh, man, look at these rocks…just precariously balanced.
NARRATOR: Volcano on Fire, right now, on NOVA.
Deep in central Africa is one of the most spectacular, active and dangerous volcanoes on earth.
KAYLA IACOVINO (Arizona State University): That's terrifying. There's literally nothing like this in the world.
NARRATOR: This volcano, named Nyiragongo, threatens almost a million people in this region. Twice in recent memory, it has devastated the city of Goma.
NEWS REPORT (BBC NEWS 2002 CLIP): The red river keeps flowing, pouring out of the volcano and down towards Goma.
NARRATOR: Violent conflict in this region has often made it too dangerous to mount any large scientific expeditions, but a temporary peace opens the door for a ground-breaking investigation, because this giant is one of the least understood volcanoes in the world, both threatening and life-giving.
GOMA RESIDENT: (Translated from Congolese Swahili) The volcano? We say it has two faces: it kills and it gives life.
NARRATOR: A team of scientists will spend a week on Nyiragongo, the volcano that towers over Goma. Their goal is to find ways to predict when this volcano will next erupt.
KAYLA IACOVINO: A huge spike in the amount of sulfur dioxide, that could be something that happens before an eruption.
NARRATOR: Their search for answers will take them deep inside the crater…
CHRIS JACKSON: I've just come over the edge.
NARRATOR: …and into great danger.
ALDO KANE: If any of this rock goes, here, that's it for both of us.
NARRATOR: Now, the team is on its way to the 11,400-foot-high Nyiragongo. It lies on the Democratic Republic of Congo's eastern border with Rwanda. Its steep cone, created by successive eruptions over centuries, rises over a mile above Goma and the surrounding landscape. Forecasting eruptions is difficult and uncertain, even for well-studied volcanoes, but it can save lives by giving people time to get out of harm's way.
ALDO KANE: Twenty-three, twenty-four, twenty-five …
NARRATOR: To achieve that, the scientists have brought an array of equipment, to investigate this volcano in many different ways.
BENOÎT SMETS: Just take care that the men take the heavy bags.
NARRATOR: Leading the science team is Belgian volcanologist Benoît Smets.
BENOÎT SMETS: Studying Nyiragongo is always very important for me, because this volcano is very dangerous. It threaten a lot of people. Everything we do to understand this volcano is very important to avoid another disaster, like in 2002.
NARRATOR: Joining him are scientists from the local volcano observatory who want to install instruments on the crater rim. JOSUÉ Subira has studied this volcano for several years and knows firsthand how difficult the climb will be.
BENOÎT SMETS: (Translated from French) Well, how do you feel?
JOSUÉ SUBIRA (Goma Volcano Observatory): (Translated from French) Really bad.
BENOÎT SMETS: (Translated from French) Why do you feel bad? We're about to climb Nyiragongo.
JOSUÉ SUBIRA: (Translated from French) Yes, but it's stressful.
BENOÎT SMETS: (Translated from French) Why?
JOSUÉ SUBIRA: (Translated from French) Climbing it's really not easy.
JEFFREY JOHNSON (Boise State University): Actually, that's the one I'm worried about, because I don't want someone to drop it.
NARRATOR: American geologists, Jeff Johnson and Kayla Iacovino are worried about damage to the instruments they brought to help identify warnings of an eruption.
ALDO KANE: No, the sun's out down here. Did you have a good night last night?
NARRATOR: Former Royal Marine Aldo Kane is in charge of getting everyone and everything to the top of the volcano.
ALDO KANE: We've got science kit, expedition kit, rigging kit, food, water: nearly four tons of kit that's going up the hill today.
NARRATOR: Nyiragongo's crater rim is six-and-a-half-thousand feet above the jungle and only accessible on foot. It takes six hours for the team to reach its steep upper slopes. The weather's closed in. It's cold, but their reward is a view of one of Earth's great natural wonders.
JEFF JOHNSON: Oh, my god. That is so incredible.
KAYLA IACOVINO: There's literally nothing like this in the world.
CHRIS JACKSON: There's six permanent lava lakes on Earth. You are standing looking into one of those six.
BENOÎT SMETS: Of those six lava lakes, they are all babies compared to this site. All other global lava lakes could fit into this lava lake with tons of room left over. This lava lake is enormous.
KAYLA IACOVINO: The sheer size of it, I think, is just hard to fathom.
NARRATOR: The crater is almost a mile in diameter. Inside is a permanent cauldron of molten rock, and it constantly churns at almost 2,000 degrees Fahrenheit.
CHRIS JACKSON: It's ferocious, it feels very alive. And even when we're silent, there's that constant roar. It just doesn't let up at all.
NARRATOR: British geologist Chris Jackson has studied volcanic landscapes across the world. For him, volcano prediction is a scientific and humanitarian challenge. Yesterday, he travelled in through the city that lies at the foot of the volcano.
CHRIS JACKSON: It's amazing to think that there's such a threat posed by that volcano, yet, because of that volcano, you can build houses and some sort of infrastructure.
NARRATOR: Goma, a city of almost a million people, is growing and modernizing rapidly. Houses are going up everywhere with foundations made from volcanic lava.
CHRIS JACKSON: This is incredibly exciting to be joining the expedition like this, to do cutting-edge critical science for the people living in the shadow of this giant volcano.
NARRATOR: In the outskirts of the city, the volcano is virtually a next-door neighbor.
CHRIS JACKSON: This place may look like a building site, but it's a building site sitting directly on top of this, this lava, which was erupted only 15 years ago from the volcano of Nyiragongo. For the people who live in the city of Goma, this is just a disaster waiting to happen.
NARRATOR: A disaster that has happened many times before.
NEWS REPORT (BBC NEWS 2002 CLIP): Daylight, and some of the first pictures reveal a black blanket of lava covering entire neighborhoods.
NARRATOR: When Nyiragongo erupted in 2002, lava flows split the city in three, destroying many homes and causing about a hundred deaths, as people fled for their lives.
NEWS REPORT (BBC NEWS 2002 CLIP): The red river keeps flowing, pouring out of the volcano and down towards Goma.
CALEB KABANDA: I could see people walking on this main road, fleeing the volcano.
NARRATOR: Caleb Kabanda, a local journalist, witnessed the whole eruption from the center of Goma.
CALEB KABANDA: You know, it was a lake of lava, destroying everything. I could see a lot of smoke and the lava flowing and wrecking all houses. You could hear the noise. I was very scared.
NEWS REPORT (BBC NEWS 2002 CLIP): The lava has been flowing for two days now. It shows no sign of stopping.
CALEB KABANDA: Some places, you could see the fire burning. Many people panicked, because it was a disaster to the whole city. You see all the houses you knew were destroyed. It was really terrible, and, for…this is the end of Goma.
NEWS REPORT (BBC NEWS 2002 CLIP): As if the people of Goma had not suffered enough, this was a day that brought them more death, more tragedy. Fireballs filled the sky after a petrol station here exploded. Fuel cans leapt into the air.
NARRATOR: Eruptions like this are no surprise, because Nyiragongo is part of one of the largest volcanically active zones on Earth: the East African Rift, a vast scar created by the pulling apart of the land.
It's believed this is happening because, deep in the earth, volcanic magma is rising, pushing up on a massive continental plate, slowly splitting it in two. If it continues, Africa will eventually break apart, creating a new ocean, the first to form in 30,000,000 years. Nyiragongo is in the center of this giant geological tear. There have been two major eruptions in the last 40 years. There is little doubt it will erupt again, with the same catastrophic consequences.
Back on the volcano, overlooking the crater, the science team considers tomorrow's descent. It will be a difficult and hazardous climb, but it's the only way they can study the lava lake up close.
ALDO KANE: That is full on. From where we are, here, to get down there, is over 400 meters. So, that's what? Four times Big Ben? And that's where we hope to camp, down there, on that that second level.
KAYLA IACOVINO: That's terrifying. That is absolutely terrifying.
NARRATOR: As terrifying as it appears, the volcano is also mysterious. As Chris explains, it's not completely understood why it erupts at all.
CHRIS JACKSON: This, this is a volcano. Beneath this volcano, and all other volcanoes in the world, is a magma chamber or some molten body of rock. It's magma from this chamber which rises up into the volcano, and it's changes in pressure within this magma chamber that gives rise to eruptions out of volcanoes. Here at Nyiragongo, we have a lava lake. In theory, there shouldn't be any pressure building up in here. All of that pressure should just be oozing and venting out of the surface without eruptions. However, we do know that this volcano…it's common to have dangerous eruptions from the flank of the volcano.
NARRATOR: Flank eruptions, like the one in 2002, can be lethal. The science team believes that intense activity, deep underground, increases pressure so rapidly that lava forces its way out of the volcano's side. So, they need to find a way to measure changes and pressure deep underground. But there's a problem.
CHRIS JACKSON: It's very difficult or almost impossible to directly measure changes in magma pressure directly within the chamber. One thing we can do is look at changes in the lava lake itself.
NARRATOR: The constant activity of the lava lake and the gases venting from its surface are not only a spectacle, they provide clues about pressure changes inside the magma chamber, partly due to the buildup of gases such as carbon dioxide, water vapor and sulfur dioxide. And some of these volcanic gases pose a deadly threat.
In fact, these gases are found in the ground throughout this whole region, and they seep out, creating a potentially fatal danger for the people and animals that live here. Volcanologists Dario Tedesco and Mathieu Yalire are in a village, just outside Goma, to warn the local people about this deadly side effect of living here. Mathieu has gathered them around a pit that appears innocuous but contains an invisible and deadly gas.
MATHIEU YALIRE (Goma Volcano Observatory): (Translated from Congolese French) Building in this place is endangering your families, your livestock and yourselves.
NARRATOR: The gas is carbon dioxide, though the locals have another name for it, "mazuku."
MATHIEU YALIRE: Mazuku mean "evil wind."
NARRATOR: The gas slowly seeps up through the cracks in the rocks, through the pockets of magma that underlie this whole area. At concentrations of just seven percent, it silently kills within minutes, by suffocating its victims. Matthieu and Dario head down into the pit…
DARIO TEDESCO (Campania University): Twenty percent already, fifty percent.
NARRATOR: …and discover levels of carbon dioxide…
DARIO TEDESCO: Seventy percent.
NARRATOR: …as high as 90 percent.
More people are killed by mazuku than by volcanic eruptions, and because carbon dioxide is heavier than air, it pools in depressions all around this area, so children are especially vulnerable.
MATHIEU YALIRE: (Translated from Congolese French) Because this area is volcanic, it comes from beneath the ground. The only thing it does is cause people's death.
NARRATOR: Here at the Goma Volcano Observatory, scientists have set up a network of seismic stations to keep an eye on activity across the region. These stations detect tiny tremors set off by lava as it forces its way to the surface, a telltale sign of a new eruption. Geologist Josué Subira monitors it all.
JOSUÉ SUBIRA: (Translated from Congolese French) It's possible to locate seismic events and understand where eruptions might happen. The traces we see here are data of earth movement, arriving in real time. And each trace corresponds to a station that is directly sent to the map.
NARRATOR: On top of Nyiragongo, Josué and the science team are planning to install the first seismic station on the volcano itself. But getting to the right location means a difficult and dangerous hike, along the razor-edged crater rim.
NICOLAS D'OREYE (European Centre for Seismology): If you're a goat, it's easy. Just watch your feet and keep, always, at least one hand free to recover your balance.
NARRATOR: After a precarious two-hour walk, Belgian scientist, Nicolas d'Oreye finally finds a good spot.
NICOLAS D'OREYE: This is simply a piece of flat stone, so we have a flat surface to have the seismometer resting on.
NARRATOR: The network needs sensors in many different places, so the scientists can establish the depth and location of volcanic activity.
NICOLAS D'OREYE: We are interested in knowing exactly where the signal comes from. If you have several fractures making progress towards the surface, it might be a problem, if it starts to become shallower, and then, that's an eruption.
NARRATOR: For Josué, this network of seismic stations is vital, because more stations give scientists a better chance of predicting an eruption.
JOSUÉ SUBIRA: (Translated from French) We have made progress since 2002. It's just in numbers. We had two, now we have 16. And it gives us a better understanding of magma activity, to warn people of an impending eruption and to evacuate in time.
NARRATOR: Although this seismic network in the region is improving, it isn't a foolproof way of detecting eruptions. If the lava flows through existing cracks in the rocks, the seismometers won't register any tremors, so the team needs additional ways to monitor the volcano, to evacuate people and save lives in the city of Goma.
First light on the crater rim: the priority is to get down to the lava lake as soon as possible. The weather conditions are miserable, but at this altitude it can get a lot worse.
ALDO KANE: The temperature is slightly warmer in there, but it can change like that, and it can go down to freezing. My team were down there yesterday and were caught out in a hailstorm.
NARRATOR: Torrents of water stream down the loose crater wall, creating treacherous rock falls.
ALDO KANE: There are waterfalls coming all down the side of the volcano, knocking massive rocks coming flying towards us.
NARRATOR: For Aldo, the risk of bad weather means a change of plan.
ALDO KANE: What we want to do is cut the amount of people that is going down into the volcano to essentials only, and that…Kayla, I was speaking to you earlier on, and you mentioned you can do a lot of your stuff up on the top here, so, I'm happy to, to keep you up here and not take you down there, because of that.
KAYLA IACOVINO: I can do all of the work that I need to do, basically, on the rim.
There's definitely some mixed emotions behind me not being able to go down. There's a bit of relief, because it, it is so dangerous to do. And, and there's also a bit of disappointment, because, you know, one-in-a-million experience to spend a couple of nights in the crater, next to a lava lake. It's something I could never have dreamed of being able to do.
NARRATOR: When the weather clears a bit, Aldo decides to start the descent.
CHRIS JACKSON: I can feel my heartrate going up, just putting the harness on.
ALDO KANE: Just wait till you look over the edge.
Last bit, before we go down: kicking rocks off. If you do kick a rock off, big shout, "Rock!" If one of these rocks hits someone on the head, it will kill them, even with these helmets on.
CHRIS JACKSON: I think I'm ready.
ALDO KANE: You should enjoy the view first before we go over, because after that, you're going to be fairly dizzy.
NARRATOR: Nyiragongo's crater has three levels. Tier 1 is a small outcrop almost a thousand feet below the crater rim. A sheer 250-foot drop below Tier 1 is Tier 2, where the team will be camping; and finally, Tier 3, the bottom level that surrounds the lava lake.
ALDO KANE: How you feeling?
CHRIS JACKSON: A blend of excitement and nerves, I'll be honest with you, yeah.
NARRATOR: Climbing down is the most dangerous part of the expedition, but even more so for Chris…
ALDO KANE: Nice and gently, Chris.
NARRATOR: …who's not an experienced climber.
ALDO KANE: How does it feel?
CHRIS JACKSON: Better now I've just come over the edge.
NARRATOR: And in such a remote location, if something goes wrong, there are no rescue teams, no helicopters to take an injured climber out.
ALDO KANE: Try not to do that, because there are sections, if you do that, the whole slope will go. All of this is just waiting to fall.
That wind's just picked up.
CHRIS JACKSON: Yeah, yeah, I can feel it.
ALDO KANE: Be careful not to kick anything. If you kick anything, it's coming down on my head.
CHRIS JACKSON: Everything's moving…nothing is stable.
CHRIS JACKSON: Sorry.
ALDO KANE: Have a look back up.
CHRIS JACKSON: Yeah, yeah.
ALDO KANE: Yeah that's good, that's good. You okay?
NARRATOR: With the weather holding, the rest of the team also starts its descent.
ALDO KANE: Just watch your feet coming down.
NARRATOR: After almost three hours on the ropes, Chris is more than halfway down and about to be lowered down about 250 feet, to the campsite below.
ALDO KANE: That's where we're heading, to, to the basecamp down there.
CHRIS JACKSON: Okay.
ALDO KANE: First one's going to be Chris, over?
NARRATOR: To do this safely, Chris is suspended on what's known as a Larkin frame…
ALDO KANE: Make yourself comfy.
NARRATOR: …a piece of gear brought down by Aldo and his climbing partner, Daz, during preparation for the descent.
CHRIS JACKSON: Rock!
ALDO KANE: Chris is down.
Spot on, that is very good.
CHRIS JACKSON: Oh, too intense! Don't look back. Don't look back.
So, I made it down to T2. Daz is just sorting out the ropes to be sent back up for the next victim. But the first thing I notice, as soon as I come down to this level, these giant chasms, maybe a meter, maybe two meters wide. You can see in the distance the, the campsite that's been set up.
NARRATOR: Tents have been pitched between two potentially fatal hazards: the vertical drop down to the lava lake is less than a hundred feet away, and just behind the tents lies a field of fallen rocks from the crater wall. Despite the danger, for Chris, the landscape is literally out of this world.
CHRIS JACKSON: If I was to compare this environment to anywhere else, I'd say Mars. There's just blacks and whites and reds, you know, it's very simple colors everywhere.
There is no vegetation whatsoever. There doesn't seem to be anything living down here. One of the reasons is actually, what I'm smelling is, it's sulfur. And all around us, there's these vents which are spewing out sulfur, into the air.
NARRATOR: Sulfur gases, which Chris smells, are just some of the toxic gases released from the volcano. By now, Benoît has also descended down to Tier 2, hurrying to prepare his first experiment, because time in the crater is limited. He hopes to monitor the level of the lava lake to learn what's going on inside Nyiragongo.
Unlike most volcanoes, Nyiragongo erupts from cracks in its flanks, but like all volcanoes, it erupts when pressure builds in its magma chamber, deep underground.
If the team can measure that pressure, it would provide a warning sign of an eruption. But the magma chamber is at least a mile below the surface, so it's impossible to measure any pressure changes directly. Benoît suspects, though, the lava lake itself may reveal those pressure changes.
BENOÎT SMETS: Here we have the chance to have this big lava lake, and you can see the lava as a magmatic chamber at ground surface.
NARRATOR: The plan is to use time-lapse photography to record any changes in the lake level, but when the lava lake is wreathed in venting gases, it's hard to see. To penetrate these clouds of gas, Benoît's cameras detect light in the infrared part of the spectrum, invisible to our eyes but not to the camera.
BENOÎT SMETS: I made this box myself. My box is made of a microcomputer, which will control everything. A real-time clock, to have an accurate time, and a camera. It's a small camera, like you have on your smartphone, and it will take every 10 seconds, and by comparing these pictures, I will be able to see the variation of the lava lake level.
ALDO KANE: Okay, Daz, lowering Jeff out.
NARRATOR: As evening falls, the other team members finally descend.
ALDO KANE: Lowering you into the cauldron
NARRATOR: Aldo is the last to come down, in complete darkness.
The next morning, Benoît returns to his cameras to see if they've worked and whether they can reveal anything about pressure in the magma chamber.
BENOÎT SMETS: Whoa! We've got a beautiful lava lake level drop, compared to yesterday at the same time. It's great. So, we recorded something special.
NARRATOR: To Benoît's expert eye, the camera has recorded a drop of about 15 feet within the last 24 hours. Benoît believes the most likely explanation is that there has been a slight drop in pressure within the magma chamber. A slow rise and fall in the level of the lava lake suggests stability, as opposed to what's known as gas "pistoning," rapid and violent changes in the lake level. Benoît has witnessed that behavior in other volcanoes and believes it's driven by dramatic variations in magma pressure.
It's also been reported before previous eruptions from Nyiragongo.
BENOÎT SMETS: It's not about having the lava lake level higher or lower, it's understanding these movements to predict a big event, like a flank eruption, for example, because that's what happens before the last two flank eruptions. So, we had big movements of the lava lake, and all this may say something about an upcoming eruption.
NARRATOR: Benoît's cameras are capable of spotting these abrupt changes, but they haven't yet been designed to be left in the crater and watched remotely, so the team needs to find another way to warn the people of Goma of an impending eruption.
Volcanologist Jeff Johnson thinks he can do this by listening to the sounds Nyiragongo produces, but not just any sounds.
JEFF JOHNSON: This is a custom-built microphone, and it's capable of recording sounds beyond the threshold of human hearing.
NARRATOR: Jeff's microphone is designed to pick up very-low-frequency sound; what's known as "infrasound."
JEFF JOHNSON: Volcanoes speak at low frequencies. They generate sounds that we can hear, but they also generate this world of infrasound; a unique voiceprint that we want to recognize and understand, so that when that tone changes in the future, we will be able to understand what's going on.
NARRATOR: If Jeff is right, then, like an organ pipe, this tone will change as the level of the lava lake rises and falls. Using sound in this way has great potential, and Chris Jackson is eager to see how it works.
CHRIS JACKSON: So, we're listening to sounds coming from the lava lake, is that right? We're trying to hear the lava lake with these sensors?
JEFF JOHNSON: The infrasound is detecting motions that occur both at the lava lake surface and also inside this bowl that can be vibrating. You don't think of a caldera this big as being an air mass that may be going up and down, but that's what we have discovered. The crater actually acts as a musical instrument.
NARRATOR: First, the scientists need to install the microphones. To detect this low-frequency sound, Jeff and Chris place groups of sensors at several locations around Tier 2 of the crater, as close to the edge as they dare.
JEFF JOHNSON: Go from here to there and from here to there.
NARRATOR: And it's not long before they're getting results.
CHRIS JACKSON: So, we've collected some data; it looks like a bunch of wiggles on a screen to me. What noise is the volcano making?
JEFF JOHNSON: Right, so we can't hear infrasound, but we can speed it up and make it audible. Here's an example of the infrasound being sped up by a factor of 40. This, to me, is exciting. I see the data; it's good, good quality, and I am happy.
NARRATOR: Even more exciting is the possibility of leaving a network of microphones in the crater to detect changes in the sounds the volcano is making. On its own, or with Benoît's images of the lava lake, this data could give scientists precise clues to the volcano's behavior. And for the people of Goma, it could lead to better early warnings of an eruption.
CHRIS JACKSON: So, it would be fair to say that infrasound could help better protect the people of Goma from a volcanic eruption?
JEFF JOHNSON: So, I'm a scientist, and I'm naturally cagey about answering a question like that, but, yes, I do believe that infrasound is a fundamental tool for volcano monitoring. And not too far down the road, we will be able to use infrasound monitoring here to better forecast Nyiragongo's next eruption.
NARRATOR: Up on the volcano rim, Kayla has yet another idea for an early-warning system. She studies the gases that constantly vent from the lava lake's surface, because she thinks they can tell her what's happening in the magma chamber.
KAYLA IACOVINO: The real power in gas measurements is that it can tell us about the entire system, miles and miles beneath your feet. That's where the action is, that is the driving force of volcanism. It's controlled deep down in the guts of the volcano.
NARRATOR: All lava contains gases, but when an eruption is building, those gases change. The most worrying gas is sulfur dioxide, because an increase often signals that lava is moving up towards the surface. By placing a device called a gas box where the volcano vents, Kayla can measure the amount of sulfur dioxide coming off the lava.
KAYLA IACOVINO: Sulfur dioxide is the kind of gas that bubbles out of the magma in the really shallow part of the system, so just beneath the lava lake. If we see, all of a sudden, a huge spike in the amount of sulfur dioxide that's coming out of the crater, that could be something that happens before an eruption.
NARRATOR: After 12 hours, Kayla returns to the vent to find out what's been recorded.
KAYLA IACOVINO: So, I'm just looking at the data now, and I'm pretty happy. So, these are sulfur dioxide. We're getting some readings there, less than one part per million, but there is some rating there. And it's something that we should keep an eye on to, to try to predict future activity.
NARRATOR: Kayla sees this low reading as good news, suggesting new magma is not rising up through the volcano. For the moment, Goma appears safe. But sampling gases is unreliable, because it depends on weather conditions and wind direction. Perhaps a combination of early warning techniques is needed to protect Goma, but no warning system is perfect. So, one key question remains: if the volcano starts erupting without warning, how long will people have before the lava reaches the city?
That depends on its chemical properties, which determine how quickly it flows. To estimate the speed the lava will travel during the next eruption, the team needs fresh samples. Ideally, they would take samples directly from the lake, but that's simply too dangerous. There is though, another possibility. During preparations for the descent, Aldo witnessed a new vent opening up…
ALDO KANE: Holy shit…
NARRATOR: …that sent rivers of lava running across Tier 3, the crater floor.
ALDO KANE: That's supposed to be heading down, but this aggressive vent here is, is constantly boiling. And the, I mean, you can see there the lava bombs that are getting blown out of there are probably 40, 50 meters into the air.
NARRATOR: For Aldo it was terrifying.
ALDO KANE: There's just so many …
NARRATOR: Now the vent is simply smoking, but the lava flows it left behind could be what the scientists need. So, the team plans to descend to Tier 3. First though, they need to check that the lava has cooled enough to walk on.
CHRIS JACKSON: We're about to launch a thermal camera, fitted to a drone, that the Belgian science team have brought along. And it's going to be flown over T3, the lower most level next to the lava lake, specifically to look at where there may be hot rocks or magma underneath the thin crust.
BENOÎT SMETS: If you go over that, we know they are about 60 degrees, so this would be like something we can use for….
Don't go over the lake!
ALDO KANE: He's flying back this way.
BENOÎT SMETS: There's, there's something really hot there. Could be… I have a problem with the drone, I can't control it.
ALDO KANE: Is the drone…have you got control?
BENOÎT SMETS: No. Maybe you can move, try to keep the signal.
ALDO KANE: Yeah, I think here, if you just watch the… So, we're, kind of, almost over the area that we'll be running the ropes in and abseiling down, won't we? Was that safe enough for tomorrow that we…?
OLIVIER NAMUR (KU Leuven): I think that's fine, as long as we don't go too close to the vent, which was really hot. But everything else was okay.
BENOÎT SMETS: I'm coming back because I cannot control the drone. The wind is too strong.
NARRATOR: The drone's thermal camera shows that the place the team wants to collect samples from is about a-hundred-and-forty degrees Fahrenheit, not too hot to walk on. At the edge of the cliff face, Aldo starts preparing the climb down for Olivier Namur, who studies the chemical composition of rocks. He thinks samples from the crater floor will reveal that the next eruption will consist of fast- or slow-flowing lava.
OLIVIER NAMUR: I'm interested in the composition of the lavas and the evolution through time. So, I've been sampling old lavas in the last couple of days, and I will be sampling these very young lavas that erupted last year on Tier 3.
ALDO KANE: I think it's round about a hundred meters. So, that's… I think where we are now is about the height of the White Cliffs of Dover?
DARREN "DAZ" PHILLIPS (Safety Advisor): Yeah, thereabouts.
OLIVIER NAMUR: I've never been down here before. This is going to be my first time.
NARRATOR: It isn't a straightforward descent. There's an initial 90-foot climb down, then a sloping field of fallen boulders, where the crater wall has collapsed, followed by a final vertical drop to the crater floor. It all has to be rigged safely, so Aldo and his climbing partner, Daz, descend first.
ALDO KANE: So, brittle.
That's both Daz and I on the boulder field, over.
Holy shit. Whoa, there's some big chunks of rock there, mate.
About a-hundred-and-fifty meters away from the lava lake at the minute, but I reckon Daz is, about 80 meters. So, it's about 80 meters straight down there.
NARRATOR: At the foot of the cliff, there's evidence of a dangerous recent rock fall. And up on the boulder field, a sudden plume of sulfurous gas means Aldo has to wear a breathing mask.
ALDO KANE: Oh, man. Look at these rocks. Just precariously balanced. If any of these rocks decide to go, then that's it.
NARRATOR: When Aldo drops over the edge, Daz stays up on the boulder field to keep an eye out on the rock face.
DARREN PHILLIPS: Yeah, I can see this bit, across to our left-hand side as you're climbing, looks right dodgy.
NARRATOR: As he descends, it's clear any false move could create a lethal rock fall.
ALDO KANE: There's stuff under here mate, the size of minivans, just hanging on by a thread.
NARRATOR: Even up on the camping level, Benoît can see the risk Aldo's taking.
BENOÎT SMETS: There are big rocks above you on the left. They look pretty scary.
ALDO KANE: So, I've just arrived at Tier 3. The lava lake is about a hundred meters that way, and that is the route I've just abseiled down. It is without doubt one the most dangerous things I've ever done. My mouth is dry and my heartrate is up; all the classic signs of 100 percent pure, unadulterated fear.
NARRATOR: All the classic signs that it's time to climb back up.
ALDO KANE: It is super sketchy. I think it's the most sketchiest thing that that I've seen since being in here. I don't know what you're used to, but I'm not entirely sure I would go back down there.
BENOÎT SMETS: If you think it's not a good idea, then not take a risk. And, I mean, we are here to do good science and collect exceptional data but not taking stupid risks.
DARREN PHILLIPS: I know you well enough to know that if that situation down there is…you're fearful of that, then…
BENOÎT SMETS: No, it's too dangerous. Let's forget about going to Tier 3.
NARRATOR: The descent to the crater floor is abandoned, but there is still another possible source of fresh lava. The vent activity Aldo witnessed during preparation threw out chunks of solid lava, or "lava bombs," and some may have landed on the boulder field halfway down to Tier 3. If they can be found, the science team will have samples of fairly fresh lava.
BENOÎT SMETS: For the rock samples, we can have some spatters coming from the vent in the boulder field.
ALDO KANE: It's not ideal.
BENOÎT SMETS: It's not ideal, but it's better than nothing.
NARRATOR: The team descends quickly, no one wants to hang around here too long.
ALDO KANE: I mean, you're standing hammering a cliff which is clearly already unstable…
OLIVIER NAMUR: Yes, this is true, but this is the only way to get these samples.
NARRATOR: Olivier soon finds what he was looking for, new lava bombs.
ALDO KANE: What have you got?
OLIVIER NAMUR: It's a very fine-grade lava. It's quite fresh. I think they will tell us quite a lot about the recent activity of the volcano.
NARRATOR: After an uneventful hour, he has enough samples. For a volcanologist they contain an unmistakable message.
OLIVIER NAMUR: Let me show you one of the samples that I collected from the active vent. We can see that this sample is a glassy black matrix. We can see a lot of bubbles here around and few tiny white crystals. We know that the composition of this volcano are low in silica, very low, below 40 percent. And this makes this lava very fluid. So, they have low viscosity. They will be flowing like water along the flanks of the volcano, rather than mud.
NARRATOR: Silica is a key component of sand but also of lava. The less there is, the more fluid the lava, and the faster it flows. Nyiragongo has some of the lowest-silica-content-lava on the planet, but there's another clue to the lava's speed in Olivier's sample, and it's not good news.
OLIVIER NAMUR: And on top of that, because they have only a few crystals, they decrease again the viscosity of these lava. But because they have only a few of these crystals, they are very fluid. I suspect that if there is a new eruption with this composition, it might be flowing even faster than 2002.
NARRATOR: In 2002, lava flowed toward Goma at reported speeds of up to 25 miles an hour. Olivier's samples reveal that next time it could flow more quickly. The people of Goma will have less time to evacuate, making the need for an effective warning system even more urgent.
The expedition is coming to an end. The team is getting ready to head out of the crater. The scientists have installed seismic stations around Nyiragongo and has have tested a variety of technologies to monitor the lava lake and detect the buildup of pressure in the magma chamber below.
The task is not done, but it's a good start.
KAYLA IACOVINO: Volcanoes can live for millions of years, and we're here for a couple of weeks. But we're getting the beginnings of an idea of what this volcano is capable of doing.
NARRATOR: It will always be dangerous to live in this highly volcanic landscape. As their work has revealed, for the moment, Nyiragongo is quiet, but it will not always remain so. The quest to understand this volcano and its fiery lake must go on.
CHRIS JACKSON: Nyiragongo is not an easy volcano to study. It's a massive headache in terms of getting people and equipment here. The motivation for it is very clear, there are a million people living very close to this volcano, so despite all the problems, it's worth it.
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A BBC Studios Production with PBS co-produced by NOVA/WGBH Boston.
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Into the Jungle Volcano Additional Material © 2018 PBS
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Additional Material © 2018 WGBH Educational Foundation
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This program was produced by WGBH, which is solely responsible for its content. Some funders of NOVA also fund basic science research. Experts featured in this film may have received support from funders of this program.
Original funding for this program was provided by Draper, Fidelity, the David H. Koch Fund for Science and the Corporation for Public Broadcasting.
Image credit: (Nyiragongo volcano)© Kirill Trubitsyn/Shutterstock
- Nicolas D'Oreye, Kayla Iacovino, Chris Jackson, Caleb Kabanda, Aldo Kane, Olivier Namur, Darren Phillips, Benoît Smets, Josué Subira, Dario Tedesco, Mathieu Yalire