Volcanoes can pose major dangers. The eruption in 2022 of the underwater Hunga Tonga volcano in the South Pacific alarmed scientists. It was the most powerful ever measured with modern instruments. Do we need better early warning systems?
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00:00 The Phlegraean fields in southern Italy. Could a supervolcano soon erupt here?
00:06 The ground is rising alarmingly.
00:09 Now the ground is increased of 110 centimeters in the center of the caldera that is Pozzuoli.
00:21 At an ancient Roman plaza in the city of Pozzuoli, traces of marine algae show that the earth here has risen and fallen over the centuries.
00:29 Some shifts have been sudden.
00:31 I was in front of my store one morning opening everything up when suddenly the earth dropped by 10 or 15 centimeters.
00:40 It was a pretty dizzying experience, kind of like someone pulled the ground from beneath my feet.
00:48 Volcanoes. That's the focus this week on Tomorrow Today, DW's science program. Welcome to the show.
00:58 Two-thirds of the Phlegraean fields are underwater. Around a third remain above the waves.
01:07 Pozzuoli is at the center of the caldera. The area covers around 150 square kilometers in all.
01:14 The region is viewed as what's called a supervolcano. That's not a scientific term, but is accepted by the research community.
01:22 An eruption known as the Campanian ignimbrite is behind the designation.
01:27 It's been calculated that originally this great arc covered an area of 7,000 square kilometers.
01:36 So practically all the Campanian area was destroyed by this eruption.
01:42 So it was a very impressive eruption, unimaginable for us.
01:48 To classify volcanoes, researchers look at factors like how much material they eject and how high.
01:54 What's known as the volcanic explosivity index rates them between 0 and 8.
02:00 On that scale, the Campanian ignimbrite is thought to have been a 7.
02:04 A massive volcanic eruption in the Pacific helps illustrate just what that means.
02:09 It was only rated a 5 or 6.
02:14 In January of 2022, an island in the South Pacific came close to being wiped off the map when a volcano exploded right underneath it.
02:22 This eruption is the highest intensity eruption we've ever recorded on modern instruments.
02:27 It's one of the highest plumes we've ever recorded, you know, 55 kilometers,
02:31 punching right through our stratosphere up until the upper layers of the atmosphere.
02:35 And mechanisms by which we've never seen.
02:37 It's the first time we've ever had a country go absolutely dark in the aftermath of an eruption.
02:44 This is where it happened, in the archipelago of islands that make up the kingdom of Tonga.
02:50 For the first time on record, an eruption unleashed tsunamis in two different oceans.
02:56 Two people died in Peru as a result of that tsunami.
03:01 It really showed that you can have an eruption on the other side of the world.
03:04 And that shockwave was recorded in every single country.
03:08 The accompanying sonic boom was heard over 9,000 kilometers away in Alaska,
03:13 while the gigantic plume of ash was visible from outer space.
03:17 When it descended, it devastated homes, roads, bridges and fields, and contaminated drinking water.
03:26 Satellite images show how neighboring islands were covered in a carpet of volcanic ash.
03:32 And this really made us realize that we weren't prepared for these kind of even larger volcanic eruptions.
03:39 So we're talking 10 or even 100 times or even 1,000 times larger than Honka Tonga.
03:45 Mike Cassidy is a volcanologist at the University of Birmingham in Britain.
03:50 His specialty is the causes of eruptions.
03:53 For him and fellow researcher Lara Mani from Cambridge University,
03:57 the eruption in Tonga was a wake-up call for the entire field of volcanology.
04:02 They wrote an article urging their peers not to underestimate the risks.
04:06 We believe that the risk of a large magnitude eruption is around one in six this century,
04:11 which is a roll of the dice.
04:14 Volcanoes often form where tectonic plates converge.
04:17 They're common in the ring of fire that rims the Pacific.
04:20 Around one in ten people live in danger zones surrounding active volcanoes,
04:25 a risk that's greater than many think.
04:27 An asteroid impact is far less likely, but is the kind of danger that gets a lot more media coverage.
04:35 After a meteorite exploded over the Russian city of Chelyabinsk in 2013,
04:39 NASA and other space agencies pumped a further wave of money into planetary defense systems.
04:47 The DART mission alone cost around 320 million U.S. dollars.
04:54 And yet for volcanoes, it's not the same picture.
04:58 There are estimates of like a global monitoring kind of system would cost around 370 million.
05:04 And if you think for that sum of money, that very small sum of money,
05:09 we could have a global monitoring system for volcanoes,
05:11 it kind of begs the question, why hasn't that already happened?
05:15 In 2010, the eruption of Iceland's Eyjafjallajökull was relatively weak,
05:20 but its reverberations were felt around the world.
05:24 As ejected lava was chilled by the ice around the crater, it fragmented into tiny, sharp particles.
05:30 The resulting cloud of ash posed such a danger that Europe's airspace was closed.
05:35 In total, over 100,000 flights were canceled, almost half of global air traffic.
05:40 This was really interesting. It was significant enough in its scale and size to cause real global disruption.
05:47 Nobody knew really what to do.
05:50 And that led to catastrophic impacts to just-in-time supply chains,
05:54 mechanical pieces and perishable goods.
05:58 And the global economic impacts were the largest ever recorded at that time,
06:03 around 5 billion to the global economy.
06:05 So anything that stops global trade and volcanic eruptions can do that.
06:10 That could spell kind of wide catastrophe in lots of different sectors.
06:15 The uninhabited island of Hunga Tonga Hunga Haapi was itself only a few years old,
06:22 formed in the aftermath of a volcanic eruption.
06:25 The explosion in 2022 also shredded an undersea cable,
06:29 severing communications between Tonga and the rest of the world for over a month.
06:36 All that remains of the island now are two small promontories.
06:41 We shouldn't be looking at Tonga like, "Oh, well, thank God that wasn't worse."
06:45 It should be like, "Actually, Tonga was really bad and we shouldn't be seeing anything like that,
06:50 and we certainly shouldn't be seeing the impacts on that scale again."
06:54 And as for the wider impact of that cloud of volcanic ash,
06:57 there's plenty of work ahead for climate scientists, too.
07:02 If our blood is red, why are our veins red?
07:07 Now to your questions.
07:08 If you have something you want to know from the world of science,
07:11 just send us a video, text or voicemail.
07:14 If we feature your question on the show, we'll send you a little surprise as a thank you.
07:21 This week's question, of course on volcanoes,
07:25 comes from Noemi Rosa Rebollo-Franco in Mexico.
07:30 Where does carbon dioxide in volcanic eruptions come from?
07:39 For billions of years, volcanoes were among the largest sources of greenhouse gases such as carbon dioxide.
07:47 The CO2 emissions from volcanoes probably prevented the Earth from permanently turning into an ice planet.
07:54 The carbon dioxide comes from inside the shell structure of Earth.
07:59 At its center is a solid iron core with a liquid outer layer.
08:03 Above this is the Earth's mantle in which hot rock rises, cools and sinks back into the depths.
08:12 Volcanoes are found on the Earth's outer shell, the so-called crust.
08:17 It does not form a rigid surface.
08:19 Instead, the crust consists of plates that float and move on the viscous mantle.
08:26 Where an oceanic plate meets a continental one,
08:29 carbon-rich sedimentary rock from the ocean floor sinks into the crevices where it is heated.
08:36 Inside the Earth, the pressure and temperature are so high that volatile substances such as CO2 dissolve into the liquid rock.
08:45 Bound in hot magma, this dissolved CO2 reaches volcanoes.
08:52 When it rises through the vent, the pressure decreases,
08:57 and the gases bound in the molten rock are released into the atmosphere.
09:03 Besides water vapor and CO2, volcanoes also emit other gases such as sulfur dioxide, hydrochloric acid and methane.
09:14 The amount and mixture of gases depends on the chemical elements and minerals that make up the magma.
09:21 Researchers have studied CO2 emissions from volcanoes around the world and found big differences between them.
09:29 How much CO2 a volcano releases into the air depends not only on the volume of ejected magma.
09:40 There are layers of rock underground where the mantle is heavily enriched with carbon.
09:46 These reservoirs can also enrich rising magma with carbon dioxide.
09:52 This happens at Mount Etna in Italy, for instance.
09:58 It blows 9,000 tons of CO2 into the air every day, about 10% of the emissions of all volcanoes worldwide,
10:07 a much larger amount of CO2 than can be dissolved in its molten rock.
10:12 How this happens exactly is still unclear.
10:15 The Kilauea in Hawaii, on the other hand, spews four times more magma to the surface,
10:20 but it only releases a third as much carbon dioxide, meaning it probably does not have a carbon-rich reservoir underground like Mount Etna in Italy.
10:30 The threat of a potentially huge eruption in the Phlegraean fields is making headlines.
10:40 Volcanologists are alarmed by the changes in the area's emissions, chemistry and temperature.
10:46 This is the reason for which most scientists are talking about this volcano, because it is in arrest.
10:54 And it is a dangerous volcano because it is explosive, it is largely populated, so the volcanic risk is very high.
11:06 One challenge for researchers is recognizing dangerous volcanic activity at an early stage.
11:12 We looked at a project in Germany to see what they watch out for.
11:17 The greatest risk of a volcanic eruption in Germany slumbers here.
11:24 Things have been explosive at Loch Lake before, in some ways like the Hunga Tonga eruption.
11:32 About 13,000 years ago, the earth spewed forth.
11:36 It was a six on the volcanic explosivity index.
11:41 It was a really powerful eruption, comparable to the Hunga Tonga eruption in January of 2022.
11:48 Craters filled with boiling lava. There are no active volcanoes like this in Germany.
11:56 But there are volcanic fields, large areas prone to seismic activity.
12:01 The East Eifel region sits on one, with Loch Lake at its center.
12:05 The Eifel region is still not really monitored, although there is the possibility that eruptions will occur here again.
12:13 Of course, it would make sense to do more with the techniques we have today,
12:17 to better monitor volcanoes globally and also in specific regions.
12:22 Insights into past eruptions can be gained by looking at the chemical composition of volcanic rocks.
12:29 Loch Lake is surrounded by a ring wall of rock debris.
12:32 For earlier researchers, proof of what's called a "mar volcano",
12:36 where explosions form a kind of funnel-shaped indentation that then fills with water.
12:41 But because Loch Lake is very large for this type of formation, recent research tends to classify it as a caldera.
12:48 For a long time, the volcano was considered extinct, with future eruptions deemed unlikely or impossible.
12:55 But is its peaceful face no more than a mask?
12:59 Scientists are now taking a closer look at the Eifel region.
13:03 This is a special area here. It shows what's called "distributed volcanism".
13:12 That means the volcanic hazard should be assessed quite differently.
13:16 Torsten Damm's team wants to uncover volcanic activity by examining this cave.
13:22 The eruption 13,000 years ago left behind basalt lava.
13:26 The volcanic rock proved to be a desirable building material and was mined here for centuries.
13:32 What remains is a hewn-out, cellar-like space.
13:35 The mine is also a great place for research for a different reason.
13:53 It's very quiet. There's no disturbing ambient noise, such as street noise or rain.
13:59 That makes it ideal for eavesdropping on what's going on below the surface.
14:03 We want to measure minute earthquake signals, and that's best done when you're on bedrock,
14:11 such as here, on the old basalt flow.
14:14 Another possible sign of volcanic activity comes from vents called "muffets".
14:21 Does the carbon dioxide in them come from new rising magma?
14:25 In addition to volcanic quakes that occur at great depths,
14:29 muffets are also indicators of molten rock deep beneath the surface.
14:34 This is an indication that we really do have molten rock here in the Eifel, in the upper mantle.
14:43 The exciting question is, of course, whether this molten rock will escape.
14:46 Can it penetrate the crust, maybe even reach the surface?
14:51 To find out, a network of 350 measuring stations has been set up in the region.
14:57 Eruptions like that of Hanga Tonga are a reminder that volcanoes are still not well understood.
15:05 Data from the measurement campaign in the Eifel region can lead us to profound new insights.
15:15 Today, for instance, we know that there isn't just one single magma chamber.
15:20 It's spread over many levels.
15:23 It's no longer easy to say whether it's active or not.
15:27 The areas at greater depths may be molten, while the upper areas may have hardened, but could be reactivated.
15:34 We assume that we may have a good example of such a system here,
15:38 and that it could provide an example for how to study one.
15:42 First, however, the measurement data from the campaign in the Eifel region have to be evaluated.
15:48 The Phlegrian field sits on top of an especially large magma chamber that also feeds nearby Mount Vesuvius.
15:58 The chamber is around 10 kilometers beneath the surface.
16:02 Magma is largely made up of silicates, gases and suspended crystals.
16:06 Depending on its makeup and surrounding pressure gradient, the molten rock can heat up to between 700 and 1250 degrees Celsius.
16:14 One lab is studying magma dynamics using an unconventional model.
16:19 Lorenzo Mantelloni is cooking something up at the German Research Center for Geosciences in Potsdam.
16:27 It's a volcano made of gelatin and clove oil.
16:31 Being a cook is also part of the research here. I never mind being both.
16:37 I also enjoy cooking. And this is not so satisfying actually.
16:41 Gelatin, like, it stinks a bit. It's quite sticky.
16:44 Lorenzo directs the liquid gelatin into a transparent container in the fridge,
16:50 where it will firm up into a model for volcanic activity.
16:54 Delicious.
16:56 Lorenzo will then use the gelatin volcano to study paths that magma can take beneath the Earth.
17:02 We let the gelatin rest in the fridge for 20 hours. And this is enough for it to solidify and to settle down.
17:09 These black paper dots help visualize how the gelatin substrate rises as magma pulls up.
17:16 I am measuring a quantity, a parameter, that gives the idea of how much pressure you have to exert on the gelatin to obtain a certain deformation of the gelatin.
17:28 Lorenzo Mantelloni has added clove oil to the gelatin.
17:32 That leads to the formation of a lens-shaped magma chamber in the model.
17:37 Magma can't be observed or tracked in real time, and little is known about its movements underground.
17:42 But this transparent model at least provides a glimpse of how molten rock can make its way to the surface.
17:48 What is going to happen now is that I am going to inject some air with this needle.
17:58 The air bubbles imitate new magma rising from the depths.
18:02 What you see up there is a magma chamber. So there is already some magma down there.
18:09 Maybe it's cooling down, maybe it's been there for a long time.
18:13 But somehow, for some reason, a new batch of magma is rising up from the depths.
18:18 And it's feeding the magma chamber.
18:21 At first, the magma chamber just swells, causing the gelatin, which represents the earth around it, to deform,
18:28 until the pressure rises high enough and has to be relieved.
18:32 Something is happening on one side.
18:35 The pressure is rising, and the gelatin is starting to melt.
18:39 The gelatin is melting, and the magma is rising.
18:43 The pressure has to be relieved.
18:46 Something is happening on one side.
18:49 Okay, now the magma is heading for the surface.
18:58 And the eruption just happened.
19:03 Of course, there are tremors. What you see on the surface, the gelatin shaking,
19:09 those are analogs for earthquakes.
19:13 By measuring how the surface deforms before an eruption,
19:17 the research team hopes to deduce where underground magma chambers are located in the real world.
19:23 After the model eruption, Lorenzo pumps in water containing red dye.
19:28 Its distribution reveals the whole system of tunnels and magma chambers, the gelatin volcano's architecture.
19:35 The stress field within the gelatin is going to dictate the pathway of incoming magma dykes.
19:42 We call them dykes. These are thin, but spread out cracks.
19:47 This is quite important, because if we have a model that can, in a way,
19:53 predict the trajectory that magma will take through the crust,
19:57 then we do have a way to forecast where future eruptions will occur.
20:03 And we are striving to find, if you will, rules that will allow us to predict where these pathways will end up in the surface.
20:15 In the real world, magma would have to push through different layers of rock.
20:21 But the gelatin model helps researchers better understand its movements in the ground beneath our feet.
20:29 If the Phlegrian fields do erupt in a big way, there are evacuation scenarios for the population,
20:35 but they're largely based on untried plans.
20:38 For me, what we can improve, so to prepare better people,
20:47 because people have to know what to do in case of an eruption.
20:52 Another active volcano is the Villa Rica in Chile. It's erupted around 50 times in the last 500 years.
20:59 When a volcano erupts, the animals in nature always notice first.
21:07 They start to roar. My father taught me that. It's a warning.
21:13 Villa Rica, 1971, a powerful eruption that the head, or "lonco," of the indigenous Mapuche people can still remember.
21:22 In his village, Villa Rica scorched the earth and left its mark.
21:27 Nevertheless, Manuel Segundo Chincoliv Payán remains here, at the foot of the volcano.
21:34 During the 1971 eruption, the volcano exploded at midnight.
21:41 It melted a lot of snow, and a lot of water came pouring down in our direction.
21:45 The next day, in the early morning hours, rocks also started coming down.
21:50 Violent mudflows called lahars set in motion by the volcano, one of the greatest hazards they can trigger.
21:58 Lahars form when hot lava and gases melt the snow at the crater, sparking an avalanche of mud and debris.
22:06 With temperatures of up to 100 degrees Celsius and speeds of up to 180 kilometers per hour,
22:12 lahars thunder down into lower elevations and can cover great distances.
22:17 They can destroy villages in a matter of minutes.
22:20 José Luis Paimo wants to detect lahars earlier to warn people who live at the foot of Villa Rica more quickly.
22:28 He does this by recording the sounds the volcano makes.
22:31 To do so, he's installed a station measuring infrasound at an altitude of around 1,400 meters.
22:38 This is a good place to install the sensors, because we are in a forest, and it helps us filter out ambient noise,
22:51 especially the wind.
22:53 To minimize the wind and noise, we place the sensors above the ground, but not too high,
23:00 so the forest here is an additional natural filter.
23:04 The sounds José records are low frequency, about one hertz.
23:10 They aren't detectable to the human ear, but José's microphones can detect them.
23:18 With a network of three microphones so far, the researcher has listened to how the magma inside the volcano behaves
23:27 and can tell when it's bubbling in the lake of lava inside the caldera.
23:32 But he's also recorded the sounds of lahars.
23:38 When the recording is sped up, the volcano's sound also grows audible.
23:44 [Loud wind]
23:46 [José speaking Spanish]
23:55 This way, we can detect the lahars close to their source, as they emerge, and we can also estimate their speed.
24:03 That allows us to give an earlier warning.
24:06 We are able to send an alarm signal in plenty of time, potentially before the lahar reaches a populated area.
24:14 However, no one can predict exactly how much lava Villarica will spew,
24:21 or whether mudslides or hot gas clouds will come racing down its slopes.
24:26 Volcanoes don't seem to follow any rules.
24:33 The historical eruptions of Villarica always occurred in different ways.
24:37 The last one, back in 2015, was different than the ones that happened in '84 or in '85,
24:44 and they were different from the one in 1971.
24:47 Rucapillán. That's what the indigenous Mapuche call the Villarica volcano, "House of the Spirit."
25:00 Their own traditional houses are called ruca.
25:03 I get up at night, at midnight or one, to look at the volcano.
25:12 I can see it well from one of our windows when the sky is clear, and some nights I see it spitting fire.
25:19 The volcano is a really great thing, because it's the breath of the earth.
25:29 A hot breath. And no one can predict Villarica's next great exhalation.
25:36 Time to wrap up this week's special episode of "Tamara Today" on volcanic research.
25:43 But if you still have a question about the field or the science involved, make sure to drop us a line.
25:49 Thanks for watching, and don't forget to stay curious. Bye for now.
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