This week - we’re exploding the science of volcanoes. Why do they erupt? What threat do they pose to aeroplanes? And what impact do they have on us and our environment? Plus, news that marriage cuts your mortality rate, what 800 million tweets have revealed about human moods, and the science behind the sound of a dripping tap...
In this episode
00:55 - Is getting hitched good for your heart?
Is getting hitched good for your heart?
with Professor Mamas Mamas - Keele University
Living in Holy Matrimony might come at the cost of some nagging, but could also save your life, as Marika Ottman found out from cardiologist Mamas Mamas from Keele University...
Marika - Want to cut your risk of cardiovascular disease? Getting married might be the answer.
80 percent of all cases of cardiovascular disease can be attributed to identified risk factors such as age, sex, and smoking. But what about the other 20 percent? A team at Keele University has identified marital status as a possible risk factor that could explain that remaining 20 percent.
I spoke with cardiologist Mamas Mamas to learn how getting married is good for the heart in more ways than one…
Mamas - Often in my clinical practice I have patients that come in and see me and they say to me the only reason that we’ve come in and seen you is because our wife told us to or our husband told us to. Which made me think that maybe marital status of a patient can give us additional information. That’s why I decided to look at the relationship between marital status and future cardiovascular health in these patients.
Marika - Worldwide there are many cases of cardiovascular disease and with that there have many studies conducted to determine their causes...
Mamas - What we did was a meta analysis. What that means is we looked at all of the studies that have looked at the question of whether marital status is associated with cardiovascular disease, and then combined the results from these 34 different studies from all over the world, conducted in two million patients, to get our findings.
Marika - After assessing over two million patient cases, Mamas and his team discovered results that were rather shocking…
Mamas - If you are unmarried you have a 40 percent increase in the risk of developing cardiovascular disease, or dying from coronary heart disease or stroke. We also looked at outcomes in patients or individuals with established cardiovascular disease. So, for example, patients that are admitted with a heart attack or admitted with a stroke and we find that, again, marital status is associated with much better outcomes in the married compared to the unmarried patients. Particularly patients or individuals that are divorced seem to have a much higher risk than their married counterparts.
Marika - Why are unmarried people more likely to develop cardiovascular disease? Perhaps the answer lies in the vow “in sickness and in health.”
Mamas - I work as a cardiologist and often, even today in my clinic, patients will always say, you know, I developed these symptoms. I didn’t think anything of them but my wife or my husband really pressurised me to seek medical attention. I think also there’s lots of spousal pressure to adopt a healthy lifestyle, so often men in particular after heart attacks who were smokers will get a lot of pressure from their wives to give up smoking.
Marika - So maybe nagging is a good thing?
Mamas - Yeah, perhaps. I think there’s also other straightforward things like if you have a stroke, for example, you have great difficulty in mobilising sometimes, and so having a partner that can actually take you to your rehabilitation, to outpatient clinics, and so forth, will really help in your recovery. Whereas single people may not have this social network to be able to support them through this. And we know that adherence to medications, i.e. whether your take your medications is much greater in married patients compared to unmarried or divorced patients.
Marika - But let’s say someone isn’t married but they’re living with a roommate?
Mamas - I think social relationships are really important. Part of the question is how close is that relationship with your roommate? I think that will impact on the health benefits. Certainly, any form of relationship would probably be better than isolation. We know that social isolation is associated with worse outcomes for a number of different conditions in medicine.
05:16 - What is cryptojacking?
What is cryptojacking?
with Chris Folkerd - UKFast
As our lives increasingly shift online, and computers continue to take over the planet, hackers and spammers and other dodgy operators are finding progressively more ingenious ways to separate us from our cash. And their latest ruse is to steal your electricity; not directly - but, instead, by getting your computer doing lots of power-hungry complicated calculations, the results of which they then sell to make money for themselves leaving you pay the power bill. And they’re hiding the system that does this in normal webpages and even online adverts so it’s really easy to fall victim without even realising. They call it “cryptojacking” and Chris Smith spoke to Chris Folkerd from web hosting company UKFast...
Chris F - My name is Chris Folkard. I’m the Director of Enterprise Technology here at UKFast.
Cryptojacking is the latest trend. Last year we saw a lot of cryptolocker where people were using cryptography to lock people’s machines and then extract payment. This year it’s changed to using their computers to generate money automatically rather than trying to get customers to pay.
Chris S - So this is the whole concept of mining for Bitcoins isn’t it?
Chris F - Yes.
Chris S - I suppose we should explain first of all what actually is cryptocurrency and how does it work?
Chris F - Cryptocurrency has been around for the last ten odd years and it’s a different way of representing currency. Traditionally it’s gold coins, it was something that you could handle. Nowadays people are moving to a more electronic form. There’s no inherent value to cryptocurrency; it’s got a value because people have decided it does. And all it is is a small package of information that can uniquely prove as yours and you can subdivide and trade with other people, and that’s all done with cryptography.
Chris S - Where do you get Bitcoins from? How are they made or minted?
Chris F - The easiest way for people to get them is to now buy them online. There’s exchanges where you can by your cryptocurrency. All they are is, effectively, a payment from a computer as a thank you for processing some work. So a Bitcoin is known as a distributed ledger, so it’s basically an account book and your PC will get a thank you for processing a part of that ledger and validating that it’s true. But as there’s more devices mining for it the maths behind it gets harder and harder so the value goes up because you have to do a lot more work to get the same reward.
Chris S - One statistic I saw was that actually mining for Bitcoins - so doing these computer calculations - leads to emissions of more CO2 from data centres than the whole of the country of Ireland!
Chris F - There’s been a lot of speculation around that. It certainly is a CO2 intensive operation. If you look at people who are doing it semi-professionally nowadays, they have extremely large numbers of arrays that are doing calculations all the time and that does utilise a huge amount of electricity.
Chris S - So if you can’t afford to either meet that electricity bill, build a big enough computer, or run a big enough computer the simple answer is you basically steal someone else’s computer indirectly via planting something on their machine that does those calculations on their machine without them knowing and does the work for you and sends you the results. Is that basically what’s happening?
Chris F - Yeah, pretty much. The electricity costs are now at a point where there is a tradeoff between whether it’s actually worth mining some of these currencies. So now it is very much use someone else’s resources, steal their electricity and then get the coin for free.
Chris S - How are people doing this?
Chris S - Oh god, that’s really sneaky! So by visiting a website you don’t even realise you’re actually trying to earn some money for the website owner and it’s basically your electricity bill that’s paying for that?
Chris F - Yep. Recent scans of the web found about 33,000 sites already, and that’s just well known sites that have started doing it in the background...
Chris S - Wow! When you say “well known” as in the kinds of sites that your average web user would visit?
Chris F - Yeah. They’re not necessarily going to be the high brand name ones, but a lot of the ones where you’re getting content for free. So free services are sometimes now subsidising themselves with some coin mining.
Chris S - And it doesn’t compromise the website performance?
Chris S - How would a person listening to this diagnose that they may have this problem?
Chris F - The biggest telltale sign is your PC will slow down. Unfortunately, that’s not unique to cryptojacking, that could be anything. But if you notice that everything’s started to run very slowly, either when you’ve got specific tabs open or where you've got an application open you can just go into “task manager” have a look at your CPU and it will show that it’s pegged at 100 per cent.
Chris S - Is it relatively easy to treat?
Chris F - Yes. That’s the good news is that a lot of the cases that are out there now are easily picked up by antivirus software. They will either block it automatically or tell you that the threats’ present; at the same time it stops these problems...
11:36 - Drip drip drip ... the science of a dripping tap
Drip drip drip ... the science of a dripping tap
with Dr Anurag Agarwal - Cambridge University
It turns out that the science behind why dripping taps sound the way they do is a lot more complicated than we first thought, and this week scientists at Cambridge University have solved the riddle of the reason why a drip sounds the way that it does. Chris Smith spoke to engineer Anurag Agarwal to find out why on earth he started studying the sounds of a dripping tap...
Anurag - I was visiting a friend in Brazil and it was the rainy season and it was raining very heavily. The bedroom I was in had a small leak and what my friend did was placed a bucket underneath as one would normally do to collect the water. At the beginning everything was fine but after about half an hour or so I started to hear the annoying plink noise that you hear with a dripping tap let’s say in your sink.
So initially this was very annoying and kept me awake but then I quickly became curious. I wanted to know why it was making this loud sound.
Chris - And critically, why the sound had changed. When the bowl was empty your didn’t get a sound and then as it got a threshold amount of water in it it began to make the plink plonk noise that you get.
Anurag - Yes.
Chris - And so the physicist and engineer in you kicked in and said I have to design an experiment to work this out?
Anurag - That’s right. We advertised it as an undergraduate project and we found a smart student, Sam, to work on it.
Chris - You’ve brought a demo: bowl, water, syringe. What are you going to do with them?
Anurag - Yes, I’ve got them here. I’ve got a full bowl with water, and I’ve got a syringe full of water, and what I’m going to do is I’m going to squeeze this syringe and release drops into this bowl full of water.
Chris - Before you do it in the water though, you did say that when you were in your bedroom in Brazil that when the bowl was empty to start with there was no sound so we’d better test that first.
Anurag - I have an empty bowl here, and if I squeeze my syringe in this, I’m just about to do it, the first drop is coming down…
Chris - Right. We’re listening really carefully.
Anurage - It’s hit, second drop.... third drop… fourth drop. As you can see this is very silent.
Chris - No, I can’t hear anything.
Chris - Okay. Proved by experimentation. I believe you. Then the bowl gets full.
Anurag - Now the bowl is full and I’m going to do the same thing again. I’m squeezing now. First drop…
Chris - Yeah. I’m definitely hearing the noises. Can I ask you to try something because you’re doing nice little individual drip, drip, drip. What happens if you do a more rapid stream?
Anurag - If I do this…
Chris - Now that is different. That’s louder. Is that the same thing but just many many times over so it sounds louder, or is there something else exciting going on?
Anurag - the mechanism here is different. We have just finished the research for this and it’s about to be published.
Chris - Ah. So you’re not going to give the game away?
Anurag - No. You’d have to invite me again.
Chris - How did you then go about modeling that then in order to work out what is going on.
Anurag - This is the interesting thing. When the water drop falls on a hard surface it makes almost no sound but, at the same time, when it’s falling on a soft surface it’s making a lot of sound, an annoying sound. This is counterintuitive.
So what’s happening is when the water drop falls on a soft surface like the water surface, the water surface caves in because of the mass of the drop following.
Chris - Ah, you mean the actual surface sinks a bit under the momentum of the falling drop?
Anurag - Exactly. And then what happens is that this cavity that’s formed wants to close because with the surface tension water wants to get back to its original level. But it does so very quickly, and in doing so it entraps an air bubble underneath. And this air bubble oscillates or pulsates at 5,000 hertz which is 5,000 times a second, and that’s the source of sound that we hear.
Chris - And it’s right in the middle of speech frequencies so we’re actually quite tuned into that.
Anurag - Actually it’s in the middle of the annoying speech frequency, which is between 1 kilohertz and 5 kilohertz. Other examples would be a baby crying which is in that frequency as well.
Chris - It’s very elegant you’ve been able to find out how this works, but can you extrapolate this and do anything useful with the model?
Anurag - One thing we can do with the model is to predict the amount of rainfall on an ocean. Because once we know the frequency that we are measuring we can tell what the raindrop size is, and from that we can estimate the amount of rainfall.
Chris - So what, would you put a hydrophone - a microphone under water - and listen to the rain falling on the ocean?
Anurag - Exactly that. That’s what we would do.
Chris - How do you resolve where the rain is falling? Because the water’s going to transmit vibrations from all over the place over a big area, small area. How do you resolve all of that?
Anurag - Localisation is hard but we can tell the total amount of rainfall so we can do a sum of all the rain that’s falling.
Chris - Forgive my ignorance, but is that a big problem facing marine scientists and hydrologists then trying to work out how much rainfall’s at sea? Because if there’s no-one there to measure it it’s a little bit of ‘who cares’ situation isn’t it?
Anurag - Well, if you are interested in the total amount of rainfall in a season and normally we do it overland in a certain place, then that could be interesting. But that’s not what motivated us.
Chris - No, indeed. And any other applications for that apart from getting someone a first?
Anurag - That was the best project in the year so the student was happy.
Chris - I’m not surprised. Very very exciting.
Anurag - But there is another application which is to synthesise sound. It is very hard to synthesise these kind of sounds. That’s because you would think that most of the sound is coming from the initial impact when the drop falls on the water surface, but from what I’ve said that’s not what happens. That initial impact is completely silent. It’s only when you get this bubble entrapped underneath, which is a few milliseconds after the initial impact do you get the sound.
Chris - Does that mean then it’s really hard to make an artificial raindrop sound?
Anurag - Yes, because people up to now didn’t know how to make it.
Chris - They were doing it wrong?
Anurage - Yes.
Chris - So you can solve that?
Anurage - Yes.
Chris - So can we look forward then to much better sounding rainfall made artificially in Hollywood movies and cartoons?
Anurag - Oh yes. Absolutely.
Chris - Have you licensed this? Have your protected this, or can everyone just read your paper and rip this off now?
Anurag - I think it’s pretty easy.
17:36 - Down to Earth: from spacesuits to stadium roofs - beta cloth
Down to Earth: from spacesuits to stadium roofs - beta cloth
with Dr Stuart Higgins - Imperial College London
How does a material developed for NASA spacesuits get onto stadium roofs back here on Earth? Here's Stuart Higgins...
Stuart - What happens when the science and technology of space comes Down to Earth?
Welcome to Down to Earth from the Naked Scientists. The mini series that explores the spinoffs from space technology that are being used on Earth. I’m Doctor Stuart Higgins.
This episode: how materials used in spacesuits developed for NASA for the Apollo missions continue to be used in stadium roofs around the world.
January 27th, 1967. A fire breaks out during testing of the Apollo I command module. The first of the missions aiming to take astronauts to the moon. Spreading rapidly through the flammable materials inside the spacecraft the fire kills the three astronauts onboard.
The tragedy led NASA to search for new fireproof materials for their spacesuits. Nylon had been used throughout the command module but had melted during the fire and the existing spacesuits failed to provide adequate protection.
A solution was proposed by two companies working with NASA. A new kind of fabric based upon woven glass fibre and coated with a non-stick plastic polytetrafluoroethylene, otherwise known as teflon. The called the new material “Beta Cloth” and it formed the outer shell of the updated spacesuits giving ten times greater fire resistance compared to what had been before.
And while spacesuit materials have moved on since the Apollo era, beta cloth found a new lease of life back on Earth as construction material. Walter Bird, an aeronautical engineer, realised the potential of beta cloth as an architectural building material, and in 1956, formed a company to take the tech further. The company specialises in tensile structures where the building materials are continuously held in constant tension.
They’re most commonly seen today as the curving tent-like roofs on structures like the O2 stadium in London, and many other sports stadiums around the world. The tightly woven glass fibres give the material its structural integrity, while the teflon coating reduces the ability of dirt and grime to stick to the roof allowing most of it to wash off when it rains.
The teflon polymer is made up of a long chain of carbon atoms each attached to atoms of fluorine. The configuration of electrons in the fluorine atom make it highly electronegative meaning it can strongly attract other electrons towards it. It’s the incredibly strong bond between carbon and fluorine atoms in the plastic that gives the useful non-stick properties.
Also when used in beta cloth, teflon’s white colour has the advantage of helping to reflect sunlight stopping things getting too warm inside buildings. The flexibility and strength of the material, along with its rapid installation, allows architects to explore different and interesting designs in their structures and has furthered its use.
So that's how a material originally developed for spacesuits for Apollo astronauts has become a widespread building material throughout the world.
20:50 - Can Twitter reveal our mood?
Can Twitter reveal our mood?
with Professor Nello Cristianini - University of Bristol
Twitter might reflect the mood of the nation, as we collectively share our thoughts with the masses, but can we use this data to answer serious scientific questions? That’s what a team at the University of Bristol wanted to find out. So, for over 4 years, they collected tweets, every hour, from the 54 largest cities in the UK. They then worked out what categories of words were being at any moment, and provided an indication into people’s moods at the time they were tweeting. Georgia Mills got the #story from study’s author Nello Cristianini...
Nello - The big surprise for us was there are indeed two different thinking modes. One morning orientated, one more night oriented. A morning mindset focussed on power, drive, achievement and that is a very strong signal. It peaks at 7am, 8am, 9am in the morning, and as the day progresses we see a change in this. And by the time you reach the late evening you start seeing a lot of he and she pronouns, male and female references. You start hearing negative emotions, swearing, and as you go on into the middle of the night, we have the moment when people talk about death. And just before the sunrise this is the moment when the religious topics peak. Then the sunrise starts and the cycle starts again.
Georgia - I think we can all relate to the existential dread in the middle of the night. But how did you pick apart the fact that these are trends happening to the same people because could it be that the people who are awake and tweeting at 6am are just more driven, and the people who are awake and tweeting at 3am are just more concerned about death and things like that? Could it be this is when different people are choosing to tweet?
Nello - Absolutely right. Obviously this is not the same one person tweeting. There are different people tweeting and we are sampling them. One could say there are different types of people and some of them are active at night and that’s entirely possible. And it’s hard for us to correct because we anonymise. However, I would argue that isn’t this the same point. Then you can ask right away why are those people who are interested in darker topics active at night? And why are those people interested in social concerns active in the evening after dinner? In a way, we are coming back to the same question again: why would they be active at different times?
Georgia - Have you got any ideas?
Nello - Well, we have conjectures but we don’t have anything. So this study really is carefully pointing out that this happens. As for causation, that's difficult. One thing we did we tried to ask a follow up question. Is it possible to summarise all this variation and explain it with a few factors. And we found that just postulating two hidden factors accounts for nearly 80 percent of all the variation, and they are cyclic, of course. One peaks at 6/7am the other one peaks at 3 am. They actually behave like some of the hormones we have. So although we cannot prove anything we do observe that this variation does correlate to some of our other hormones as well.
Georgia - Right. So this could be a flag that maybe it’s our hormones driving this change, but further work needed?
Nello - Further work is needed but we do have this suspicion. But for this paper, what we can report with confidence is the empirical observation that these things are cyclic. They have a 24 hour cycle and this is statistically significant.
Georgia - How many tweets would you say in total you have analysed?
Nello - 800 million tweets.
Georgia - Quite a big number. Is this going to change how we do research what you’ve done here? Is this just the tip of the iceberg?
Nello - Yeah. My hope this this; that we can start using these things in a good way. You could repeat the same study by looking at different types of data. For example, in the past, we’ve been looking at the log of the queries in Wikipedia. What are people searching for in different seasons? And we find various seasonal patterns in their queries. So data is becoming available. It’s open and if you have the right scientific question you can design a study and get an interesting answer.
Georgia - What kind of questions would you like to ask?
Nello - At this moment I’m still looking at seasonality and daily cycles of emotions and thinking patterns. Previous studies we have done show that there is an increase of negative emotion and sadness in the winter and we try to look at mental health. Many years ago we did demonstrate that you can use this to detect flu epidemics, so we are just exploring what is possible.
What is a volcano?
with Dr Jessica Johnson - University of east Anglia
Volcanoes have been in the news a lot recently, with eruptions in Hawaii and Guatemala; so this week we’re taking a look at the impact that volcanoes and eruptions can have on the environment, technology and our lives. Chris Smith spoke to volcanologist Jessica Johnson from University of East Anglia...
[transcript to follow]
32:15 - How do volcanoes impact the environment?
How do volcanoes impact the environment?
with Dr Evgenia Ilkinskaya - Leeds University
When a volcano erupts, there’s a plume of gas and a stream of magma. Now whilst magma can leave a trail of destruction, the volcanic gases also have a huge impact on the environment. This is something of interest to volcanologist Evgenia Ilkinskaya, who spoke with Izzie Clarke...
Evgenia - My favourite story is probably a relatively small eruption that happened in 2010 in Iceland. This little eruption was in the middle of nowhere up on the mountain. And at this point in time it was still very much winter in Iceland so it was very snowy and we reached the eruption site at about the time when the sun was coming up. So you had this virgin white snow and huge red lava fountains coming out straight from that snow and black ash deposits put down around the volcano.
So it was just that combination of colours: white and red and black, and it was just an absolutely fantastic scene. And it was making these sounds like an old school steam engine, a train coming past. I’m not particularly religious myself, but that scene was something you really felt in the presence of something bigger and much more amazing than anything humans could ever make.
Izzie - Evgenia’s research focuses on volcanic gases as a way to monitor volcanic activity and its impact on the environment and the atmosphere. And, it turns out, volcanic gases are rather important when it comes to attempting to understand these mountainous pressure pots.
Evgenia - They can first of all tell us what is happening underneath the volcano. They can tell us whether molten rock or magma, as we call it, is moving towards the surface. If there’s fresh magma being injected into the volcano. Once an eruption starts, we can use the gas to measure how big the eruption is. If it’s becoming smaller and so on and so forth.
Some of the most abundant gases in magmas are actually water, carbon dioxides, and then sulphur dioxide. Sulphur dioxide is something that you might hear volcanologists talk about a lot. It’s a very important gas because it’s relatively easy to measure but it also has quite important environmental implications because it can be quite toxic.
Izzie - Now sulphur is a complicated beast and can exist in many forms. In volcanoes it comes out as hydrogen sulphide, which actually smells like rotten eggs, or more commonly sulphur dioxide, which is acidic. It can sting your throat, your nose, and your eyes and is definitely something to avoid. Plus, it takes its toll on the environment…
Evgenia - If people remember the London pea soup fog back in the 1950s, that was actually caused by sulphur dioxide which was being emitted by coal burning power plants, but volcanoes definitely emit this. We can visually see it in the atmosphere; it sort of tends to be a blue, brown, grey cloud and you can really see impacts on vegetation, so not a lot of plants can survive in this kind of environment.
Sulphur dioxide can impact climate. It tends to happen in very very big explosive eruptions. So think about the Pinatubo eruption in the Philippines in 1991 or El Chichon eruption in South America in the 80s. These are huge eruptions and the eruption column goes up to tens of kilometres up in the stratosphere, so higher up than planes even fly. If that happens, gases, in particular sulphur dioxide, can stay up in the atmosphere for very long periods of time, so months or years, and in those scenarios we can start to see climate impacts around the globe.
Actually what happens is that sulphur dioxide with time in the atmosphere gets converted into tiny tiny particles, and those particles reflect incoming solar energy making the climate actually cooler than it was before. Living organisms that are very sensitive to small changes in temperature will react differently or habitats can start to change if it’s a really long lasting effect.
Izzie - Carbon dioxide is also released in a volcanic eruption and we hear so much about it in the news. So could this be having an affect on climate change?
Evgenia - Carbon dioxide is one of the very common gases in volcanic emissions, and it is a greenhouse gas which means overall it would warm the planet. And that is a reason our planet is warming at the moment is because human activities are producing so much carbon dioxide. In comparison to how much human activities are producing, volcanoes are producing actually very very little carbon dioxide, something like only 2 percent.
Izzie - Ah right. So we’re causing more damage then. But is there any way we can use volcanoes to our benefit?
Evgenia - It’s very important to remember that volcanoes are not just destructive forces. While volcanoes produce some carbon dioxide they can actually be used to capture carbon dioxide, so removing it from the atmosphere and thereby reducing the effect on climate that humans are having. This is something that is being experimented on in Iceland very successfully where they’re taking carbon dioxide out of the atmosphere and pumping it back into the volcanic rock and making it stay there.
Another very interesting way of possibly using volcanoes is people tend to like living on volcanoes because volcanic soils are quite fertile. And also in hotter countries, living up on the flanks higher up on the volcano means that the climate is a lot more pleasant, and a lot of plants are grown high up on volcano flanks. For instance coffee is produced in a lot of countries with active volcanoes.
Izzie - And that’s not all. Volcanoes produce a lot of power and this can then be used to heat homes and water for those nearby.
Evgenia - Geothermal energy works when you have heat coming from molten rock deep down in the ground that is heating groundwater around it and this groundwater can be several hundreds of degrees hot. This superheated steam can be taken out of the ground and piped to communities and either just be used to then heat cold water for showers etc., or to drive steam turbines to generate electricity. It’s fantastic to see this where it’s well set up. In Iceland, something like nine out of ten homes are heated entirely by geothermal volcanic energy. Energy like this is very very cheap.
Of course volcanoes, we can only use very little percentage of the energy that volcanoes are able to generate so there’s a lot more to do with volcanoes and discover how we can harness the energy much better.
39:60 - How do volcanoes affect a jet engine?
How do volcanoes affect a jet engine?
with Anna Young, Cambridge University, Jess Johnson, University of East Anglia
Many of us remember being stuck and grounded in 2010, very long queues at airports with no-one going anywhere. In fact, it became the largest global air traffic shut down since World War II, and it happened because of an Icelandic volcano called Eyjafjallajökull. The ash from volcanic eruptions can cause catastrophic damage to aircraft engines. But how? And what can we do about it? Chris Smith spoke to Anna Young from the Whittle Lab in Cambridge University, and later Izzie Clarke spoke to the University of East Anglia's Jessica Johnson. Firstly, Chris asked, why is sand a problem for engines?
Anna - Basically, the ash is sand and sand can cause quite a lot of damage to the engine on its own, in the first place. But, because of its larger surface area, it can melt more easily and when it turns into glass in the hot parts of the engine that can cause really really big problems.
Chris - These are jet engines that we’re dealing with here, that’s what you work on. So can you just explain for people who are not familiar just explain very briefly how a jet engine works?
Anna - Sure. When you’re walking up to your plane the part you can see is the fan - big set of spinning blades. And the job of the fan is to pull the air into the engine and about 90 percent of the air goes through the fan and then out through the nozzle at the back where it’s pushed out quickly, and that jet going backwards creates thrust to drive the engine forward.
Now the job of the rest of the engine is to use the other 10 percent of the air to drive the fan. So the air that’s not gone through the bypass goes into the compressor where it gets squeezed to a much higher pressure. And then it goes into the combustion chamber where we burn fuel to add energy.
Next we’ve got hot, high-pressure air and that goes through the turbine, which is another set of spinning blades that takes energy out of the air and uses that energy to spin the fan and the compressor. So the turbine uses hot air to drive the fan which produces thrust to drive the engine.
Chris - I went to a talk by someone from Rolls Royce and they summarised and said it’s suck, squeeze, bang, blow. It sucks air in at the front, squeezes it very hard and gets it hot, chucks a load of fuel in which burns, and then they extract energy at the back end having blown the gas stream out to then drive that fan. But I suppose one should point out that the gas stream in there is at very high temperature isn’t it? It’s like 1500 degrees C inside the engine when the fuel’s burning?
Anna - Yeah. At the entrance to the turbine the air is, as you say, about 1500 degrees, and that is hotter than the melting point of the turbine blades.
Chris - The engine’s running at a temperature beyond its melting point, so why doesn’t it melt?
Anna - What we do is we take some air from a cooler part of the engine from part way through the compressor, and we drill tiny little holes in the turbine blades and we blow that cool air through. That cool air creates a film that keeps the turbine just under its melting point basically.
Chris - Ah. So you’re protecting the surface of the blades with a very thin cushion of slightly cooler air so any incoming gases are sort of going to ride over the blade without touching it.
Anna - Yep.
Chris - If I chuck in whole bunch of sand and volcanic dust, what does that do to the system?
Anna - It’s likely to turn to glass because as well as being hotter than the melting point of the turbine blades, that part of the engine is hotter than the melting point of the ash. So we get glass which clogs up all of those little holes and then we won’t have any cooling air and the turbine will melt.
Chris - Then you get a sort of ‘hot spot’ on the blade, and what will that do cause it to weaken or change shape, deform, distort?
Anna - Yeah. I think it’ll happen pretty quickly at that point and the blades will start melting so then you haven’t got a turbine to drive your fan. The other thing that happens is that air has to go somewhere, and where all the air from the rest of the compressor goes is the combustion chamber. So we have the wrong mix of fuel and air, so that can make the fire in the combustion chamber go out and then you’ve basically switched your engine off.
Chris - And then you lose power catastrophically?
Anna - Yeah.
Chris - Given that we know this, what can aircraft operators do to minimise the damage to their engines - just not fly?
Anna - Essentially, yes. In my lab we spend a lot of time simulating the flow of air through the engine. You could do that and people have done it where you add in the flow of the sand as well, but the problem is that is a very complex process and a very big calculation. So, probably by the time you’ve got your answer as to where the glass is going to form your volcanoes stopped erupting because you need such a big computer and you’ve got to leave it for so long.
Chris - But engineers can say “oh, don’t fly” when there’s a volcano, but pilots may not be able to avoid one if one suddenly goes off. So, under those circumstances, obviously they could try to avoid the ash cloud but there are potentially going to be particles going into the engine so what does that do, just shorten the lifetime of the engine?
Anna - Yeah. If it’s just a case of more straightforward sand which isn’t going to melt then the front part of the engine bears the brunt of that. If you’ve ever been on the beach on a windy day and the sand gets whipped up into your face and it stings, if you imagine doing that at 600 miles an hour that's what happens to the fan and the compressor, so the sand particles blast the blades.
We design the blades very carefully. The tolerance on them is around the width of a hair and then you’re blasting random bits off with sand, suddenly you don’t have nice, smooth shapes that you designed and the air won’t pass as smoothly through. So you start losing efficiency, you start using more fuel. If that’s a commercial plane that means you’ve got to pay more for your ticket, and you’ve probably got to start replacing bits.
Chris - Presumably, if you do end up with this sort of damage to the engine, this can be monitored and you could replace the blades that are worn?
Anna - Yes, yes you can. And one of the things that we do in our lab is we look at different forms of damage and see when is it bad enough that it needs to be replaced.
Chris - Yeah. So you basically know what the ‘safe’ threshold to operate on is?
Anna - Exactly.
Chris - Right then, better just stay on the ground in that case! That was Anna Young from Cambridge University.
Izzie - Jess Johnson is also here from University of East Anglia. What about other technologies? Can volcanic eruptions affect what’s going on at home as well?
Jess - They can, yes. People who live near volcanoes probably do have to deal with some of the issues associated with them on a day to day basis. Particularly if there is ash, it could be drawn into their electronic equipment. Your computer usually has a fan to cool in down in the same way that it could damage the jet engines, but not quite the same way. But the ash can clog up the computers, damage the computers, clog up air conditioning units and things like that.
Ash also acts in a very strange way when it gets wet. It gets quite heavy and almost cement-like and so if you have an accumulation of ash on your roof or on your gutters and then it gets wet then it can be very very heavy. There have been cases of people that have flat roofs, those roofs collapsing under the weight of the ash.
Izzie - My goodness. Obviously, if we have an eruption all of that gas and that ash can get redistributed over the globe so can that also then move onto other areas and perhaps impact people’s lives in other ways as well?
Jess - Yeah, absolutely. Depending on the size of the eruption the ash column can get into different layers of the atmosphere and be distributed. It can affect the climate and it can affect crops as well.
Chris - While we’re talking about gases and things, Jess, there have been reports in the past of volcanoes that are belching up gases which then, being heavier than air, flow down into valleys and settle in low points and asphyxiate people. Is that just apocryphal or does that happen?
Jess - That does happen, yeah. I think the famous example was in Cameroon where there was a bubble of CO2 that got released from a volcano that had a water lake inside it. And, yeah, because CO2 is one of the big gases that is released from volcanoes, and it is heavier than air, it does just settle in a valley and, yeah, people died because there wasn’t any air to breathe, there wasn’t any oxygen.
Chris - When you talked about mud just now I wondered if you were also going to talk about the manifestation that’s happened in Guatemala with mud flows?
Jess - Exactly.
Chris Because one of the things that Izzie was talking about was the Iceland eruption and the fact that there was a lot of snow. And so you’ve got a lot of heat with a lot of snow which creates a lot of water so you get this toxic combination of mud formed because you’ve got ash with water and the whole thing turns into a big catastrophe?
Jess - Yeah. We call the “Lahars” and they’re a very common phenomenon. What happens is it can happen during the eruption if there is an eruption during a heavy rain or a monsoon. You can have water and the ash mixed together and cause a very fast flowing mud flow which can be very damaging. It can happen during the eruption, or it can happen at a later date if the ash has accumulated on the volcano and then there is an addition of water. So, ice melting or a rainy season or something like that, the ash can be remobilised, can cause big landslides and mudflows. And, as I said before, this stuff is like cement so it can be really really damaging.
Izzie - Absolutely. Now what about some of the gases that get into the atmosphere? We heard about global cooling and what are some of the problems with the gases that are released as well? Because we heard about asphyxiation, but can they poison crops and things like that?
Jess - They can, yeah. Sulphur dioxide, one of the main gases that’s released from a lot of volcanoes, when it mixes with water it causes sulphuric acid, and that can cause acid rain that can erode metal and can also poison crops and livestock. People who live downwind of Kallawaya, for example, will be very familiar with what they call “vog,” it’s volcanic fog made up of sulphur dioxide.
50:39 - How can volcanoes impact us?
How can volcanoes impact us?
with Dr Lucy Jones - Calfornia Institute of Technology
How do volcanoes affect people's lives? Izzie Clarke spoke to seismologist Lucy Jones from California Institute of Technology and author of The Big Ones - How Natural Disasters Have Shaped Us. First Izzie asked Lucy what happened in Pompeii....
Lucy - We all have the image that everyone was buried in their homes and died because we found those corpses when Pompeii was excavated. But actually the eruption began with what’s called the Plinian eruption where the gases and ash head high up into the atmosphere. It turned everything black; it terrified people, and we know that about 90 percent of the people left during that period and survived.
About 10 percent said hey, rocks are falling on your heads, I’m staying in my home. And then were trapped there when what’s called the pyroclastic flow came through, which is when the gases lose the impetus up into the atmosphere. And as they’re heavier than air they flow down at tens of kilometres per hour, sweeping through and burning everything on touch.
Izzie - How do we know how many people this actually affected?
Lucy - The Romans had decent tax records and numbers of people that lived in the area and we can compare it with the number of corpses that were found in the excavation.
Izzie - Throughout the show we’ve also heard about these gases that are thrown out after an eruption, so how far can they travel globally? Does it only affect just the people near that eruption?
Lucy - Oh, absolutely not. It depends upon the explosive force of the volcano and how far up into the atmosphere they go. But as long as they aren’t just at the surface, like we’re seeing in Hawaii right now, they get up into the atmosphere, they travel over. And, in fact, in 1783 there was a massive eruption in Iceland. It was called the Laki eruption, and the gases that came out from there essentially poisoned all the crops and animals in Iceland. They were both fluorine and sulphide gases and the only thing to eat had to come out of the ocean. The whole country of Iceland came very close to extinction.
But then the gases travelled on and moved out over Europe, but now the gases were much more intense and concentrated. Our estimate is that 23,000 people died in the summer of 1783 just in the UK. Comparing death records of that summer with other summers, reports of a fever and burning throats and looking back it’s like okay, they were being poisoned by these gases in from Iceland. And then there were further deaths across Europe so they can travel a very long ways.
Izzie - Gosh. Are there any other knock-on effects? We heard about this global cooling so can that cause a big problem?
Lucy - Oh, it can be huge. Once you get out of the immediate Earth surface you get into the atmosphere, travel over to Europe. If it gets up into the stratosphere then it can travel around the world. In the stratosphere it’s much drier and, therefore, these particles, which actually are heavier than the air and in the lower atmosphere get washed out relatively quickly, can last for years up in the stratosphere.
Again, back in 1783, we had the poisons in the UK and in Europe, and then global cooling because these sulphide particles got up into the stratosphere and blocked the sunlight. It stopped the monsoons which depend upon a temperature differential of between the continents and the ocean. Without monsoons, the Nile didn’t flood and over 600,000 people starved to death in Egypt because of it. And, in fact, there were famines in both India and Japan that were partially caused by this that killed over 11 million people.
Izzie - Do we know what the likelihood is of having another eruption somewhere like this?
Lucy - The probability’s 100 percent. Just give us enough time. And, of course, whether it happens this year or next century - that’s a random distribution - there are many volcanoes around the world that are capable of doing this, that have done it in the past, and it’s absolutely certain that it will happen again.
Now, because of modern technology, if we instrument a volcano, we are much more likely to be able to predict that it’s happening. But you need the instruments, you need a warning system to communicate it. And, as we just saw in Guatemala, you’ve got to be able to get the warning to the people who are actually going to be affected and that takes time and sometimes you don’t have enough time.
We really need to be ready for that humanitarian crisis. We need to have resources to help people because it is going to be happening at some point.