 This is Think Tech Hawaii, Community Matters here. It's one o'clock on a Monday afternoon, so you must be watching Think Tech Hawaii research in Manoa. I'm your host, Pete McGinnis-Mark, and my guest today is my really good friend, Professor Lionel Wilson, who is an emeritus professor at Lancaster University in England, and also an affiliate faculty member here at UH Manoa. So Lionel, welcome. Thank you. I know that you're just visiting here for a few weeks, but you've been here on many different occasions, so it's great to have you back in Hawaii again. And today we're going to be talking about some of the numerical models you do of volcanic eruptions. And as the viewers might be able to see, even our background image today is of a volcanic eruption, the Pu'u Ovent erupting back in 96. So tell me a little bit about what you do, Lionel. You look at volcanic eruptions, but… I do, yes. And I do this from the point of view of a physicist rather than a geochemist or a pathologist. Most people who look at volcanoes do work on the chemistry of the rocks, whereas my interest is the physics of what's going on, how fractures are open in the crust of the planet, and liquid rocks spills out in time. And you said the planet, and of course, I know you work a little bit on terrestrial eruptions. We're going to talk today about volcanic eruptions on the moon. Absolutely. And I'm sure that's a little bit different, even from a physicist's perspective. Oh, yes. In fact, it was when we first recognized eruptions on the moon that I got interested in this field and sort of asked the obvious question, well, wait, the moon's smaller than the Earth, the gravity is less, is that going to have an effect on the way eruptions take place? And it turns out to have a profound effect, in fact. And of course, the moon is a vacuum, so that may also affect the way you work. Yes, it does. Yes. In fact, if you think of the fire fountain eruptions on Kilauea, which everyone will have seen at some stage over the last few decades, the heights of those fountains are determined by how much the gas that's being released from the molten rock expands. And on the moon, because there's a vacuum, it expands much more. That means it accelerates. It throws material up to greater heights, spreads it to greater distances and so on. So, again, the major effect. Speaking of the moon, we've had a number of people on the show in the past talking about the moon. But let's just remind some of the viewers what the moon looks like. And here we've got, I guess it's the near side of the moon. It is. When you're looking at volcanoes on the moon, where do you look for them? Well, you basically look at the dark areas on this image. You notice that the dark patches are roughly circular generally. And that's because what's happened is that very large impacts on the moon have produced giant craters, placent, and they are the key places where eruptions are then taking place. So, all the dark material you can see is, in fact, lava that's flooded out into the depressions. And, of course, we know that it must be lava because we've got samples back from the Apollo mission. Absolutely, yes. Apollo missions all landed in these areas actually because they tend to be flatter and it's a safer place to land. But that was great for us because it meant that we got disproportionately samples of the volcanic rocks. And just to give our viewers a little perspective, when we're talking about volcanic eruptions on the moon, that's not today. That's way back in the history. That's a good point, yes. The moon's smaller than the Earth. And the size of a planet controls how well it conserves its heat. So the larger you are, the more slowly you cool. The Earth has not lost all that much of its internal heat. It's still active, of course. The moon and Mercury are both much smaller and they've lost almost all of their internal heat. So they stopped having eruptions about halfway through their lives. So we're looking at ancient eruptions. And ancient would be a few billion years old? Yeah, between two and four billion years old. OK, and of course the solar system's about 4.5 billion years old. It sort of died out. It's about the first half of the moon's history. It was active in the second half. It wasn't. All right. Now you're a physicist looking at lava flows. We're going to see a picture of lava flows on the moon. Next slide should show us something. All right. And explain to the viewers what it is we're looking at here. It's a black and white image. Sure. What we're looking at is the southwest corner of one of those very large basins that's flooded. And fish events have opened up in the area off the bottom left of the picture here. And so lava flows have moved across down a gentle slope towards the middle of the basin. And there are one or two mountains here and a fair number of craters. But you see the low bait features running from lower left towards the upper right. Each of those is on a lava flow. And what does the scale be? Are we looking at tens of miles? We're looking at a gap of about 150 miles across the screen. OK, so these are big flows. What would you do if you were starting to think about modeling a lava flow on the moon? So do you worry about the chemistry or do you worry about what is it that you do? We start by thinking about the chemistry. And of course, from the Apollo samples, we know what the chemistry, in general terms, of these lavas was. Only enough, we don't have any samples from specifically the flows on that last image. But we know measurements from orbit that they're extremely similar. So we can take the chemical properties. And of course, we can either actually melt Apollo samples in the lab, although they're very precious. So we usually make up things with the same composition, melt them, and look at how they flow. And as they flow easily, in fact, they do flow easily. They're very runny liquids. So we then say to ourselves, OK, if there was a fissure of a certain size erupting this material, how much do you need to erupt per second? And the fissure is actually the point in the ground. Yes, it's the fracture. It's the fracture liquid that comes out of. That's right. So the liquid comes out, just pulls onto the surface. It flows away. And we have to say, well, because of the effect of the low gravity, what will this do? Well, if you have a certain thickness of flow, it will flow more slowly because there is less force acting down the slope. The gravity affects that. And so if we see a flow of a certain thickness, that tells us something about the rate at which the volume per second of the liquid that must have been coming out of the fissure. So that's the first step. Then you say, ah, but this flow is 200 miles long. Can it have gotten that far without cooling? So you then do a calculation that says, how fast is it losing heat from the top? How fast is it losing heat into the ground? Can it flow this far? And you need a certain threshold, a certain discharge, to make it possible to make a flow of the size that we see. Size that you can observe. And does the vacuum conditions change the rate of cooling? Or is the heat lost down into the subsurface? Well, they're both issues. Of course, the mean having no atmosphere and slow rotation, it rotates once a month. So you have a two-week day when the surface gets very hot. So that reduces heat loss. But if the eruption happens during the lunar night, the surface is very cold. That increases the heat loss. Most of the eruptions probably took place for more than one lunar day. So it kind of tends to average out. But it is an issue. And yes, they lose heat at the top by basically very radiating into the vacuum. When you see eruptions on Earth, you may sometimes notice, well, you notice fume coming off the flow. And you notice turbulent clouds and fume. And just, well, of course, in our atmosphere, none of that happens. So you just have the hot surface radiating away into space. So you have to take care of that. And the examples which we saw in that image. Any idea how long they would have been active in order to produce the flow? To flow that far, something like one Earth day. Is that all? Yeah. They were very high discharge rate eruptions. That's remarkable. Do we get such high discharge rates on Earth? We do. And in a sense, they would represent very dangerous eruptions. They flow faster than you can run. If you weren't in a vehicle, you wouldn't have run one of those. But the good news is they only happen on the Earth every 10 to 20 million years. So it's nothing we should be lying awake in bed worrying about in the short term. But those things do happen periodically. We see them in the geological record. And they are very impressive eruptions when they do happen. They must be. And presumably, they have an impact on the Earth's atmosphere as well as everything else. Yes. Essentially, all volcanic eruptions bring not just liquid rock, but also gases from the interior of the planet. On Earth, the communists went to water and carbon dioxide and some sulfur and other things. But of course, you release those gases into the atmosphere and sulfur dioxide and carbon dioxide are both greenhouse gases. So at least locally and for very big eruptions, probably at least the whole hemisphere, you modify the atmosphere enough to. Well, you have two effects. You can either induce heating, or actually, if the sulfur gases condense in the upper atmosphere, they form little droplets that reflect the sunlight. And you can actually reduce the temperature as a result. So again, it's a complicated issue to work out exactly what the consequences of a given eruption are likely to be. So I guess if some of our viewers are wondering, what's the point or what's the purpose of doing the numerical modeling of eruptions on the moon, here's a great. Yeah. It's giving us an insight into what the, if you like, the rare, but very important punctuations in the Earth's geological history can be. And an obvious one is we all think of the end of the dinosaurs. And that's clearly a link to the fact there was a large impact crater at the time. But there were also a number of large volcanic eruptions in India at the time. And most people now suspect it's the combination of the consequences of those two events, lasting over centuries that was the critical trigger. Right. So your studies can actually tell us a little bit about styles of volcanism sometime in the Earth's history. Yes, they'll try it, yeah. And of course, they have a bearing on understanding the eruptions that we see today. Let's take a quick look at another slide, because we're getting close to a break. But let's just take a look. Here we've got an eruption on the Earth, all right? And we're seeing what I infer is a lava flow that might be, say, five or six meters thick. Yeah, that's a very broad. And it's got the flowing interior. And so when you're doing your numerical models, you have to worry about not only the volume, but how the surface actually changes over the course of the eruption. Yes, that's true. In fact, what you're seeing in this image is a very rough, clinkery surface on the top of the flow. And that's due to the way the flow is cooling. It's trying to produce a nice, smooth layer of chilled lava. But it's being deformed all the time by the movement of the still liquid lava underneath. And that causes fractures to develop. And so you get the very rough clinkery on the top. At that level of detail, or sort of in a general sense, your models can accommodate this kind of changes? Yes, basically they can. We have to rely on making melts of this material in the laboratory and making measurements on them with instruments that forcibly deform them so we can measure the rate of this thing, deform. But if we take that into account and look at the cooling rate, the rate at which you chill into the surface, and then how you stress it by the deformation from underneath, you can see how the cracks develop and how you get the clinkery surface. Can you assume that the eruption temperature for lava flows, say, on the moon would be similar to the ones that we have here or now? Roughly speaking, yes. Although, in fact, looking at the chemistry of those rocks and thinking about what the conditions must have been like inside the moon where the melting took place, it turns out that they would, in fact, have been erupted at higher temperatures than most of the eruptions we've seen here in Hawaii. You mentioned the gases that contain on Earth. Are they present as well? Some of them. It's an interesting issue. For the longest time, we used to think the moon was very dry in the sense of having no water at all. And as instruments, you know, the technology has gotten better over the years. We found traces of water in the Apollo samples. So we now understand that when the eruptions took place on the moon, a small amount of water was released during the eruptions. So it turns out, again, from looking at the chemistry, the main gas that was released was carbon monoxide. Not carbon dioxide, which is the common one on Earth, but the other oxide, carbon monoxide. And it's just a consequence of the subtle differences in the chemistry of the rocks. Interesting. Well, we're getting close to a break line, but when we come back, I'll be particularly interested, what are you doing here in the sense of why does somebody from England keep coming back to Hawaii? I know you've been here a number of times. We might delve a little bit into that issue as well as science in England as well. But let me just remind the viewers that you are watching Think Tech Hawaii research in Manoa. I'm your host, Pete McGinnis-Marc, and my guest today is Professor Lionel Wilson, who is an emeritus professor at the University of Lancaster in England, as well as being a full faculty member at UH Manoa. And we'll be back in about a minute. So see you then. This is Think Tech Hawaii, raising public awareness. Living in this crazy world So caught up in the confusion Nothing is making sense Likeable science on Think Tech Hawaii. Every Friday afternoon at 2 p.m., I hope you'll join me for likeable science, where we'll dig into science, dig into the meat of science, dig into the joy and delight of science. We'll discover why science is indeed fun, why science is interesting, why people should care about science, and care about the research that's being done out there. It's all great. It's all entertaining. It's all educational. So I hope to join me for likeable science. And welcome back to Think Tech Hawaii Research in Manoa. I'm your host, Pete McGinnis-Marc, and my guest today is Professor Lionel Wilson, an emeritus professor at Lancaster University in England. Now Lionel, I know you've been back to Hawaii several times. Quite a number of times, yes. Apart from the weather and the beaches, why do you come here? Well, basically, because two things, you have active volcanoes of the kind that I'm interested in looking at. Volcanoes here are of the same kind of lava that we find on the Moon and Mars. And also, you have a group of superior scientists who've been working on these topics for a long time. And we have great interactions and thinking through how to improve how we understand these eruptions. Sure, I think so. What do you do? Do you go into the field with these researchers or do you stare at images? Well, for the planets, I stare at images because that's where we get our information. I do go into the field. We said earlier, my background is in physics rather than geology and geochemistry and so on. So it's good for my soul to go into the field with people, look at the rocks, talk, think through what are we seeing, what does this mean? Then I can take that information back and hunch over the computer and make models of what we've been looking at. And is it mainly Kilauea that you work on? Here in Hawaii, yes, yes. It's been such a rich fund of information over the last decades. OK, and you mentioned that you each has world-class scientists. What's the situation in the UK as far as planetary research or people who are working on volcanoes? Right. Well, people working on volcanoes, people often ask why do we have a volcanologist in the United Kingdom at all? We don't have any active volcanoes. You'd have to go back about 300 million years to find an eruption in England. But of course, we do still have responsibilities for some overseas territories. And we have one that's still active, Montserrat in the Caribbean, which erupted over the last few, well, the last couple of decades. So, and in the past, we were responsible for volcanoes in Africa, for example. So, there was a tradition from that point of view. But it's evolved much more towards understanding the theoretical background. And I think that's the major thrust. And the planetary research in the UK? We, the UK, it has a national space agency. We take part in ESA missions. ESA is the European Space Agency. The European Space Agency, yes, that's right. Via the links with the European Union, which are a matter of dispute at the moment, but it's not going to that. Yes, but it's just that the planetary work has never been a major source of funding in the UK. It's there, and it keeps going. But it's just not such a large emphasis. And certainly ESA, the US Space Agency, has grown all these fabulous missions. It's been responsible for producing so much information. So, there's motivation for you to come? Yes, of course. Let's take a look at another slide, because I know you brought along a number of images. Now, what is it we're looking at here? It looks like all intents and purposes are river valleys. It does, doesn't it? Yes, and when we first saw these valleys, they are valleys on the moon. I hope everyone's seeing it as a snake in depression. And the sun shining from the right-hand side, right? The sun is shining, yes, from the right, that's right. So, there's a prominent crater quite close to the middle. And then the slaking depression, this valley. And just for a very short time, people said, oh, there were these old river valleys. But there's a number of problems. The Apollo samples did not contain more than microscopic traces of water. The moon has no atmosphere. It would appear it never had an atmosphere. So, if you put water out on the surface, the first thing it does is boil. And it vanishes very quickly. So, the next fluid, which was a likely candidate, was of course lava, since we realized that the rocks we were getting back were largely volcanic rocks. And it then became an issue, well, yes, but how do you erode what looks like a river channel using lava? We're not used to that happening on the earth. Lava comes out of an event of some kind and flows across the countryside. And you get a positive feature, a lava flow. How do you get a depression? And the answer, which finally dawned on people as well, if the eruption goes on for a long enough time, then the heat that you're leaking into the ground under the flow eventually warms up the ground to the point where it starts to melt. If the ground is an old lava flow and you have a new lava flow, by definition, if this is molten, it's hotter than that. And what's more, this has a melting temperature less than that of the flow. So if you heat it up enough, it starts to melt. And as it begins to melt, different minerals melt at different rates, so you start to disaggregate the surface. And then just the fact that you've got liquid flowing over it begins to tear bits away and you slowly erode a channel into the ground. So it's carved into the pre-existing landscape. That's right. And if you do the calculations, it takes about a week to warm up the ground. And most of the eruptions we see here in Hawaii, individual eruptions don't very often go on for more than a week episode to do, but in one place. I guess Monolow in 84 went on for about three weeks, but that was really rare. So that's right, it's rare. And so that had the potential to just be beginning to warm up the ground underneath those flows. But these eruptions on the moon went on for months. So that's why they were able to warm up the ground, start to strip the ground away. And you would have a situation. I mean, that channel, I've gotten the exact depth, but it is some tens of yards. Well, in fact, I know you bought that particular image because I believe that was Hadley Wheel where some of the astronauts went. And the next image will actually show. Yes, there you go. I'm not sure if this is Jim Irwin. Right, with the rover. At the rover, but... On the rim of the valley. It explained to us a lot about what we're looking at. Yes, we're looking into this meandering valley, standing on the rim, looking down into the floor. And you can see the sloping sides, where originally these would have had nearly vertical sides because you'd have cut vertically down nearly into the ground. But of course, they've crumbled away. Micrometre, old bombardment, you're breaking up the rock. Let's just remind the viewers what we're looking at is a ground photograph of that same channel that we saw in the previous image. So here, I think what you're telling us, Lionel, is that we're seeing a channel carved into the previous thing rock. That's right, yes. And you do actually see in places that you can see them to the left of the centre, there are layers in the walls of the channel. And they are old lava flows, which this flow had cut through. So you'd have this... By the way, the calculations we've done on these things, the actual flowing lava was typically between five and ten yards deeper. So by the time it's eroded a hundred-yard deep channel, it may feel a little strange. You've got a five-yard deep flow in the bottom of a hundred-yard deep channel still merrily wearing away the floor and carrying it away. And this has gone on for months. Presumably, it was the models, such as the ones that you develop, that really helped people understand this, because this mission was in 1971, I think. Right. And at the time we didn't have any real knowledge of... No, we had the beginnings of the suggestion that it might be lava that was involved, but no idea of the numbers involved. The length of time the flows would have gone on for, what volumes of lava must have been erupted to explain these features. So let's go back a little bit to who cares about all of this. Let's sort of say, well, OK, we've had astronauts go to the moon to look at this lava channel, but trying to bring it closer to home, are there relevant things which we can look as back in the geologic record? Do we see this kind of thing on Earth? We do. Quite rarely, because you do need... Remember, I said that lunar lavas tended to be hotter than what we typically have on the Earth now. But in the Earth's distant past, we did have much hotter lavas erupted. And there's every indication that channels of this kind were created on the Earth. They're not terribly well preserved, but they are preserved in this sense that people have discovered deposits of minerals, of ores, and particularly nickel sulfide. And when these were discovered... Which is valuable, right? Which is valuable, yeah, it's an important source of nickel. And when these were discovered and people started to mine them and cut mine shafts into them and work out the shape of the deposit, they found that these things extended sort of in one direction for a great distance, miles, and the other direction only for tens of yards, hundreds of yards. And what's more, they tended to not follow a straight line or any of the pre-existing geology, they kind of meandered. And it slowly dawned on people that we're looking at ancient, tenuous channels of this kind on the Earth. And what happened was the hot lava ran over sediments, which were rich in sulfur and metals, absorbed those sediments and mounted them, incorporated them into the flow. Then then eventually the lava stops flowing, it cools and crystallizes. The first thing that crystallizes is nickel sulfide. So you get a concentrated layer of that at the bottom of the channel. So in addition to better understanding the evolution of the solar system or the moon in particular, there might be some economic relevance to the kind of models. Yes, yes, in this case, yeah. There are other aspects of that as well, of course. The presence of the big bodies of magma just below the surface that erupts and form all of these features, themselves have an influence. There are a hot spot on the, I'm thinking now, the Earth, the economic aspect. The Actus Plays is where they encourage circulation of groundwater, the rain falls, sinks in, heated up, it moves around, it dissolves minerals, it reprecipitates them. A lot of the Earth's metal deposits are linked to volcanic centers in an analogous way. Fascinating. So, you know, it does have. We can about a minute left line or so just to wrap up. What do you do next? Are your models complete? Do you need to refine them with field work or super computer or what do you do next? You could argue that models are never absolutely complete. And I think we understand aspects of lava flows pretty well now. The next thing that we need to spend more time on is looking at the products of explosive eruptions, putting material into the Earth's atmosphere. We had a big eruption in Iceland that closed down air traffic over the North Atlantic a few years ago. That was a big eruption, but not as big as they can be. And modeling the way explosive eruptions interact with the atmosphere still has quite a ways to go. OK, and we've had people like Sir Euffasian on the show in the past looking at other parts of the solar system. So presumably when you've completely solved all the problems of lunar volcanism, you can move on to another planet. Absolutely. We have Mars, which does have a small atmosphere. So it's a kind of hybrid between the Earth and the Moon. And people who've watched the show before will know I've done a little bit of Mars work myself. You have indeed. Different gravity field to the Moon or to the Earth as well. So still a fruitful area of research, which hopefully will continue to bring you back to Hawaii. Oh, that would be nice. Excellent. Well, I'm afraid we've run out of time, Lionel. So let me just remind the viewers, you have been watching Think Tech Hawaii Research in Manau. I've been your host, Pete McGinnis-Mark, and my guest today has been Professor Lionel Wilson, who's an emeritus professor from Lancaster University in England, as well as being an affiliate faculty member at UH Manau. So thank you for watching. Please join us again next week at 1 o'clock on Monday for another episode of Think Tech Hawaii. Goodbye for now.