The volcano seismologist
Mel Rodgers is a volcanologist who studies the earthquakes generated by volcanoes, in order to predict potential eruptions better. Mel's work requires her to spend a lot of time in close proximity to volatile, active volcanoes – even sacrificing her favorite sweater to collect a sample of rock from a lava flow. Can't handle the heat? Get out of the volcano... and listen to Mel's story in this podcast.
Many thanks to the hospitality of The Fly Bar Tampa.
And many more thanks to the talented and handsome Mathew Halpern for the music featured in this podcast. You can listen to more of his music on SoundCloud as Cole Mathews and as himself, Mathew Halpern. You can follow Mathew on Twitter as @MathewHalpern.
Episode transcript
Parmvir: Hello audience. Thanks for tuning back into our podcast. So today we've had a change of venue and rather than being at the new world brewery, we're currently at the fly bar. And my guest this evening is a very lovely lady called Mel Rogers. Hey Mel, how are you doing?
Mel: Hi very well.
Parmvir: Mel has been recently doctored. So it's now Dr Mel Rogers. Congratulations on getting your PhD.
Mel: Thank you very much. Yeah, it's a good feeling
Parmvir: on that subject. I know a lot of people when they hear the word doctor, they instantly think of medical doctor. And so we kind of have to explain ourselves as PhD's. So can you just tell us a little bit about what your PhD entailed.
Mel: So my PhD, I work on volcano seismology. And so what that entails is a combination of field research, a combination of lab work and analysis, and then a lot of interpretation that goes on, but the American PhDs are actually a little bit different to UK PhDs and they're generally a little bit longer. You generally actually take classes, unlike the UK system.
And you also often teach. So part of responsibilities is either as a teaching assistant or you can sometimes take classes, actually teach, full on introductory geology course classes. So they're a little bit different to UK ones.
Parmvir: So basically as PhDs we're automatically launched into the world of research and we basically do what we're going to do from there on,
Mel: yeah.
We very much, as soon as you arrive, it's "right, figure out what it is you're going to do". and I was lucky in that when I came to the, to USF, I already had a very good advisor who I wanted to work with and we already had a project planned. So. I think a lot of people who do PhDs in the US sort of turn up to grad school and then sort of try and find a project.
Whereas I came in with a very specific, we are working on this volcano doing this, right go. And, right from the outset, I was very, it was very much left up to me to kind of guide my entire PhD.
Parmvir: Very cool. So I know that volcanologists study volcanoes and I know that seismologists study earthquakes. So as a volcano seismologist, what it says on the tin?
Mel: It is, and it's, it's funny, we inhabit this kind of strange space between volcanologists and seismologists in that we actually study the earthquakes that are generated by volcanoes. So all an earthquake is really is a shaking of the ground. And most people, when they think of an earthquake, think of these big tectonic earthquakes, so massive faults that are, that are slipping. But volcanoes because there's a lot of stresses involved in a volcano.
There's a lot of magma that's moving. They, they break rocks. They generate signals that actually move the ground. So by studying those, we can officially use them to better understand the processes that are happening inside the volcano.
Parmvir: And you have a particular volcano that you go to on a regular basis.
Tell us a bit more about that.
Mel: I do. I work on a volcano in Nicaragua. It's called Telica. And it's, it's a very interesting volcano because, often before a volcanic eruption, you, you see an increase in volcanic earthquakes. And usually that's seen as a sign of impending eruption. It's usually one of the signals for what we look for is this volcano going to erupt.
But when they installed the first seismometer at Telica in 1993, the seismicity was so high that they thought is this about to erupt? But it turns out that that's, it's kind of normal behavior. So it's a little bit like a volcano that cries wolf the whole time. The problem is if this is normal behavior, what does it do before it erupts?
And that's the problem that I've been trying to solve.
Parmvir: And so what have you found as far as that goes.
Mel: So actually we were lucky enough. We installed a network of seismometers on Telica in 2010. And Telica was kind enough to erupt for us in 2011. So we were able to really study what happened before the eruption.
And what we've, what we've noticed is that instead of a, sort of an increase in seismicity before an eruption Telica actually switches off. So seismicity drops it actually the whole system kind of seals, if you will, and then we see the eruption happening. So it kind of does everything a bit backwards
Parmvir: As part of your research, do you go and speak to the locals at all?
Are there people that live nearby?
Mel: There's people who live very, very close to the actual active events. There's a, there's a farm there's sort of the end of the road, where generally where we parked the trucks before we start the hike. So there's the family who live up there and there's a lot of farms who live, who very much on the flanks of the volcano.
And they're a very good resource for asking, so what's the volcano been up to because they can often tell us, yeah, it's been gas de gassing recently, or we saw an explosion yesterday. And so we, yeah, we do talk to locals a lot and of course they always want to know. So when's it going to erupt and yeah, of course, that's not an easy question to answer.
Parmvir: Yeah. I can believe that. But do you ever wonder why people continue to live in these areas?
Mel: No. it's, it's, it's one of these problems that exists around volcanic regions. And it's something that I think a lot of people who don't work in around volcanoes don't often understand that a lot of people have no choice.
They live on a volcano because that's the farm that they inherited or that's where they live. And many of these communities are, they can't afford to, to just up and move and live somewhere else. But the other reason a lot of people live on volcanoes is the ground is exceptionally fertile. So the crops that you grow in volcanic regions, it's immensely productive.
So a lot of these people don't even want to leave. They absolutely don't want to up and leave even if they have the funds and the availability to do that. It's too nice of an area for that.
Parmvir: You've also been to a conference. Not too long ago...
Mel: The conferences are fantastic opportunities to, to meet a lot of the people you've only ever read their work.
And also to sort of talk about your ideas and get feedback. So I presented a poster at the conference I was at in Japan. And you often get a lot of people coming up to your poster and you're able to explain your research, to some of the sort of eminent names in the field, and you get some fantastic feedback from them.
And you also, you form a lot of very important collaborations at conferences. So future work with people is often formed at a conference.
Parmvir: Okay. So before we go on, how did volcanoes form in the first place?
Mel: Whew. Okay. there are many ways, so there are many different ways the volcano can come and come about.
So you can't really discuss volcanoes without talking a little bit about plate tectonics. So the surface of the earth is split up into these chunks of plates, basically chunks of crust and a little bit of mantle, that move around on the surface of the earth. And most volcanoes are formed at the boundaries of those plates.
There's two sort of main ways that we see volcanoes forming. The first, and this is probably the most common type of eruptions that we see on land have formed something called a subduction zone. So what happens at a subduction zone is that you have continental plate. So continental, lithosphere, and oceanic lithosphere, which is denser and rides a little bit lower than the continental crust as they collide the oceanic crust is pushed down: it's subducts beneath the continental crust. And in doing that, it takes down sediment that's entrained in that top of that plate. And just like in a winter's day, not that anyone here in Tampa would know this, but on a winter day, if you add salts to the ice, you're going to melt it. So a little bit like that. If you add water to the hot mantle rocks beneath the continental crust, you'll melt them. That generates melt molten rock, which then wants to rise. So that rises through the crust and erupts as a volcano.
The other type of, volcanoes that we see are something called a mid-ocean Ridge. So this is where two oceanic plates they're actually pulling they're, actually moving apart. And in the moving apart, this sort of just rifting process, you get an upwelling of material and you get volcanoes formed in that way.
The third type of volcano that we see is a volcano that forms at a hotspot. So you have a sort of a localized upwelling of a plume of very hot mantle material. And as it rises, it generates melt and that melts then erupts, for example, Hawaii and possibly Yellowstone are examples of those.
Parmvir: So your volcano in Nicaragua, which one of those categories does it fall into
Mel: The volcano that I study is a part of a seduction zone.
So in this area, the, the Cocos plate is actually subducting beneath the Caribbean plate. And that's, what's forming the magma that we see then at the surface at Telica, so it's a subduction zone volcano.
Parmvir: Okay. Very cool. I'm going to start off with, the infuriating questions from Philip first.
So this is about the, the Icelandic volcano, which I refuse to pronounce, but if people were here, they would see that Mel has this on her t-shirt right now, how do you say it?
Mel: So I actually cornered a poor girl in a bar in Reykjavik and bought her beer until she taught me how to pronounce this volcano.
And it's pronounced Eyjafjallajökull.
Parmvir: Try saying that three times fast. So the question was that for anybody who remembers back to a few years ago, this thing erupted and caused huge amounts of chaos. So how common are volcano volcanic events with global consequences?
Mel: So the consequences of that eruption was that aircraft were grounded across pretty much all of Western Europe for, I think about five to six days. And a lot of people think, Oh, it must've been this massive eruption that stopped our travel for a long time. But the 2010 eruption of Eyjafjallajökull was a really, really small eruption. And there was a few reasons. why Eyjafjallajökull was so devastating to air traffic, it was a combination of the wind direction. It was a combination of the fact that this volcano had erupted under a glacier, which fragmented the ash into much finer particles than if it had been a sub-aerial rather than a subglacial eruption.
The fact is that even small eruptions, like this can have massive consequences, but having said that there are larger eruptions that have occurred in our lifetimes that have had next to no massive global consequences.
Parmvir: Actually this question we've heard from a couple of people and one of them includes Steph from Australia and she asks is Naples likely to be destroyed in our lifetime because several people have heard these stories, saying that Neapolitans should devise escape strategies without delay as Vesuvius is due for its largest eruption yet. And of course, by Neapolitans, we're talking about the ones in Italy. So the ones in Florida, I think you're fairly safe from volcanic eruptions.
Mel: Well, you can never say that a volcano like that, like Vesuvius is not going to erupt in our lifetime because yes, it could. I think it's unlikely to erupt, you know tomorrow, because I think we would see signs of that, but you know, we could be entirely wrong, but yeah, it's possible. Yes. But there are many, many cities like Naples that exist very, very close to very dangerous volcanic regions.
Mexico city is another fantastic example. It's right next to a very active volcano. And it's also in a volcanic field of its own. Manila, there's another example of a big city, that's very close to volcanic regions. And this is the problem with a lot of big cities is they're extremely close to very large and very dangerous volcanoes.
Parmvir: So are there potentially people who had planning just exit strategies for people?
Mel: Absolutely. Yeah, absolutely. When you're talking about a volcano, you don't just have to think about the volcano itself and what's the size of the eruption, but you have to think about what is the population there, what's the population at risk. So this is the difference between risk and a hazard. So risk involves looking at what are the effects and the consequences for people around that volcano. And this is why cities like Naples have such a high risk.
Parmvir: So how does a volcano die? Can a volcano die?
Mel: Absolutely. Absolutely. There are all kinds of dead volcanoes all over the place.
Edinburgh, for example, is Arthur's Seat is a volcanic plug. Devils was it devil's tower in Wyoming is the inside of a volcano that's been eroded and we see the actual internal organs as such of that volcano, so absolutely volcanoes die. And that's a very interesting question because we don't ever really know that a volcano has died until it doesn't erupt anymore.
So we have a lot of volcanoes that are active, but haven't erupted in a long time. And this is a very interesting definition because what's the definition of an active volcano? And that's not something that's entirely clear because a volcano may have erupted 2000 years ago. It's certainly not dead. It may be, it may never erupt again, but we're not going to know that until a very, very long time. And one, one of the ways that volcano would, would die is if its source of magma has basically switched off. So magma is what's basically driving most, not all, but most volcanic eruptions are driven by inputs of fresh new molten rock, basically. And if that supply is switched off so for example, if the plates, we talked about plate tectonics just a second ago, and if those, if those plate boundaries are moved, if they shift, which they do, they move over time and you effectively remove, remove your source of magma that's one way that a volcano may, may die. If the source actually moves quite often, you can get a sort of a leapfrog and a new volcano will form somewhere else. So in that way, you get the sort of evolution of, of a volcano. For example, if you had a subduction zone that was your source, subduction, the melts is generally, the melts generally formed at a very specific depth on the, on the subducting plate. And so if that plate is moving, which it does, it, it sort of falls back at rolls back that then is going to move. And then the overlaying plate, you're going to see a migration of that volcano. And you actually see this in volcanic chains that you often see along the line of volcanoes that are getting progressively younger towards the trench.
Parmvir: So would that be, is Costa Rica an example of that kind of volcanic chain or
Mel: It does, there is a subduction zone, is it Costa Rica? It's actually the same volcanic chain as the volcano that I study in Nicaragua. So it's the central American volcanic front, and that's it's happening there, that volcanoes are all moving, but it's a very, it's a very topical question of, you know, how does a volcano switch off?
Parmvir: This is more of a social question than a science question, but are there popular volcanoes that all researchers would like to study and do people get preferential treatment as to which ones they get to study,
Mel: So I think you could get a different answer from every single person you talk to. There are some volcanoes that are consistently erupting and we kind of call these our laboratory volcanoes.
For example, Stromboli in Italy is just constantly erupting. And that's a fantastic one. If you want to put out instruments and test something, but it's very well studied and we know a lot about it. Of course, we don't know everything about it. But I don't think every single person has, the the same volcano because every researcher in volcanology has a different interest. So one volcano may be of interest to one person and a different volcano for entirely different reason is of interest to another. But as for who gets to work on volcanoes, that can also be quite a political challenge because most volcano observatories are run by local government organizations and generally to get to work with them you need some kind of agreement, some kind of understanding of what you're going to do with that data. So that can be quite tricky and often makes or breaks, proposals and funding. And it also comes down to money. Can you get funding to do your research?
Parmvir: Do you have a dream volcano you'd like to work on?
Mel: Ooh, gosh, there's a lot. I'd actually quite like to work on and I may hopefully in the future get to work on Tungurahua in Ecuador. It's actually erupting right now and it produces some of the loudest volcanic explosions that have been recorded anywhere on the planet. And we can actually, we've actually listened to the, the acoustic sound that a volcano makes when it explodes. And this is actually one of the loudest volcanoes in the world. So that's pretty cool.
Parmvir: When you're adding your, what did you call them? The meters for measuring seismometers. How do you do that?
Mel: Ooh, many, many ways. So we, our network, we, we built concrete bunkers, so these little concrete huts, some of them existed already, we built two of these things. And we install the seismometer. We put it directly on the, the concrete floor of these huts. And then we have solar panels on the roof of these huts, we have battery packs inside, we install it, close the door, walk away.
Parmvir: So these huts are built around the base of the volcano?
Mel: These are built at varying distances from the volcano and at varying angles so we have complete coverage of the volcano, but if you're not lucky enough to have these concrete huts, and if you're only deploying temporary, deployment or if you're somewhere where security is not an issue, then what a lot of people do is they will dig a hole in the ground. They'll pack down the ground. You'll place the seismometer directly into that hole. You'll generally then get a bucket, turn it upside down, put it over the seismometer and then fill in all the soil and put your solar panel on top.
Parmvir: Okay. So the slightly more low tech option.
Mel: Yeah. And not as secure because people come along and steal your solar panels or your batteries, or your instruments.
Parmvir: So how important do you think past and future record keeping will be for seismic activity in this era of fracking?
Mel: So for those who don't know, fracking is a process that's, oil and gas companies are using to extract hydrocarbons from, from reservoirs, where they actually fracture the rock, to extract more oil or more gas. And this. It's a kind of interesting question because we have seen increase in seismicity over the last decade in America, but this isn't necessarily due to fracking and we don't really know why this is happening. It could also, it could be that we're seeing an improvement in monitoring. So the more seismometers you put out the better quality of instrumentation, the more earthquakes you're going to record, it's like having a, you know, a better microphone, you're going to hear more noise. The other thing that could be contributing to this is that there's been a massive, broadband array of seismometers, I think a few hundred have been installed, and it's been slowly working its way across the US, it's actually in Florida right now. And it's a massive project consisting of hundreds of seismometers. And those of course is an improved network. It could also be that there's an increase in seismicity. We don't know. And it's not a question that has actually been answered yet.
Parmvir: Well, thank you very much for coming to speak to us. It's been absolutely enlightening. For people who don't know Mel having finished her studies is going to leave us to the prestigious Heights of Oxford in the UK.
So the very best of luck.
Mel: Thank you very much. It was a pleasure to talk to you and fascinating questions.
[Musical outro]
Mel: In 2004 I was working in Mexico, I was working on the Volcán de Colima and when I first turned up there Colima had been exploding sort of every day, more or less like clockwork, but the day I showed up, it stopped exploding. I was really gutted because, I really want to see this thing explode.
The reason it had stopped exploding is we found out a few weeks later, was that a lava dome had formed in the crater of this volcano effectively plugging, and stopping this explosion.
So what do I mean by a lava dome? Because I think most people, when I talk about lava, imagine sort of running rivers of molten rock a bit like Mount Doom from Lord of the rings. But this volcano erupted very sticky kind of lava. It's almost like toothpaste. So it'd actually formed this sort of plug in the top. And when we realized that it was actually now extruding lava, rather than just exploding gas and ash, this was really exciting.
So we thought, fantastic. Let's go pack our bags off to the field we went. And we wanted to try and get a sample of this lava dome. Blocks of this lava, dome were breaking off and rolling down the sides of the volcano. So we waited, to try and catch, let's see if a big enough block broke off such that we could actually get a sample of it. Eventually one, like a block the size of a house kind of broke off barreled its way down the side of the volcano. We watched it and we thought, yeah, that's low enough for us to go in and take a sample.
So ran out of our camp, got up to the volcano, got to the base of the volcano and the block that had made it down. It was about the size of a small car. And so my colleague kept a watch out for any other boulders coming down. I ran up to the boulder and it was fantastic. It had this huge crack through the middle. It was still glowing red inside. It was just fantastic.
And of course, in the excitement of let's go get this boulder. I'd forgotten to bring my rock hammer. I'd forgotten to bring my heat proof gloves. So I just started tearing chunks of this thing off with my hands. I realized it was a bit hot. And then I pulled out my plastic sample bag. Put my sample in, of course it melted straight through and landed on my feet. So I took off my sweater, wrapped the rocks in that, and then we, we legged it back to camp.
Parmvir and Mel both saying “Magma” in the style of Dr. Evil from Austin Powers, then making “ooooo-eeeeee-ooooo” sounds like a voice warm up exercise.
Mel: That's a bit weird. Isn't it?