 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-Marc, and every Monday at this time we present some of the active researchers being conducted at the University of Hawaii. We bring in graduate students, we bring in research faculty members, as well as some of the guests coming to Hawaii, specifically to do research here in the islands. One of my guests today is one of the graduate students, Erin Fitch, is a graduate student in the Hawaii Institute of Geophysics and Planetology at UH Manoa. So welcome, Erin. Thank you for having me, Pete. Our show today is all about when hot lava interacts with water, right? Yes. That's a very interesting topic for a student to be involved in. Can you tell me a little bit about it as an introduction? Yeah, so it is a very interesting topic and very relevant to Hawaii. I have been so interested in this topic that I have spent the past five years studying it in my PhD. So when lava interacts with water, like here in Hawaii, we have lava entering the ocean, it can interact explosively, and it can be a potential hazard and important for the whole field of volcanology in general to understand better. Interesting. We've had several other people as guests on the show talking about various aspects of volcano ice interaction and that sort of thing, but this is clearly one of the major topics at UH Manoa. In fact, we've got, well, volcanologists here. So let's take a look at the first slide, if we may, and I think this will give our viewers a little bit better understanding of what kinds of products or the landforms which come up. So let's look at this, and this is presumably not of Hawaii, right? No, this isn't Iceland. This is outside of the capital of Iceland, Reykjavik. It's a cone built from repeated lava water explosions as a lava flow entered a lake basin, and it's part of what's called the Riflar Rulis Cone Group. So this is just one of many cones. And you can see a city in the background. Is that Reykjavik? That's Reykjavik. Yeah. That's Reykjavik. And you can see in the background the sort of the brownish cone. Yeah. How high is that? Oh, that is about 14 meters high. About 14 meters, or about 40 feet or something like that. Yeah. Well, of course, we're in Hawaii, and that you go to Iceland? Yeah. I mean, this is interesting from, you know, so you go halfway around the world to study a landform that we have here in Hawaii. It's not just a subsidized vacation. Uh-huh. So the reason why we wanted to go to Iceland to study this particular cone group is because the rootless cones that form from lava water explosions in Hawaii tend to form near the coastline when lava enters the ocean. And it's not the only formation environment that you can have lava water explosions. So in order to adequately study this process fully, we needed to go to a place where lava water explosions were initiated in a different kind of environment. So in Iceland, many of the rootless cones form when lava enters a lake basin. So this is a very specific environment to Iceland for the most part. And you know, you can build these cone fields of hundreds of rootless cones. Okay. And obviously here in Hawaii, we don't have these lake beds or anything like that. So that's why you would go to Iceland. Is that the only place where you could find these sort of landforms? It's not the only place. But there are far more rootless cones in Iceland and Hawaii than anywhere else on the planet. Really? Yes. They're two very special locations for this process. And you and I know that Iceland has the same kind of rock chemistry. Yes. But what we're seeing is a different type of landscape produced by the same rock types that we have here in Hawaii. Exactly. So we can study, we have a study site on the Big Island as well. And so because it is the same rock chemistry, we can directly compare those two study sites. Right. Okay. Let's take a look at the second slide because I think we'll get a much better feel. We're looking at the side of one of these cones, correct? Yes. Yes. All right. And again, this is about 40 feet high. Yeah. Something like that. So explain to the viewers what it is we're looking at. Yeah. So we have three different deposits built from repeated explosive events. So the very thick, very hard-looking layer at the very top was molten material that then continued to merge, which was still hot when it landed, and flow, we call that a reamorphic flow. And you can see another layer that's similar, a little ways below about halfway through the cone. Clean these layers and below that middle layer are just separate deposits of these individual explosions. So a cone can be built from 10 to hundreds of explosions depending on the cone size. And the material at the bottom part of this image, it looks as if it's layers, so that's individual explosive events. Yes. And are they any different from, say, the cinder cones which we have here in Hawaii or would you be able to recognize the differences? Yes. There are distinct differences between the ejecta, the material that comes out of these explosions, and tephra that builds cinder cones for sure. So one of the main differences is the amount of gas bubbles inside of the ejecta is much smaller for rootless cones than cinder cones. But in general, we can see that rootless cones are associated with the lava flow, whereas a cinder cone, it's also much bigger and it's not usually associated with a lava flow. So if you went and dug a section through diamond head, not that we're suggesting that of course, or some of the cones on the monocare on the big eye, you would not see that same kind of layering or in detail a geologist like yourself, she would find something that would say this has to have been in action with water producing the explosion. We would still see layers, but they have different characteristics that I don't know if we have time to go into detail, but definitely there are some distinct differences. But this is what you would do a PhD on, the subtle differences, right? Yes, yes. There are characteristics of these sorts of eruptions which you can see. Yeah, and the work that we do, we definitely set aside part of our publications to compare rootless cones with magnetic eruptions. All right, so we're going to give you a quiz now because I think your third slide will actually show one of these examples up close and personal. So here we're seeing whole layers of rock. What sort of scale do we have here? Oh, this is probably about three feet of section. Okay. Yeah, and you can see this is a very beautiful example of that orange color is actually lake sediment that is being incorporated into this ejecta, whereas the gray is mostly fragments of lava. And what as a student, do you actually go and study, do you measure the shapes or the sizes or the density or? Everything. Everything. So we go in and we delineate the layering and then we take representative samples sometimes up to a ton of material. We will sieve down to different sizes and that gives us a distribution of the different size material that's in each bed and that can tell us about the explosivity of that interaction. And then I also go in and I look at the shapes of the ejecta in order to try to understand the state of the lava at the time it fragmented, which can tell us about not only the lava flow characteristics, but help us reconstruct the energetics of these explosions. So let's just back up a bit. You look at the size and that's what you're sieving just to find the coarse material from the find. Yes. Do you do this in just one locality or? No, we sieve the really big stuff out in the field, which can take weeks of manual labor and then we take a small portion of the finer material and bring it back to the lab and sieve that as well in fine detail, which can also take quite a while. And presumably the coarse material lands closer to the vent, depending on how explosive they look. So it's important for us to choose the right site to samples that can take some time as well. And then the shapes, what can you learn from the shapes? So because it's a lava flow that's interacting with water explosively and lava flows have a molten core and a solid crust, those different states of lava are going to fragment differently. The amount of energy it takes to fragment material of different states is going to, we're going to need to constrain that in order to understand the energetics of these explosions. So I go in and I look at a representative set of samples from each of these deposits and try to determine what was molten at the time it fragmented from the core and what was from the crust of solid at the time of fragmentation. So do we have the same kind of feature with lava flows of different thicknesses, or would a thin lava flow be easy to fragment compared to a thick one? That's a good point. A thin lava flow may be more easy to fragment, but it also wouldn't require as much pressure buildup. These are ultimately steam explosions, water is vaporizing, pressurized, and ultimately when that pressure is released, it can fragment the material that's lava around it. And presumably a thinner lava flow would have a lower heat content. Exactly, that too. So it's less likely to... So there's perfect balance of, you know, amount of lava and amount of water that needs to be met to create a really, you know, genuinely large explosion. So that actually is what we're doing on the Big Island. We have a wonderful study site where we see some very energetic explosions and that's how it happens. I think we'll get to that in a couple of slides, but to put you on the spot again, let's look at the next slide because this is another one of your field photographs. I presume that the knife there isn't a six foot long light saber, so that's giving us the scale. What do you learn on this image, which is another vertical section that you did not understand from the previous image? So in this image we see very distinct differences in the size of the ejecta in these deposits. So you can see that where the knife is is a very coarse-grained deposit, very large pieces that were fragmented and make up that deposit, whereas right underneath it is very fine grained. So the fine grained deposit was the result of a much more high energy explosion than the one above it. And the high energy would have distributed this material over a much larger area, so we don't know the context here, but maybe this is further away from the explosions? Yeah, potentially. Potentially. Something like that. And we're seeing at the extreme top right what looks to me like some of the original lava flows. Potentially. It doesn't destroy the entire lava flow. Maybe there's a sequence of events where the first flow explodes. Absolutely. You can have lava flows burying this ejecta and then more explosive activity creating more ejecta that lands on top of the flow. You can get this sort of interlayering sometimes of lava flows and this lava water explosion. Now is this a common occurrence in Iceland? Do you say that? I would say that it is a distinct feature that has been seen to be associated with Icelandic volcanism because of the environmental conditions in which lava can flow into. Iceland has a lot of sort of low lying marshy areas and lakes, which we don't really have in the same abundance in Hawaii. And in the first image we saw that these cones were actually quite close to Reykjavik. They must be a natural hazard, much more so than this phenomenon here in Hawaii. Yeah, they can be. So one of the most recent eruptions in Iceland, the Barthabunga eruption, generated massive lava flows and some of them entered a stream basin and there was some concern over whether or not this would initiate lava water explosion. So it's important for us to understand this process from a hazard standpoint. Right. I'm getting into the break, Erin, but I think we should pick up on this sort of hazard aspect of your work in the second half of the show. So let me just remind our viewers, you are watching Think Tech Hawaii research in Manoa. I'm your host, Pete McGinnis-Marc, and my guest today is Erin Fitch, who is a graduate student in the Hawaii Institute of Geophysics at Yorich Manoa, and we'll be back in about a minute. So see you then. This is Think Tech Hawaii, raising public awareness. Hello, my name is Stephanie Mack, and I'm co-host of Hawaii Food and Farmers Series. Think Tech is important to our community because it provides a platform for all the important issues in our society. For the first time, Think Tech Hawaii is participating in an online web-based fundraising campaign to raise $40,000. Give thanks to Think Tech. We'll run only during the month of November, and you can help. Please donate what you can so that Think Tech Hawaii can continue to raise public awareness and promote civic engagement through free programming, like mine. I've already made my donation, and I look forward to yours. Please send in your tax-deductible contribution by going to this website. Thanks for ThinkTech.Causebox.com. On behalf of the community enriched by Think Tech Hawaii's 30-plus weekly shows, thank you for your generosity. And welcome back to Think Tech Hawaii's research in Manoa. I'm your host, Pete McGinnis-Marc. My guest today is Erin Fitch, who is a graduate student in the Hawaii Institute of Geophysics and Planetology. Now, Erin, before the break, we were talking a little bit about the volcanology, but we then got into the point that this kind of eruption might actually be quite dangerous. It's fortunate that we don't have many examples here in Hawaii, but should individuals in Hawaii be concerned about this type of eruption? Yeah, they definitely should be aware and respectful of the boundaries that the National Park and the Hawaii Volcano Observatory puts in place for their safety when lava enters the ocean. Right, because we've got ongoing lava flows from the Pu'u O'Vent, which are entering the ocean, and presumably that's the prime example of where we might be seeing this sort of thing. I've been out there myself, and it's a beautiful site to go see active lava flows and lava entering the ocean. And sometimes you can see lava water explosions, but again, it's important to be careful of those boundaries. Yeah, and to warn the viewers, you've brought along another image or two of Hawaii examples and the kinds of landscapes which could be doing. So here we've got a few, tell us where this is and what it is we're looking at. This is the south flank of Mauna Loa, south of Ocean View Estates. So many of you guys are probably familiar with this area. There's a road called Road to the Sea, it's a great fishing spot, but it's also the home of the Manuka Natural Area Reserve. And within the area reserve are these very large cones from high energy lava water explosions. So that hill on the right hand side in this image, that's one of these cones that's been produced as the lava entered the ocean and presumably Mauna Loa as it produces bigger lava flows. The lava flows came from Mauna Loa. And the lava flow itself is this dark area, this wobbly-like area. Yes, that's correct. And I think we've got a second view of the same general area. And Erin, is this one of your field areas? Yes. Yeah. No, let's go back. Not that side. We should have a different side. Well, we'll hold off on the next one. But these kinds of eruptions are rare in Hawaii, but presumably they would primarily occur at the coastline. Yes, they would occur at the coastline because Hawaii doesn't really have league areas for lava to enter. Hawaii can produce quite energetic lava water explosions because the lava flows can sometimes enter the ocean at high volume and high speeds. And this can initiate very energetic mixing of lava and water. So you go into the field quite often, but you've been to Iceland. It must be fascinating. The logistics of going from Hawaii to Iceland, what's it like to work in the field in Iceland? That's wonderful. Iceland's a really beautiful place. One of the differences between Hawaii and Iceland is Iceland doesn't have the same kind of vegetative cover that Hawaii has. Of course, on the coastal plain, there are these expansive lava flow fields in Hawaii where you get to see all the geologic materials right out in front of you. In Iceland, it's even more stark, and that makes for this really beautiful landscape to work in. But logistically, it's much more difficult. It's more expensive to get there. The camp? Can you drive a vehicle to your site? We're fortunate that the two main study sites in Iceland, where rootless cones exist and have been studied in detail, have been either close to Reykjavik, so we could stay in Reykjavik and drive out, or have been close to cabins that have been set up for sheepherders historically. So it's camping in a way. I have camped while doing field work in Iceland before because it's sometimes nice to get out there and rough it a bit. And then how long are you in the field because Iceland's cold during the winter months, for example? We really only get this short window in the summer to do work in Iceland. So when you do work out there, it's usually all one big go. So when I went to Iceland, it was for about eight weeks. Really? Yeah. And that's obviously in our summer time? Yes. Yeah. June or July or something like that? Yes. It was in July, maybe early August, early August. And it's a wonderful time of year to work and still can be quite cold and drizzly, but it's important that all the work gets done and that one go. So it is a little bit more stressful because you want to make sure you get everything you need. Here in Hawaii, I'm on Oahu, study sites on Big Island. It's an hour flight. It still takes some logistical effort to get out there. The Manukannar is all off-road and very difficult off-roading. So it still takes an effort. And when I'm doing fieldwork out there, I do live in the field for usually a week or two at a time, but I do have the benefit of collecting samples and then bringing them back to the lab, analyzing them, and having that inform my next series of fieldwork, which is one of the benefits of doing work in Hawaii. Do you do computer analysis of the data or is it mainly the measurements which you're making and you're plotting out maps? It depends on our goal. There is some computer analysis of the data. I don't know if you really want to hear about that. It's quite boring, but all part of the job. It's a lot of data to wrangle. I make lots of observations in the lab and it can take months. Getting all of that data together into a package and a story, being able to understand what's happening can definitely take some time. A lot of discussions with other scientists for sure. Are there a lot of people working on this kind of topic or is Hawaii one of the rare places? Are more now than when I started. So I think it's been really nice to be part of that wave. I feel like here in Hawaii we have the unique advantage of being right next to some of these wonderful studies. You're in a hot field in other words. We're at the crest of the wave. Great. Well, and as our viewers will have seen with the slight preview here, I understand that some of your work isn't just relevant for volcanic hazards here on Earth, right? If we can go to the next slide, the one we've already seen, we've had a number of guests come on the show talking about volcanism on the other planet. So the next slide will show us, I hope, that we'll actually get some examples of the same kind of features that you study in Iceland, but on planet Mars. So here we go. And the scale bar down in the bottom right, 250 meters, so 700 feet. What direction is the sun shining from here? We're looking at some very odd objects. It looks as if it's from the right-hand side. So these are cones? These are cones. So sometimes it's hard for your eyes to make out in Mars imagery a cone shape. Sometimes it can almost look like a crater. So sometimes you have to give it a moment for your eyes to adjust. But these are cones. This is a series of cones sitting on top of what I believe is a flood lava. And it likely covered the landscape fairly quickly. And these cones are associated with that lava interacting with water in the Mars regolith. So we could extrapolate the fact that you see the same kind of features on another planet. Presumably Mars has a lower gravity, so these form more easily? You can produce larger cones with less explosive initial explosive energy. And the actual thickness of the lava flows could be perhaps a little bit thicker or something like that. Probably thicker, yeah. That's a good point. Yeah. And these look to be quite fresh cones. So presumably we've had liquid water close to the surface of Mars. Or can you use the occurrence of these cones to? That's still an ongoing area of research, for sure. Trying to understand how long water can stay available at the surface or subsurface of Mars and how much was available in the past. But we at least know that there is ice on the surface of Mars and within the surface substrate. And that when heated, this can volatilize or turn into a gas form. And if you have a gas form, you can potentially have an explosion. Does it make any difference the type of landform you see if you have ice in the soil versus liquid water? Not really. It really doesn't. Because the lava is so hot compared to the water or ice that melting of the ice into water, it's not that much of a difference in temperature. So you can't use the cones as a diagnostic landform. It has to be water close to the surface. Now this is a really detailed subject for your PhD. How did you get interested in this? What did you do as an undergraduate? Or why did you come to Hawaii? Well, I did geology as an undergraduate. I was always interested in applied math as well. So I did a minor in mathematics with the hope that I would end up doing something like this. But I actually got interested in rootless cones quite a while back and was interested in my current advisor's past work. When I went to northern Mexico on a field trip, and there's a very large volcanic field called the Pena Cates Volcanic Field, and there's lots of features in that field where volcanic processes have interacted with water. Sometimes groundwater. But what I was standing on was the side of a cinder cone looking down at lava flows and the instructor of the field course said, look, this was a lake basin. There was a lake here in the past, and it's since dried up with climate change. And this is way past, thousands of years ago. We're not talking recent climate change. But there wasn't a lake there anymore and there was not going to be a lake there next year or any time in the future. But yet, at the edge of that lake where the lava flow had entered the lake, you could see these tiny little cones. And those were rootless cones. And that was the first time I still have these old polaroid photos, these rootless cones. And I think for me, it was fascinating because it was like having a time machine. Being able to see that in the past there was water. And there's not water now, but here's this construct that can help us understand. I started reading some of the papers that Sarah Fagin, who's also... who has been on the show in the past, yes. Had written. And I was very fascinated with how we could see something on Earth that we could see on Mars. Even at that time, they'd identified rootless cones on Mars. And this was really fascinated by the process. And the more I read, the more I wanted to get involved and contacted her. And she had some fun day. And then, we all hope you graduate next summer. Yes. What do you do after that? Is it natural hazards? Are you doing planetary work? Are you doing more fieldwork in Iceland? Well, there's always more fieldwork. I'll always be doing fieldwork until I can't get in the field anymore. But there's always more work to be done. You never finish, you know, on a subject during your PhD. So, I've done a lot of fieldwork, a lot of laboratory analysis. And I'm starting to do numerical modeling to try to understand the energetics of these explosions. And there's more work to be done in the future. It sounds as if you've got a project for your postdoctoral fellowships there. Yes. Yes, I do. I'd like to continue this work. Sounds fascinating work. Unfortunately, we're getting towards the end of the show. So, let me thank you again. Thank you. As the viewers, you have been watching think tech Hawaii research in Manoa. I've been your host, Pete McGinnis-Mark, and my guest today has been Aaron Fitch, who is a graduate student in the Hawaii Institute of Geophysics and Planetology. So, thanks for watching the show. And join us again next Monday at 1 o'clock for another think tech Hawaii research in Manoa. Goodbye for now.