Understanding St. Vincent’s Volcanic Eruption

IRA FLATOW: This is Science Friday. I’m Ira Flatow. Since last Friday, the Caribbean island of St. Vincent has been rocked by eruptions at the La Soufriere volcano. Over the last week, plumes of ash and gas have plagued the island. Flows of debris are destroying whatever is in its path.

The last time this volcano erupted was in 1979. So what’s been happening in St. Vincent and in the volcano? Joining me today to fill us in on the impact of this volcanic event is Dr. Jazmin Scarlett, historical and social volcanologist based in Newcastle-upon-Tyne, England. Welcome, Jazmin, to Science Friday.

JAZMIN SCARLETT: Hello.

IRA FLATOW: Paint us a picture, if you will, of where this volcano is, where on the island of St. Vincent it is, how far from people, all that kind of stuff.

JAZMIN SCARLETT: OK, so La Soufriere is actually part of a chain of volcanic centers on this tiny little island on mainland St. Vincent. So these chain of volcanoes– they are extinct, but they run from south to the north, and La Soufriere is the active volcano in the north on the island. And I essentially describe this island as a small island with a big volcano in it, because La Soufriere dominates pretty much the northern half of the island.

And people live quite close to this volcano. So this volcano can pretty much impact everybody on the island, because it’s just that big.

IRA FLATOW: When a lot of us think of volcanoes, we think of lava. Is there a lava coming from La Soufriere?

JAZMIN SCARLETT: Yeah. So the type of lava is not what you would think it is. So in December, when this eruption started, it was an effusive eruption. And this is basically the quiet oozing out of lava. But compared to, say, Kilauea, for example, in Hawaii, this lava doesn’t travel very far, because it’s very sticky, and it’s very blocky. And it just can’t flow that far.

So what it does instead is it forms a dome. And what happened since December was a new dome was growing alongside the old dome, which happened at the end of the 1979 eruption. So this is the kind of lava that you see. It doesn’t go very far, particularly because of the shape of the volcano, so it can’t actually escape the volcano unless there’s loads and loads and loads of it, but it didn’t actually get to that stage. So it’s not the kind of typical lava that you think it is.

IRA FLATOW: So the dome is sort of a warning that something was going to happen?

JAZMIN SCARLETT: Yes, essentially. But the problem is that we just didn’t know exactly. So this kind of behavior of forming a lava dome and then going into an explosive phase is common for La Soufriere, and actually quite common for volcanoes in the Caribbean.

So for us, we kind of knew something would happen, but we just didn’t know when. So we didn’t know it was going to happen in April. We didn’t know that from the growth of the dome.

IRA FLATOW: Have a lot of people been evacuated?

JAZMIN SCARLETT: Yes, so in the red zone, there’s approximately 20,000 people. So they were evacuated pretty much under 24 hours from the first explosion, which, I have to say, really gave me heart palpitations, because I was like, oh my goodness, this is a very close. But hats off to Seismic Research Center volcanologists for actually calling it, because essentially, they saved thousands of people’s lives.

IRA FLATOW: Has anyone been injured or killed?

JAZMIN SCARLETT: As far as we know, no. But these kind of reports, they can be quite sketchy, because now there is an exclusion zone down to the orange zone of La Soufriere. So only authorized officials can go in there. However, we do know that there has been some people that have stayed behind even though the prime minister and the volcanologists have been trying to encourage them to leave, because it is very dangerous to stay there.

IRA FLATOW: Yeah, no, I’ve heard a lot of people talking about pyroclastic flows that are coming from this volcano. Can you define for us what a pyroclastic flow is?

JAZMIN SCARLETT: Yes. So the new term that volcanologists use are called pyroclastic density currents. But we can still use pyroclastic flows. The French use the term nuée ardente, as well, which translates to “burning avalanches.”

So essentially, they are very hot and very fast ash flows. And particularly for La Soufriere, they are the result of ash column collapse. So essentially, some of the plumes that are being generated, they basically can’t be sustained from the heat of convection, so they collapse.

And these are very dangerous because they can flow up to 300 miles per hour. They can be up to 1,000 degrees Celsius. So very hot and very fast.

And they’re dangerous because, for one thing, we still don’t fully understand how they behave and how they work. But they can be channelized down river valleys. They can blanket flanks of volcanoes. They can travel uphill and surmount topography. They can flow over water, as well. So these things are very, very dangerous. And for La Soufriere, they can pretty much impact the whole kind of area where the volcano is.

IRA FLATOW: What is it made out of? Is it rock? Is it dirt? Is it part of the mountain? What is it composed of?

JAZMIN SCARLETT: It’s a mixture of all of that, so it’s mainly volcanic material that’s in the ash plume coming out of the volcano, but also gases, as well, and any debris that it picks up, as well.

IRA FLATOW: Wow, I didn’t know that. As of this recording, there are explosions at the volcano at least once a day. And it’s been a week now. When will we know that the volcano is done?

JAZMIN SCARLETT: So this is a question I have been getting a lot. And the answer is, we do not know. So for example, the 1812 eruption of La Soufriere went on for six weeks. The 1902 eruption, which the 2021 eruption is being compared to, went on for 10 months. And the 1979 one went on for two weeks. So we honestly do not know.

But what could happen is that it could quiet down for a bit, but then it could actually pick up its momentum and its activity again at a later stage. And that is quite common at La Soufriere, to be energetic in the beginning, be quiet for a little bit, but then also pick back up again. So we really do not know, and that’s why it’s very important to keep monitoring what’s going on at the volcano.

IRA FLATOW: Is the water safe to drink, the air safe to breathe, around there? What are officials saying about that and food and all these other kinds of things that people need to know?

JAZMIN SCARLETT: So with the food, all these crops have been destroyed or, essentially, the vegetation has been stripped of the bark, and that’s to be expected. So foods that naturally grow, and fruits, particularly, that naturally grow, they cannot be eaten and they cannot be marketed. Similar with water– if they’re not being protected, like covered properly or sealed properly, particularly water tanks, they’ll be contaminated. So you would have to at least boil the water before you use it because of the contaminants from within the volcanic ash, because volcanic ash actually has quite a lot of sulfur dioxide and carbon dioxide in it. So it could actually be harmful to your health and to animals’ health as well.

So what is happening currently is around-the-clock work with maintenance, with the water systems, to make sure people that have been evacuated and the southern portion of the island has that water, because the volcano, it is a natural source of water, and they do use that. So of course, they can’t use it right now. So they have to try and find alternatives. So there’s quite a lot of bottled water being provided.

Air quality would be a bit poor. That’s why they have to make sure they protect their face and mouths, because essentially, volcanic ash is very tiny particles of rock and glass. So it’s very abrasive to your skin and to your eyes. And if you Inhale these, they can cause respiratory problems, particularly if you have asthma. That’s a problem. Yeah, even if you’re not in those pyroclastic flows, you still have to be careful because the volcanic ash is like a– it’s what we call a distal hazard, so something that impacts people farther away from the volcano.

IRA FLATOW: This is all fascinating. The last time La Soufriere erupted was back in 1979. What’s the legacy of this volcano for the communities around it? Are they used to it? Are they prepared? Are they not surprised? What does it mean?

JAZMIN SCARLETT: So with the legacy of the 1979 eruption– so essentially, after that eruption, for the past 40 years, there’s been continuous awareness and preparedness being put in place. So I was speaking to a colleague when this was happening, and I was quite worried. I had to be reminded that, actually, the one place, the one island, that would be prepared for this would be St. Vincent, because there’s been so much effort into preparing communities, and with the government as well, in terms of making sure their contingency plans are in place, making sure the emergency management plans are in place. They also have their own national emergency management organization that have been trained to deal with these kind of situations. So in terms of preparedness, they’re probably as prepared as they could be, I would say.

IRA FLATOW: Now I know that this volcano very well, because you did your PhD about La Soufriere. What is it like for you? If this were my– I would consider this to be my volcano if I were you. I’ve studied this. I’ve lived it. How does this all make you feel?

JAZMIN SCARLETT: If I’m honest, it still feels quite surreal, because when this was happening, even when the effusive activity in the lava zone started in December, I was thinking, like, I would at least be retiring age or– like, not in my lifetime that this would happen. So it’s quite surprising for me in terms of a person. But from a scientific standpoint, this is my time, my opportunity, to do more research on this.

IRA FLATOW: Do you feel like you should be there now, looking at it, documenting it, talking to the people?

JAZMIN SCARLETT: Absolutely. And I’ve been so frustrated that I can’t be there, because it’s really surreal, because my PhD essentially did a “What if this volcanic eruption happened today?” kind of scenario, minus COVID. And a lot of things I have actually predicted is actually happening right now, like, for example, I did talk about that people will stay behind, and that’s happened. I talked about disaster relief and the humanitarian assistance, and that’s happening now. I talked about how the evacuation would work, and that’s what’s happening as well.

So it is frustrating for me, because I could be there to help. And you know, this is not just me feeling this. It’s actually my colleagues, also, who are volcanologists in the UK who have studied La Soufriere– they’re also like, we should be there helping them, because more hands would actually make things go faster, our standards going normal or faster. So yes, I am very frustrated.

IRA FLATOW: Yeah, I can hear it in your voice. My heart and my good wishes go out to you and all the folks over there by the volcano.

JAZMIN SCARLETT: Thank you.

IRA FLATOW: Dr. Jazmin Scarlett, historical and social volcanologist, based in Newcastle-upon-Tyne in England.

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