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World's Largest Volcano Discovered on Pacific Seafloor


This is SCIENCE FRIDAY. I'm Ira Flatow. Scientists have discovered the world's largest volcano. But if you'd like to climb it, you first have to dive it because the Tamu Massif rests at the bottom of the Pacific Ocean. The volcano is so big - it's 60 times bigger than Hawaii's Mona Loa - that researchers have had to search the solar system to find a comparison and they found one on Mars, the Olympus Mons, which is the size of Arizona. In case you're worried, Tamu Massif last erupted 145 million years ago.

Here to talk about this massive volcano is Kayla Iacovino. She is a graduate student and researcher in the department of geology at the University of Cambridge, a former SCIENCE FRIDAY blogger. She joins us from BBC studios in Cambridge. Hey there. Welcome back.

KAYLA IACOVINO: Hi, Ira. It's good to be here.

FLATOW: Now, let's talk about this volcano. Where is it exactly?

IACOVINO: Well, it's basically, as you say, it's in the middle of the Pacific Ocean several kilometers underwater.

FLATOW: And how high up does it rise above the surface?

IACOVINO: It doesn't, actually. It's about two kilometers below the surface of the ocean water.

FLATOW: Oh, so it's hidden then.

IACOVINO: It's completely hidden and so that's one of the reasons we had never discovered it before and, well, we knew it was there, but what we didn't know was that it was actually one massive volcano. So we knew something was there, but we didn't know the nature of it. And this recent study that's been published was a big research effort that sent boats over the top of the volcano and used seismic sounding techniques to try to understand what the volcano looks like on the inside.

FLATOW: So how do we know how it got to be that big? Or do we not know?

IACOVINO: Well, that's the great thing about science is that when you answer one question, you often raise many more and that's one of the questions raised here. So what the research has shown is that this is, in fact, one large volcano where all of this magma and lava has been extruded from one source. But we don't quite understand the mechanics behind that.

So as you mentioned, Olympus Mons on Mars is the largest volcano in the solar system and before the discovery of Tamu Massif as one volcano, we didn't think that such a large volcano could even exist on the Earth. Many of the theories explaining how Olympus Mons came to be relies on the fact that it's on Mars.

So, for example, the lower surface gravity on Mars may enable lava to come out of the Earth at a faster rate and allow it to accumulate this large size. But now that we see one here on Earth, we have to come up with another way to explain why it's occurring here.

FLATOW: Are there any theories about it?

IACOVINO: Well, the underlying mechanism really, there must be some huge amount of hot magma beneath the surface before the volcano was formed which then came up through the oceanic plates that are moving apart at that location and all of this magma was released over a very long period of time likely, possibly in several events. And because the lava was coming out of the surface so quickly and it was so low in viscosity - that means it has a low stickiness factor. It was very runny. It could spread out very, very wide. Instead of piling up like a cone, we have a shield-shaped structure.

FLATOW: So how come it was found now. It's been around for quite a while.

IACOVINO: Yeah. Well, that's true. And as I said, we knew something was there, but we didn't know really what it was. And I'm a big proponent of space exploration, but what many people don't realize is that there are still many frontiers to be explored here on Earth and I think this pinpoints the fact that the Earth's oceans are not very well known or well studied.

One reason is just because, as you said, it's hard to get to. If you want to climb this volcano, you have to dive several kilometers below the surface. And so we have to use new technologies and new techniques to study these things.

FLATOW: Yeah, how do you actually define the shape? What kind of technology do you use?

IACOVINO: Well, in this study, they used some seismic imaging techniques where they essentially drove a boat over the top of it and shot air guns at the surface of the volcano. And those air guns provided impact onto the surface of the volcano which the waves traveled through the volcano and back up to the ship where they could read how those waves had responded to the materials in the Earth. And it's kind of like sonar or radar, they can see the layers of lava that have stacked up one upon the other to form the volcano's shape.

FLATOW: Kayla, if they have found this one, might they be saying, hey, there are other ones there we should go looking for.

IACOVINO: Oh, definitely. I mean, the fact that this exists raises a lot of questions about how it came to be and may there be others elsewhere in the world, and I think that's a definite possibility.

FLATOW: Mm-hmm. And are you interested? I know you are volcanologist. Are you interested in this sort of thing underwater? Because last time we talked to you, you were in Antarctica and looking down into a volcano.

IACOVINO: That's right. Well, I do find myself often in very strange places studying volcanoes and I would love to travel to the bottom of the seafloor to study another one.

FLATOW: Yeah. Well, good luck to you. We hope that wish comes true.

IACOVINO: Thanks so much.

FLATOW: Thank you very much for joining us.

IACOVINO: Good talking to you.

FLATOW: You, too. Kayla Iacovino, she is a graduate student and researcher in the department of geology at the University of Cambridge. Transcript provided by NPR, Copyright NPR.