MARY LOUISE KELLY, HOST:
You may have seen the images of lava shooting from the youngest and most active volcano on Hawaii's big island. The volcano in question is called Kilauea, and it has been spitting lava for more than a week. Scientists are now afraid it could be on the verge of a massive explosion, which prompted us to reach out to Wendy Stovall. She's a volcanologist with the U.S. Geological Survey and part of the team that is monitoring Kilauea. Wendy Stovall, welcome to the program.
WENDY STOVALL: Thank you. It's really nice to be talking to you today.
KELLY: We're glad to have you with us. So I want to start here. Kilauea has been simmering away, quietly erupting since 1983. So what has changed just in recent days?
STOVALL: Well, it actually all started about a month or a little bit over a month ago when we saw the volcano start to inflate kind of like a balloon. The ground was moving up. And that was a signal that things were about to change. Then a couple of Mondays ago, that eruption that had been continuing on quietly for 35 years kind of dropped out. The bottom of the crater floor fell away. And the magma supply that was feeding that volcano - magma is liquid rock, molten liquid rock under the ground. And it was feeding the volcano at the surface. But all of that magma kind of got squeezed down into a different part that - and that's kind of what's feeding the eruptions that are occurring on the surface.
KELLY: Was this a surprise that this happened?
STOVALL: It was - yeah, it was relatively a surprise. It wasn't a surprise when we saw the inflation of the volcano start to occur because that was definitely a signal that something was going to have to give. When the pressure builds up, when magma starts accumulating and making the volcano - making the ground rise of the volcano, then we know that the magma has to go somewhere.
KELLY: Why? I mean, isn't the pressure being released if it is continuously oozing and spitting lava, as we've all been watching in recent days?
STOVALL: The pressure is being released, but there's still - there's also pressure going into the system. So the other thing that's happening is there was another site of eruption, which is at the summit of the volcano, though now it's just this steaming vent. And the steaming vent is a sign that water is starting to interact with rocks. Rockfalls will continue to happen. And if enough of them happen, then they'll pile up and block the steam from getting out.
KELLY: Is that linked to - one of the more alarming headlines I read about this today was warning of a danger of boulders the size of refrigerators being shot into the air. Is that linked to what you're describing?
STOVALL: Yeah, exactly. That is linked to what I'm describing. So as those rockfalls fall into the vent, they'll plug up that steam. And then the steam will have to explosively evacuate the crater.
KELLY: So to sum up, it sounds like worst-case scenario is there might be a massive eruption and boulders the size of refrigerators being shot up. What's the best-case scenario? Could all this just quiet down and, you know, the steam escape and this return to its decades of simmering?
STOVALL: Yeah, that's probably the best-case scenario. Kilauea is an active system. It's in a perpetual state of eruption in some way or another. It does go quiet from time to time, but the quiet doesn't last. This is a volcano that is in its - in the stage of its life where it's building itself. It's amassing into something that might look akin to one of its neighboring volcanoes.
KELLY: Wendy Stovall, thank you.
STOVALL: Yeah, you're welcome. Thank you.
KELLY: That's Wendy Stovall with the U.S. Geological Survey and, as you heard there, part of the team monitoring Kilauea.
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