Kilauea has been erupting since 1983 -- can scientists predict when it will stop?

JUDY WOODRUFF: Finally, science correspondent Miles O'Brien joins a researcher who ventures close to the glowing heart of an active Hawaiian volcano to learn what makes them tick.

It's the latest in our weekly Leading Edge series.

MIKE GARCIA, University of Hawaii: OK.

MILES O'BRIEN: If you want to learn what makes a volcano erupt, you need to go right to the otherworldly source, the crunchy, oozing, red-hot source. At least, that's what geologist Mike Garcia does.

MIKE GARCIA: Voila.

MILES O'BRIEN: Wow. That's amazing.

Amazing, indeed. Welcome to the most studied volcano in the world, Kilauea. Garcia and I came here to this surreal landscape on Hawaii's Big Island by helicopter. On our way, we got a glimpse of the red rock cauldron of magma through the sulfur-tainted steam.

Kilauea is one of the longest currently erupting volcanoes on the planet. The lava started flowing in January of 1983.

MIKE GARCIA: So, the mantle is producing an enormous amount of hot material that's coming out of Kilauea. This is probably one of the most active periods of the historical record of Kilauea.

MILES O'BRIEN: The eruption waxes and wanes, at times spewing fountains of lava, and, in the 1990s, threatening and destroying nearby homes.

But, of late, it's been more spectacle than menace, a slow-motion window into what lies beneath the surface.

Through it all, there is one constant here besides flowing lava: Garcia. He has been studying Kilauea for 30 years, hoping to improve eruption forecasting.

MIKE GARCIA: Well, with most volcanoes, you want to know when it's going to erupt. And so that's a primary concern. But, in this case, where we have an eruption that's been going on for over 30 years, the big question is, when is it going to stop?

MILES O'BRIEN: He comes here looking for data, in this case a piece of freshly cooked earth just out of the oven. He dunks it in water, freezing the moment and its chemical composition in time, a geological Instagram packed with data.

MIKE GARCIA: We know its birthday. We know when it was erupted. And you might ask, well, why do we — why do we care? Because the lava composition changes hourly, daily, or — and even monthly.

MILES O'BRIEN: And somewhere in there might be some sort of telltale sign of whether it's going to continue erupting or not, right?

MIKE GARCIA: Absolutely.

In science, one of the key things we do now are time series studies, where we collect samples repeatedly during the course of an eruption or in the ocean, because it's evolving all the time.

MILES O'BRIEN: Back in his lab at the University of Hawaii in Honolulu, graduate student Kendra Lynn does her part to understand Kilauea, shaving rocks into 30-micron slices, and then analyzing them using an electron microprobe.

She is interested in this green mineral called olivine. It is the most common mineral that forms at Kilauea.

What can we learn from it?

KENDRA LYNN, University of Hawaii: Because it's the first thing to crystallize in these magmas, it tells us a lot about the mantle source, where the magmas came from. And it can also tell us a lot about the magma's history.

MILES O'BRIEN: This is just one of many tests the team routinely conducts to analyze the elements and isotopes in the newborn rocks.

MIKE GARCIA: Each of the processes within the volcano leaves a fingerprint. So, over the years, we have been able to develop an understanding of what those fingerprints are and what they tell us about what's going on in the volcano.

MILES O'BRIEN: So, where are we right now? What is this?

MIKE GARCIA: We're looking at the rock collection we have from the Pu'u 'O'o eruption, as well as some of the other Hawaiian eruptions.

MILES O'BRIEN: And over the years he has amassed an impressive collection of rocks, not just from Kilauea, but from volcanoes all over the Hawaiian islands.

MIKE GARCIA: So, this is July 23 of 1997. And this one looks a little grayer.

MILES O'BRIEN: Yes, it's not quite as shiny, for whatever reason. Why would that be?

MIKE GARCIA: But you can see the imprint. Well, it was a little cooler at the time it was quenched.

MILES O'BRIEN: Ah, I see.

If only these rocks could talk. Fortunately, Garcia is pretty adept at reading them. One of the things he focuses on is the temperature of the lava.

MIKE GARCIA: So, what we have seen is a long-term decrease. Initially, the lava temperature was low. It increased. The eruption roared upward.

And now it's been slowly waning as — and we see the temperature of the lava is indicating a decrease. So, we think this eruption might end in the near future. But it's ended several times in the past. It was quiet in 1997 for a month, and then it restarted.

MILES O'BRIEN: Back at the lava flow, Garcia told me his work is not as dangerous as it seems, a calculated risk for a good scientific cause.

All right, so what is the strategy for walking? How do you know what to step on?

MIKE GARCIA: We need to avoid areas that look shelly, indicating that the lava has drained out from underneath. So we try to look for places where it looks solid, so we can avoid collapsing in on the lava flow.

MILES O'BRIEN: I'm just going to follow you. How's that?

MIKE GARCIA: Very good.

MILES O'BRIEN: But while we were here, some newly minted, still hot Hawaiian earth melted the soles right off of his shoes.

Wow, just like that. Is the other one already gone?

MIKE GARCIA: No, no. Oh, you're absolutely right.

MILES O'BRIEN: Holy moly. Wow.

All in a day's work for an intrepid geologist determined to go with and to the flow.

MIKE GARCIA: Success.

MILES O'BRIEN: Miles O'Brien, the "PBS NewsHour," at the Hawaii Volcanoes National Park.

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