Rainfall Could Be A Factor In Triggering Some Volcanoes Extreme rainfall might set off volcanoes that are ready to blow. A pair of scientists think that's what happened at Hawaii's Kilauea volcano in 2018, though some volcanologists are doubtful.

Did Heavy Rain Cause Hawaii's Historic Volcanic Eruption?

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To some non-coronavirus news now. Scientists are making a bold new claim about what triggered a volcanic eruption in 2018. A volcano in Hawaii spent much of that year erupting in spectacular fashion. And as NPR's Nell Greenfieldboyce reports, two researchers now say it was set off by something unexpected.

NELL GREENFIELDBOYCE, BYLINE: In the spring of 2018 at Hawaii's Kilauea volcano, huge plumes of ash rose into the sky. New fissures opened up and spewed fountains of lava, forcing nearby residents to flee rivers of molten rock.

JAMIE FARQUHARSON: I think it's safe to say that most of the volcanological community was pretty fascinated by the event as it was unfolding.

GREENFIELDBOYCE: Jamie Farquharson is a volcanologist at the University of Miami. He and a colleague have just published a report in the journal Nature showing how this mighty volcano could have been affected by the weather; specifically, lots and lots of rain.

FARQUHARSON: The key conclusion is that the anomalous high amounts of rainfall in the lead-up to the eruption were actually critical in triggering the eruption itself.

GREENFIELDBOYCE: He says this is because all that rainwater would have penetrated the island's porous ground, going deep down more than a mile. It would build pressure within the rock. This could have opened up fractures and created new paths for hot magma. It's a view shared by his co-author, Falk Amelung.

FALK AMELUNG: It is very difficult to really prove it.

GREENFIELDBOYCE: Amelung says there have been past reports of rainfall possibly triggering other volcanoes when rain hit hot material much closer to the surface and explosively turned into steam. He also points to records going back to 1790 that suggest Kilauea is more likely to erupt in the most rainy parts of the year.

AMELUNG: And the physics is very clear. If you put water into the rock, then it's going to get weaker. So yeah, I hope people are going to believe it. That's going to be controversial.

GREENFIELDBOYCE: And experts at the Hawaiian Volcano Observatory are skeptical. They say they saw a buildup of pressure in the volcano's internal system of molten rock before the eruption and that this would be sufficient to explain why it happened when it did. Christina Neal is the scientist in charge there.

CHRISTINA NEAL: In this particular case, our data and our observations and interpretation lead us to a different conclusion, but that's just part of the normal scientific process where ideas are debated in the literature.

GREENFIELDBOYCE: She expects this debate will continue in the weeks and months ahead.

Nell Greenfieldboyce, NPR News.


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