Kīlauea volcano eruption

Lava from Kilauea volcano by Hawaii volcanoes national park. (Credit: Maridav/Shutterstock)

EUGENE, Ore. — You’re probably familiar with the classic volcanic eruption caused by rising magma and clouds of ash and gas flowing out of tall mountains. However, researchers have discovered an entirely new type of eruption — and it took place very recently in Hawaii! In fact, scientists from the University of Oregon say 12 back-to-back explosions during the Kīlauea volcano eruption in 2018 are like nothing geologists have seen before.

The findings, in a nutshell

In the journal Nature Geoscience, study authors say these unique eruptions were the result of something similar to a stomp-rocket toy. As magma slowly drained from an underground reservoir, the ground above it suddenly collapsed inward. This rapidly increased the pressure in the reservoir, squeezing out a trapped pocket of volcanic gas and rubble in a powerful blast, like stomping on an airbag attached to the toy rocket. The scientists coined the term “stomp-rocket eruption” to describe this newly observed phenomenon.

While the stomp-rocket process has never been examined so closely before, it may actually happen fairly often, especially with smaller volcanic eruptions. The Oregon team says that understanding the nuances of eruptions, both big and small, improves our models of how volcanoes “plumb” magma in complex ways and can lead to better disaster preparedness.

This unique string of explosions at the summit of Kīlauea was part of an eruption that included lava flows spewing from a lower part of the volcano. Those lava flows destroyed thousands of homes and displaced residents on the Island of Hawai’i for months.

Kilauea Volcano Begins To Erupt
12 back-to-back explosions during the Kīlauea volcano eruption in 2018 are like nothing geologists have seen before. (Credit: Joe Belanger/Shutterstock)

How did scientists figure this out?

To solve the mystery, researchers turned to the wealth of data collected by the dense network of monitoring instruments keeping a round-the-clock watch on Kīlauea. From ground sensors measuring temblors to tools analyzing the volcano’s gaseous emissions, the team had an unprecedented glimpse into the underground dynamics preceding each explosion.

By crunching all those observations through detailed atmospheric and subsurface computer models, the scientists were able to reconstruct a chain of events unlike any eruption process documented before. It went something like this: As magma slowly drained from a reservoir deep beneath Kīlauea’s summit, the ground above it abruptly collapsed inward like a trapdoor. This sudden subsidence sharply compressed the partially emptied reservoir, explosively squeezing out a pocket of volcanic gas and rubble sitting at the top.

The researchers realized this mechanism was strikingly similar to the basic principle behind a classic child’s stomp-rocket toy, where jumping on an air bladder connected to a pipe or tube launches the toy skyward. Except in Kīlauea’s case, the “stomp” was a kilometer-thick slab of rock dropping down, and the “rocket” was a billowing plume of high-temperature ash and gas venting from the summit vent. All of this led to the new “stomp-rocket eruption” theory.

What do the researchers say?

“A cool thing about these eruptions is that there were a bunch of them in sequence that were remarkably similar; that’s relatively unusual,” says Leif Karlstrom, a volcanologist from the University of Oregon, in a media release. “Typically, volcanic eruptions don’t happen with as much regularity.”

“These eruptions are quite interesting in that they don’t really seem to involve either of those,” adds study author Josh Crozier, referring to the lack of both rising magma and vaporized groundwater. “The eruptive material contained very little that looked like fresh magma that was blasted out, but there’s no evidence for significant groundwater being involved, either.”

“It gives us a much more nuanced picture of what volcanic plumbing systems look like,” Karlstrom concludes.

About Chris Melore

Chris Melore has been a writer, researcher, editor, and producer in the New York-area since 2006. He won a local Emmy award for his work in sports television in 2011.

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