New Array Captures Redoubt Volcano Lightning

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When Redoubt Volcano in Alaska started rumbling in January, a team of researchers from New Mexico Tech hurried to south central Alaska to deploy a series of radio sensors. When the volcano began erupting overnight on March 22 and 23, the Lightning Mapping Array started returning clear and dramatic information about the electricity created within volcanic plumes and the resulting lightning. This is the first time ever anyone has been able to record data from a volcanic eruption right from the start. “We’re getting all the data we hoped to get and a lot more,” principal investigator Dr. Ron Thomas said. “Absolutely, the quality and quantity of the data will allow us to better understand the electrical charge structure inside a volcanic plume.”

Lightning is a frequent occurance during volcanic eruptions. The Lightning Mapping array allows scientists, meteorologists and storm chasers to pierce the veil of clouds to “see” lightning as it occurs.

“With each lightning flash, we’ll be able to monitor how it moves through the clouds and where it goes,” Thomas said. “If we take all our theories about lightning created in thunderstorms, we can learn about both types of lightning.”

Photo of lightning from Redoubt Volcano during its 11:20 p.m. eruption on March 27, 2009. Photo by Brentwood Higman.

Redoubt erupted explosively about 20 times in the first seven days of activity. Most volcanic eruptions have several distinct stages. In the case of Redoubt, a stage of explosive activity is followed by a second stage that includes dome-building and slow venting of ash, rock and gasses. Within the individual explosive eruptions, different phases of electrical activity are observed.

“First, we see an eruptive or explosive phase,” physics professor Paul Krehbiel said. “Electrical activity is continuous and strong. We see a lot of small electrical discharges as hot gasses come out of the volcano.”
The second phase involves the ash cloud as it drifts away from the volcano with the wind. This phase is punctuated by discrete lightning – or lightning bolts.

“After the explosion is over, there is a subsequent phase of plume lightning,” Krehbiel said. “Full-fledged lightning occurs in the cloud of ash and water both above and downwind of the volcano.”

During a week’s time, Redoubt has had several major eruptions that have produced prolific lightning, Krehbiel said.

“The lightning activity was as strong as or stronger than we have seen in large Midwestern thunderstorms,” Krehbiel said. “The radio frequency noise was so strong and continuous that people living in the area would not have been able to watch broadcast VHF television stations.”

View north into the summit crater of Redoubt volcano where recent eruptions have removed a significant portion of the glacial ice. A remnant shelf of ice remains on the west (right) side of crater, and in this view, fumaroles are rising from near the ice/wall-rock contact. Image Creator: Payne, Allison

The Redoubt eruptions are not over yet. After quieting down and appearing to go into a dome-building phase, just before sunrise Saturday, April 4, the volcano blew its top in the biggest eruption so far.
Thousands of individual segments of a single lightning stroke can be mapped with the Lightning Mapping Array and later analyzed on high-end computers to reveal how lightning initiates and spreads throughout a thunderstorm … or within a volcanic plume.

“We receive radio bursts of noise generated from sparks of lightning, just like the static you hear on your car radio during a thunderstorm,” Thomas said. “We will use our sensing stations to locate the lightning and track its path.”

Source: New Mexico Tech press release

Nancy Atkinson

Nancy has been with Universe Today since 2004, and has published over 6,000 articles on space exploration, astronomy, science and technology. She is the author of two books: "Eight Years to the Moon: the History of the Apollo Missions," (2019) which shares the stories of 60 engineers and scientists who worked behind the scenes to make landing on the Moon possible; and "Incredible Stories from Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos" (2016) tells the stories of those who work on NASA's robotic missions to explore the Solar System and beyond. Follow Nancy on Twitter at https://twitter.com/Nancy_A and and Instagram at and https://www.instagram.com/nancyatkinson_ut/

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