Tonga Volcano Sparked the Most Intense Lightning Storm Ever Recorded

On January 15, 2022, the underwater Hunga Tonga-Hunga Ha’apai volcano blew its top in a massive eruption, propelling a giant plume of ash and gas beyond the stratosphere. It was the largest recorded eruption since 1991, when Mount Pinatubo erupted in the Philippines.

Now, researchers say the 2022 eruption prompted the most intense lightning rates ever recorded, per a new study published last week in the journal Geophysical Research Letters. At its peak, the raging lighting storm produced 2,600 flashes per minute.

The scientists also detected lightning as high as an estimated 12 to 19 miles above sea level. Previous research elsewhere has only recorded lighting up to roughly 11 miles above sea level, according to the study.

“We’ve never seen anything like this sheer rate of lightning before—and at such high altitudes,” study co-author Alexa Van Eaton, a volcanologist at the U.S. Geological Survey, tells Space.com’s Keith Cooper.

“This is a fascinating study and shows how the Tongan eruption influenced the Earth system in ways that you might not immediately associate with a volcanic explosion,” Sam Purkis, a geologist at the University of Miami who did not contribute to the research, tells the Washington Post’s Kasha Patel.

Located near the islands of Hunga Tonga and Hunga Ha’apai in the South Pacific Ocean, the volcano started spewing ash on December 19, 2021. But its activity peaked with the cataclysmic eruption on January 15, resulting in tsunamis that caused the deaths of four people in Tonga and two people in Peru, the Guardian’s Nicola Davis wrote in April. The tsunamis also displaced more than 1,500 people on Tongan islands, and the eruption impacted over 80 percent of Tonga’s population.

The volcanic plume shot out of the ocean and reached a height of at least 36 miles above sea level. At its most intense moments, the volcano spewed out material at a rate of about 11 billion pounds per second—that’s the weight of more than 15 Empire State Buildings every second.

“It was clear right away that this was going to be a showstopping scientific event,” Van Eaton tells the Washington Post. “It’s several orders of magnitude larger than anything we’re used to looking at … This eruption clearly was going to teach us something new.”

Since last year’s eruption, scientists have been studying the event and adding to an ever-growing list of ways it made history. The volcano increased the amount of water vapor in the stratosphere by 5 percent, one study found. And that massive amount of water vapor could trap enough heat to temporarily warm Earth’s surface, according to another study.

For the new paper, the researchers examined records of the eruption from satellites and ground-based radio antennas. When viewing satellite imagery of the blast, they watched the volcanic plume rise and spread outward. Surprisingly, the lightning flashes also spread outward in four concentric rings, which matched the four phases of the eruption, writes Space.com.

Researchers had previously identified lightning in this circular pattern, but this was the first time they spotted multiple lightning rings.

Lightning, which is caused by an imbalance of electrical charges, occurs during volcanic eruptions when bits of ash brush against each other, creating charged particles, and similarly, when ice particles become charged.

“It may be that larger particles were going one direction and smaller particles were going in another, and that helped create the charge separation that leads to electrical discharges,” Van Eaton tells the Washington Post.

Researchers theorize that the lightning storm was so strong because of the eruption’s intensity, the rapid expansion of the ash plume and the large amount of vaporized seawater in the plume.

The volcanic plume may also be to blame for the high-altitude flashes: It could have raised the air pressure, leading the lightning to occur so high above sea level, Van Eaton tells Science News’ Skyler Ware. At the typical low air pressures at higher altitudes, it’s more difficult to form the channels of plasma that are necessary for lightning, according to the paper.

On top of all the existing evidence for how powerful and unusual this eruption was, the study demonstrates another way that the volcano led to unexpected events on and around the planet.

“Hunga has completely changed the way we think of how natural events can change the atmosphere and the environment where we thought lightning could exist,” Jeff Lapierre, a co-author of the study and lightning scientist at the company Advanced Environmental Monitoring, tells Science News.

Will Sullivan | | READ MORE

Will Sullivan is a science writer based in Washington, D.C. His work has appeared in Inside Science and NOVA Next.