Tonga's Hunga eruption produced unprecedentedly intense lightning

New Delhi: With nearly 2,00,000 lightning flashes in its plume throughout the eruption, peaking at more than 2,600 flashes per minute, Tonga's Hunga volcanic eruption created a "supercharged" thunderstorm that produced the most intense lightning ever recorded, researchers have found.

Some of this lightning reached unprecedented altitudes in the Earth's atmosphere, between 20 to 30 kilometers high, the researchers said after having tracked these lightning flashes and combining data from sensors measuring light and radio waves.

The high energy with which magma was expelled through the shallow ocean caused the storm to develop, according to lead researcher Alexa Van Eaton, a volcanologist at the US Geological Survey (USGS).

Magma, or molten rock, vapourised the seawater, which rose up into the plume, forming electrifying collisions between volcanic ash, supercooled water and hailstones and thus, creating the perfect storm for lightning, she said.

"This eruption triggered a supercharged thunderstorm, the likes of which we've never seen.

"With this eruption, we discovered that volcanic plumes can create the conditions for lightning far beyond the realm of meteorological thunderstorms we've previously observed.

"It turns out, volcanic eruptions can create more extreme lightning than any other kind of storm on Earth," said Van Eaton.

While the towering plume of ash, water and magmatic gas (58 kilometres high) generated by the submarine volcano located in the southern Pacific Ocean gave scientists useful information about the scale of the eruption, it obscured the vent from satellite view, making it difficult to track changes in the eruption as it progressed.

Using high-resolution lightning data from four separate sources, never previously used all together, the researchers could peer into that plume, teasing out new phases of the eruption's life cycle and gaining insights into the weird weather it created.

"These findings demonstrate a new tool we have to monitor volcanoes at the speed of light and help the USGS's role to inform ash hazard advisories to aircraft," said Van Eaton, whose study is published in the journal Geophysical Research Letters.

She also said that the eruption on January 15, 2022, created volcanic plumes for at least 11 hours, much longer than the hour or two initially observed, which they found from looking at lightning data.

"It wasn't just the lightning intensity that drew us in," she said.

She and her colleagues were also puzzled by the concentric rings of lightning, centred on the volcano, that expanded and contracted over time.

"The scale of these lightning rings blew our minds. We've never seen anything like that before, there's nothing comparable in meteorological storms. Single lightning rings have been observed, but not multiples, and they're tiny by comparison," said Van Eaton.

Intense, high-altitude turbulence was again found to be responsible.

The plume injected so much mass into the upper atmosphere that it sent out ripples in the volcanic cloud, like dropping pebbles in a pond. The lightning appeared to 'surf' these waves and move outward as 250-kilometer-wide rings.

Further, the Hunga volcanic eruption represented the phreatoplinian style of volcanism, which occurs when a large volume of magma erupts through water and known only from previously recorded geological data.

"It was like unearthing a dinosaur and seeing it walk around on four legs," Van Eaton said. "Sort of takes your breath away."