The eruption produced 2,600 flashes per minute at maximum intensity. Scientists used lightning to look into the ash cloud, and extracted new details for the eruption’s timeline.
- The Jan. 15 eruption lasted at least 11 hours, several hours longer than previously known
- The lightning plume produced the highest altitude flashes ever measured, 20 to 30 kilometers (12 to 19 miles) above sea level.
- Giant lightning “waves” rippled across a volcanic plume
- Lightning data reveal previously unknown phases of an eruption, and inform future volcanic hazard monitoring
The eruption of Hongga Volcano in Tonga on January 15, 2022 continues to break records. According to a new study, the volcanic eruption created a “supercharged” thunderstorm that produced the most powerful lightning ever recorded. Researchers found that there were approximately 200,000 lightning flashes in the plume throughout the eruption, with a peak of more than 2,600 flashes every minute.
When the submarine volcano erupted in the South Pacific Ocean, it generated a column of ash, water and volcanic gases at least 58 kilometers (36 miles) high. The towering plume gave scientists useful information about the size of the eruption, but it also obscured the vent from the satellite view, making it difficult to track changes in the eruption as it progressed.
Refers to frames with optically detected lightning. At least four distinct lightning episodes occur from 04:16 to 05:51, followed by one final episode from 8:38 to 48:48. The initial and most prominent loop (visible in the first four frames) is centered at the leading edge of the gravitational wave within the upper canopy cloud. Pink circles delineate the lightning ring in two frames, and show an (average) expansion rate of more than 60 ms -1. The westward move of the upper canopy begins revealing a low level cloud by 05:37. White dashed polygons mark the locations of lightning, showing its westward motion with the stratospheric canopy cloud. Local islands are outlined in black. Credit: Van Eaton et al. (2023), Geophysical Research Letters, doi: 10.1029/2022GL102341
High-resolution lightning data from four separate sources–never used together before–has now allowed scientists to peer into this plume, teasing out new phases in the eruption’s life cycle and gaining insights into the strange weather it generated.
“This volcanic eruption created a supercharged thunderstorm like we’ve never seen before,” said Alexa Van Eaton, a USGS volcanologist who led the study. “These findings demonstrate a new tool we have to monitor volcanoes at the speed of light and assist the USGS’ role in communicating ash hazard warnings to aircraft.” The study has been published inGeophysical Research Letters
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Van Eaton said the storm developed because a very active expulsion of magma occurred in the shallow ocean. Molten rock vaporized seawater, which rose to the spine and eventually formed electrical collisions between volcanic ash, supercooled water and hailstones. The perfect storm of lightning.
More than 200,000 lightning flashes, shown as blue dots, occurred throughout the course of the eruption at Hongga Volcano in Tonga on January 15, 2022. New analyzes of the eruption’s lightning intensity revealed that the volcanic storm was the most intense ever recorded and provided new insights into the evolution of eruption. Credit: Van Eaton et al. (2023), Geophysical Research Letters, doi: 10.1029/2022GL102341
Incorporating data from sensors that measure light and radio waves, the scientists tracked the lightning flashes and estimated their heights. The eruption produced just over 192,000 flashes (consisting of approximately 500,000 electrical impulses), with a peak of 2,615 flashes per minute. Some of this lightning reached unprecedented heights in the Earth’s atmosphere, ranging from 20 to 30 kilometers (12 to 19 miles) high.
“With this volcanic eruption, we discovered that plumes can create conditions for lightning that are far from the realm of atmospheric thunderstorms that we observed earlier,” Van Eaton said. “It turns out that volcanic eruptions can create more intense lightning than any other type of storm on Earth.”
The lightning provided insight not only into the duration of the eruption, but also its behavior over time.
“The eruption lasted much longer than the hour or two initially observed,” Van Eaton said. The Jan. 15 activity generated plumes for at least 11 hours. It was really only by looking at the cursory data that we were able to pull out.”
The researchers saw four distinct phases of volcanic activity, determined by plume heights and rates of lightning as it waxed and waned. Van Eaton said the insights gained from linking lightning intensity to volcanic activity could provide better monitoring and real-time prediction of aviation-related hazards during a large volcanic eruption, including ash cloud development and movement. Obtaining reliable information about volcanic plumes at the onset of an eruption is a major challenge, especially for more distant underwater volcanoes. Harnessing all available long-range observations, including lightning, improves early detection to keep planes and people out of harm’s way.
“It wasn’t just the intensity of the lightning that drew us in,” Van Eaton said. She and her colleagues were baffled by the volcano’s concentric lightning rings, which expand and contract over time. “The size of these lightning rings has blown our minds. We have never seen anything like this before, and there is nothing comparable in meteorological storms. Single lightning rings have been observed, but they are not doubled, and they are small in comparison.
Heavy high-altitude turbulence was again responsible. The plume pumped so much mass into the upper atmosphere that it sent ripples in the volcanic cloud, like dropping pebbles into a pond. The lightning appears to “surf” these waves and move outward in rings 250 kilometers wide.
As if all that wasn’t enough to make this eruption awesome, it’s a style of volcanism known as a phreatoplinian, which occurs when a large volume of magma blasts through water. Previously, this eruption style was known only from the geological record and had never been observed with modern instruments. The eruption of Heng changed all that.
“It was like taking out a dinosaur and seeing it walk around on four legs,” said Van Eaton. “Kind of takes your breath away.” Reference: “Lightning Loops and Gravitational Waves: Insight into the Giant Eruption Plume from Tonga’s Hongga Volcano on January 15, 2022” by Alexa R Van Eaton, Jeff Lapierre, and Sonya A. Christopher Bedka and Konstantin Khlopenkov, June 20, 2023, Available here.Geophysical Research Letters
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