The eruption of Tonga’s Hunga Volcano in January 2022 was not only the largest explosive eruption of the century but also a record-breaking event in terms of the lightning it generated. The eruption, which blasted debris into the stratosphere, created a supercharged thunderstorm, producing an estimated 192,000 flashes of lightning in just 11 hours.
The eruption’s lightning storm peaked at a rate of 2,615 flashes per minute, making it the most intense lightning storm on record. Moreover, it produced the highest lightning flashes ever seen, 20 to 30 kilometers (12 to 19 miles) above sea level.
The Hunga Tonga-Hunga Ha’apai eruption created a plume of ash, water, and gas at least 58 kilometers high. The eruption triggered a thunderstorm of unprecedented scale. “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,” says volcanologist Alexa Van Eaton from the United States Geological Survey (USGS).
The researchers used a combination of optical and radio readings to create a complete set of data. Instruments measuring electromagnetic radiation in both visible and radio frequencies, including satellites in orbit and radio antennas on land, were used to detect pulses of electrical current. This data allowed the team to simulate the lightning storm happening above Hunga in real-time, despite the vastness and thickness of the plume.
The eruption, which started underwater, created perfect conditions for a supercharged lightning storm as volcanic ash, supercooled water, and hailstones collided. The lightning tended to ‘surf’ on giant waves generated by the eruption in the southern Pacific Ocean, with high-altitude turbulence sending out ripples of material. These waves formed rings that were up to 250 kilometers wide.
The lightning data also revealed four distinct phases in the eruption, which hadn’t been previously spotted. This discovery will aid future eruption forecasting and modeling, helping to predict threats to life should such a blast occur again.
The Hunga Tonga-Hunga Ha’apai eruption and the resulting lightning storm have provided researchers with invaluable data, shedding light on the power and potential of volcanic eruptions. The event underscores the importance of ongoing research and monitoring in understanding and predicting volcanic activity.