According to a recent study in the Geophysical Research Letters journal, the plume released by the 2022 eruption of the Hunga Volcano resulted in the most lightning flashes ever observed on Earth, surpassing any previously recorded storm.
Sonja Behnke, of Los Alamos National Laboratory’s Electromagnetic Sciences and Cognitive Space Applications group, noted,
“The eruption of Hunga Volcano was the largest volcanic explosion since Krakatau in 1883.”
How the 2022 Tonga volcano eruption created a record-breaking lightning storm
Volcanic eruptions can create ash plumes that trigger lightning at higher altitudes than usual. When the undersea volcano in Tonga erupted, it produced a plume that went more than 25 miles higher than typical thunderstorms. Lightning was seen at stratospheric altitudes (12 to 18 miles), where the air pressure is too low to support thunderstorm-like lightning. However, Tonga’s fast-rising volcanic plume may have created locally higher pressures to support the environment necessary for lightning.
After reaching its maximum height, the plume expanded outward as an umbrella cloud, creating fast-moving circular ripples known as gravity waves, comparable to a rock dropped in a pond. Donut-shaped rings of lightning expanded with the umbrella cloud and were as large as 174 miles in diameter. Similar “lightning holes” have been seen in thunderstorms, but never on this big of a scale.
The study, led by the US Geological Survey Cascades Volcano Observatory, discovered that the eruption generated 2,615 flashes per minute at its peak intensity, which lasted nearly five minutes. This peak lightning rate is significantly greater than the second most intense lightning event ever detected—993 flashes per minute—in a thunderstorm over the southern United States in 1999.
For reference, see Lightning rings and gravity waves: Insights into the giant eruption plume from Tonga’s Hunga Volcano on 15 January 2022. Geophysical Research Letters.
About the 2022 Tonga volcanic eruption
Since 2014, the Hunga Tonga–Hunga Haʻapai volcano has been considered relatively inactive. However, on December 20th, 2021, it erupted and sent particulates into the stratosphere. This caused a large plume of ash that could be seen from Nukuʻalofa, the capital city of Tonga, more than 40 miles from the volcano. This initial eruption ended at 02:00 on December 21st, 2021.
Between December 22nd and December 23rd, 2021, plumes containing sulfur dioxide spread over the Niuatoputapu, Haʻapai, and Vavaʻu island groups. Tonga Navy crew recorded explosions, steam plumes, and steam bursts on December 23rd. This was also when the first ground-based images of the eruption were created.
Between December 24th and December 27th, 2021, steam and gas emissions reached altitudes of 10.3–12.2 kilometers (6.4–7.6 mi). Ash plumes reached heights of only 3 km (1.9 mi). Satellite imagery on December 25th, 2021 revealed that the island had increased in size by 300–600 meters (980–1,970 ft) on its eastern side. Several surges of Surtseyan activity occurred during December 29th and December 30th, 2021. These were witnessed by passengers on a small South Seas Charters boat. Eruption plumes during the second half of December 2021 disrupted air travel to Tonga multiple times.
On January 11th, 2022, the Tonga Geological Services declared the island dormant as activity on it decreased. However, a larger eruption commenced on January 14th, 2022, at 04:20 local time. This sent clouds of ash 20 km (12 mi) into the atmosphere. The government of Tonga issued a tsunami warning to residents. Tongan geologists near the volcano observed explosions and a 5-kilometer-wide (3.1 mi) ash column between 17:00 and 18:30 local time later in the afternoon. An even larger Plinian eruption started the following day (January 15th, 2022) at 17:14 local time. The eruption column from this eruption rose 58 km (36 mi) into the mesosphere. The VAAC again issued an advisory notice to airlines. Ash from the eruption made landfall on the main island of Tongatapu, blocking out the sun. Loud explosions were heard 65 km (40 mi) away in Nukuʻalofa, and small stones and ash rained down from the sky. Many residents in Tonga were stuck in traffic whilst attempting to flee to higher ground.
The volcanic explosion produced a loud sound that was heard in Samoa, which is approximately 840 km (520 mi) away. The sound then traveled to more distant countries. Fiji, which is over 700 km (430 mi) away, reported hearing the sounds of thunder and the “thump” of the eruption was also reported in Niue and Vanuatu. Tremors and shaking buildings were felt by residents in southwestern Niue, around Alofi and Avatele.
The volcanic explosion caused atmospheric shockwaves to propagate around the globe. Satellites captured shockwaves propagating across the Pacific Ocean and a very wide eruption column. Shockwaves were reported as having gone around the earth as many as four times in Japan and Utah, and at least twice at the Blue Hill Meteorological Observatory in Massachusetts.
Intense lightning activity was recorded during the eruption phase. The Vaisala Global Lightning Dataset GLD360 detected lightning in the form of radio waves. From 14 to 15 January 2022, tens of thousands of lightning flashes occurred. Between 05:00 and 06:00 UTC on 15 January 2022, 200,000 flashes were recorded.
Preliminary observations showed that the eruption column ejected a large amount of volcanic material into the stratosphere, leading to speculation that it would cause a temporary climate cooling effect. Later calculations showed it injected an estimated 400,000 tons of sulfur dioxide into the stratosphere and was unlikely to have any global cooling effect. Despite this, the eruption had a cooling effect in the Southern Hemisphere, causing slight cooling of winters and spectacular sunsets. People living in the Southern Hemisphere experienced purple sunsets for a few months after the eruption. A cooling effect of 0.1–0.5 °C (0.18–0.90 °F) was expected to last until spring (September–November) 2022. The eruption was described as a once-in-a-thousand-year event for the Hunga caldera.
NASA satellite Aura detected the eruption using its microwave limb sounder. It measures ozone, water vapor and other atmospheric gases, and can penetrate obstacles such as ash clouds. The underwater explosion also sent 146 million tons of water from the South Pacific Ocean into the stratosphere. The amount of water vapor ejected was 10 percent of the stratosphere’s typical stock. It was enough to temporarily warm the surface of Earth. It is estimated that an excess of water vapour should remain for 5–10 years.
Image Credits
In-Article Image Credits
A four-hour observation of the January 2022 eruption over the southern Pacific Ocean from the GOES-West satellite. via CIMSS by Tim Schmit; NOAA with usage type - Public Domainvia Zenodo by Van Eaton, Alexa, Behnke, Sonja, Lapierre, Jeff, Vagasky, Chris, Schultz, Christopher, Pavolonis, Michael, Bedka, Kristopher, & Khlopenkov, Konstantin. (2023) with usage type - Creative Commons License
Shockwave from the Hunga Tonga eruption captured by GOES-17 (GOES-West) and shown using the Mid-level Water Vapor via Wikimedia Commons by Tim Schmit; NOAA with usage type - Public Domain
Featured Image Credit
via Zenodo by Van Eaton, Alexa, Behnke, Sonja, Lapierre, Jeff, Vagasky, Chris, Schultz, Christopher, Pavolonis, Michael, Bedka, Kristopher, & Khlopenkov, Konstantin. (2023) with usage type - Creative Commons License
