How Big Was the Tonga Volcanic Eruption?

Caitlin Dempsey


The January 15, 2022 eruption of an undersea volcano near Tonga sent literal shockwaves around the world. The eruption of Hunga-Tonga-Hunga-Ha’apai sent ash, tephra (fragments of rock), volcanic gas, and steam 31 kilometers (19 miles) up into the atmosphere.

The eruption and the resulting tsunami has caused significant damage to the neighboring island of Tonga. Only 5% of tsunamis are caused by volcanic eruptions. Most tsunamis result from earthquakes.

Previous to the January 15 eruption, two earlier eruptions of moderate size occurred on December 20, 2021 and January 13, 2022.

How Big Was the Volcano’s Umbrella Cloud?

Earth observation satellites were able to captured the volcanic eruption located in the Tonga-Kermadec volcanic arc within the Pacific Ring of Fire.

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An umbrella cloud is the cloud formed by super-heated ash and gases expanding radially from the source of the volcano. At it’s widest extent, the umbrella cloud from the Tonga eruption was 500 kilometers (300 miles) in diameter.

Animated satellite imagery showing the umbrella cloud from an undersea volcanic eruption.
The eruption of Hunga Tonga-Hunga Ha‘apai was captured by NOAA’s Geostationary Operational Environmental Satellite 17 (GOES-17) on January 15, 2022.

How High was the Tonga Ash Plume?

NASA’s Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission was able to collect data showing that ash and volcanic gases reached an altitude of  31 kilometers (19 miles).

The force of the Hunga Tonga-Hunga Ha‘apai eruption was strong enough for volcanic material to reach the stratosphere which begins around above 15 kilometers (9 miles) in the region. If enough volcanic ash reaches the stratosphere it can creating a cooling effect on global temperatures.

Light and dark yellow shaded graphic showing how high the ash plume from a volcanic eruption reached into the atmosphere.
Volcanic plume from the Hunga Tonga-Hunga Ha‘apai eruption. Graph: NASA, public domain.

So far, scientists don’t believe the volcanic eruption of Hunga Tonga-Hunga Ha‘apai will have an impact on global temperatures. Current measurements indicate that 0.4 teragrams of sulfur dioxide reached the stratosphere from the volcanic eruption. 5 teragrams is the threshold needed to observe climatic impacts.

Shockwaves from the Tonga Eruption

The force of the volcanic eruption created shockwaves that were felt in Fiji (about 310 miles / 500 kilometers northwest), New Zealand (994 – 1,243 miles / 1,600-2,000 kilometers away), and nine hours later in Alaska (5,822 miles / 9,370 kilometers northeast).

Pressure waves from the Hunga-Tonga-Hunga-Ha’apai volcanic eruption traveled around the world three times before dissipating.

What Happened to Hunga-Tonga-Hunga-Ha’apai Island?

The conjoined island of Hunga-Tonga-Hunga-Ha’apai was created in December of 2014 during another undersea eruption of the volcano that connected two existing islands. Tephra from the 2014 eruption built up around a new volcanic cone that connected the islands of Hunga-Tung and Hunga-Ha’apai to form the new island.

Graphic showing Hunga-Tonga-Hunga-Ha'apai island.
How Hunga-Tonga-Hunga-Ha’apai island looked before the January 2022 eruption. Image: NASA, public domain.

Satellite imagery and remotely sensed data acquired since the January 15, 2022 eruption indicate that little of Hunga-Tonga-Hunga-Ha’apai island has survived above the water line. The volcanic eruption destroyed the connecting landmass and a significant portion of the two original islands.

A drawing showing that the interconnecting land between two oceanic islands has been destroyed.
Hunga-Tonga and Hunga-Ha’apai islands are once again separate after the January 2022 eruption. Image: NASA, public domain.


Cronin, S. (2022, January 15). Why the volcanic eruption in Tonga was so violent, and what to expect next. The Conversation.

Global Volcanism Program, 2022. Report on Hunga Tonga-Hunga Ha’apai (Tonga). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 12 January-18 January 2022. Smithsonian Institution and US Geological Survey.

Understanding a unique tsunami event caused by the Tonga volcano eruption. (2022, January 21). NOAA Pacific Marine Environmental Laboratory (PMEL).

Voiland, A., & Mike Carlowicz, M. (2022, January 18). Hunga Tonga-hunga Ha‘apai erupts. NASA Earth Observatory.

Voiland, A. (2022, January 21). Dramatic changes at Hunga Tonga-hunga Ha‘apai. NASA Earth Observatory.


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About the author
Caitlin Dempsey
Caitlin Dempsey is the editor of Geography Realm and holds a master's degree in Geography from UCLA as well as a Master of Library and Information Science (MLIS) from SJSU.