The Strange Tonga Volcanic Eruption

Are you aware that the most powerful volcanic eruption in history recently occured in Tonga, on 15th Jan this year? Yes that's right, according to NASA scientists, the Hunga Tonga–Hunga Ha‘apai Volcano released the highest recorded plume since the eruption of Mount Pinatubo in 1991. The initial blast rose some 58 kilometres above the Earth, reaching the mesosphere, or the third layer of the atmosphere (NASA Earth Observatory, 2022). This was unusual as the volcanic vent is located underwater, between the Pacific and Indo-Australian Plates. Underwater volcanoes rarely tend to cause big explosions, yet the Tonga volcanic eruption was "more powerful than the atomic bomb the US dropped on Hiroshima" (BBC News, 2022). Reportedly, this was because the vent was too close to the surface for eruptions to be suppressed by ocean water (Witze, 2022). Furthermore, water can cause massive eruptions to happen through its capability to flash-heat (think of a water-heater being able to provide hot water instantly without storing hot water) to form steam, expanding quickly and fueling the volcano.   

Images from NOAA's Geostationary Operational Environmental Satellite 17 (GOES-17) depicting the different stages of the volcanic eruption. Source: NASA 

But what is really puzzling is that despite the astonishing height of the volcanic cloud, it was found to emit much less ash than expected. In particular, sulfur dioxide (SO2) emissions were found to be likely insignificant in causing climate change (Witze, 2022). It was found to only emit around 400,000 tonnes of SO2. In comparison, the Mount Pinatubo eruption which saw a plume 35 kilometres high released approximately 15 million tonnes, resulting in significant cooling of the Earth's surface for a period of 2 years (NASA Earth Observatory, 2001). Due to its unpredictable nature and difficulty in monitoring, scientists are still attempting to understand the causes of the eruption and its consequences for locals in the future, as it currently remains active. This event is particularly interesting as it serves as a reminder that the ocean is vastly unexplored, with forgotten parts, and these once-in-a-while occurrences can be devastating when unexpected. 

References: 

BBC News. (2022, January 24). Tonga volcano: Eruption more powerful than atomic bomb, Nasa says. https://www.bbc.com/news/world-asia-60106981#:%7E:text=A%20volcanic%20eruption%20in%20Tonga,’alofa%2C%20the%20agency%20said.

NASA Earth Observatory. (2001, June 15). Global Effects of Mount Pinatubo. NASA. https://earthobservatory.nasa.gov/images/1510/global-effects-of-mount-pinatubo#:%7E:text=Pinatubo%20injected%20about%2015%20million,primarily%20of%20sulfuric%20acid%20droplets.&text=In%20the%20case%20of%20Mount,period%20of%20almost%20two%20years.

NASA Earth Observatory. (2022, January 15). Tonga Volcano Plume Reached the Mesosphere. NASA. https://earthobservatory.nasa.gov/images/149474/tonga-volcano-plume-reached-the-mesosphere

Witze, A. (2022, February 9). Why the Tongan eruption will go down in the history of volcanology. Nature. https://www.nature.com/articles/d41586-022-00394-y?error=cookies_not_supported&code=5a2364c3-f13a-42bd-b3ff-b8ace230b275