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The Tonga Volcano and Its Aftermath

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The Hunga Tonga–Hunga Ha’apai volcano erupted on Jan. 15, 2022, off the coast of Tonga, creating one of the largest eruptions the world has seen in three decades.

The intense eruption of this underwater volcano, a vent or fissure beneath the ocean’s surface, had a lasting impact on surrounding areas. It created tsunamis in the Pacific, Atlantic, Caribbean and Mediterranean oceans. The aftermath of the explosion prompted New Zealand to issue $100,000 NZD and send naval and air forces to help Tonga. Australia and China followed in providing aid as well.

The Tonga volcano eruption has piqued the interest of scientists because of its unusual nature. Underwater volcanoes, also known as submarine volcanoes, differ from terrestrial volcanoes because they erupt into water and not directly into the atmosphere. 

It is uncommon for an underwater volcano to have large explosions because of the pressure the water above it creates, leaving the surface of the water undisturbed. However, the explosion of the Tonga volcano was extremely severe despite being an underwater volcano and created a large explosion nonetheless. 

The 300-mile-wide Tonga volcano eruption caused ash to climb more than 34 miles into the atmosphere, resulting in a cloud of debris, including rocks and ash, floods and tsunami waves of up to 15 feet in the surrounding area, reaching as far as Japan, Peru and the United States’ Pacific coast. Over Hawaii, clouds were formed, which was likely a result of the upward motions by shockwaves, a strong change in pressure traveling caused by the explosion, moving at a rate of 300 meters per second (mps), more than the average 200 mps that tsunami waves typically travel. 

As a result of its intensity, various other countries faced their own aftermaths. Puerto Rico was fronted with a meteotsunami, a tsunami caused by pressure waves from the tsunami that had spread across the Pacific ocean. Peru faced an oil spill from a ship because of the high waves near La Pampilla refinery. The powerful waves even prompted a tsunami advisory for parts of the west coast, with beaches in Orange County closing until the advisory was canceled. Japan’s coast was met with a tidal surge caused by the eruption and changes in atmospheric pressure. Chile was hit with a 1.74m wave in Chanaral.

In an interview with the NewU, Professor Julie Ferguson of the Earth System Science (ESS) department at UC Irvine, explained that the intensity of the volcano and the amount of ash is significant because “the presence of that ash acts to reflect some of [the] incoming sunlight, [in effect minisculely cooling] down global temperatures.”

Why? Ash in the atmosphere reflects incoming radiation, causing a cooling effect on the globe’s climate. Sulfur dioxide released from volcanic eruptions converts to sulfuric acid aerosols when combined with water in the atmosphere, blocking solar radiation and resulting in global cooling.  

However, despite world-wide impacts, the Tonga eruption will result in short-term weather effects and not cool the globe’s climate as a whole like past explosions of similar intensity have done. The amount of sulfur dioxide the Tonga volcano released into the stratosphere is not substantial enough to block solar radiation to the point of global cooling.

Ferguson elaborated on the effects of volcanic ash, explaining that although it didn’t result in global cooling, the people living near the eruption faced dangerous amounts of ash. She explained that unlike the fluffy ash we’re familiar with in a fireplace, “this ash is bits of rock, and if you build up piles of basically powdered rock, it’s heavy, and that causes problems because it can cause roofs to collapse.”

Buildings were destroyed and communication went out in Tonga, with internet traffic losing connection for approximately five days after the eruption. Ferguson also explained that the tiny rocks in the ash can be breathed in and damage the lungs, posing a health concern for the people of Tonga.

In addition to the health threat that ash poses to the residents of Tonga, the ongoing COVID-19 pandemic has become a health threat to them as well. Prior to the Tonga eruption, Tonga had been nearly COVID-19 free as its borders were locked since the start of the COVID-19 pandemic in an effort to prevent entry of the virus.

Aid deliveries were an immediate concern for the residents as it opened the possibility of someone inviting COVID-19 to their country. Tonga reported their first cases of COVID-19 by two workers who distributed aid shipments after the volcano erupted and the Prime Minister Siaosi Sovaleni announced a lockdown in response to these cases. Now, months since the eruption occurred, there have been 11,127 confirmed cases of COVID-19. This made it more difficult for tsunami and eruption clean up because of the increased COVID-19 precautions, making it difficult to respond effectively to clean up efforts. Cases of COVID-19 piqued at the end of March, and are now declining.

Giselle Garcia is a STEM intern for the winter 2022 quarter. She can be reached at gisellg8@uci.edu