While Tonga resident A. struggle to overcome devastating volcanic eruption Scientists are trying to better understand the global effects of the eruption, which crushed the Pacific island nation ashore and filled it with water.
They already know the answer to an important question: although it appears to be the largest eruption in the world in three decades, the eruption of the Hunga volcano on Saturday will not have a temporary cooling effect on global climate, as has been the case in some past massive eruptions. .
But after the event, there may be short-term effects on weather in some parts of the world and possibly minor disruptions to radio transmissions, including those used by the Global Positioning System.
A satellite photo provided by NOAA/Cira/Rammb shows the underwater volcano Hunga Tonga-Hunga Haapai eruption in an image from a weather satellite. (NOAA/SIRA/Ramb via The New York Times)
The shock wave generated by the explosion, as well as the unusual nature of the tsunami generated, will cause scientists to study the phenomenon for years. Tsunamis were found not only in the Pacific, but also in the Atlantic, Caribbean and Mediterranean regions
“It’s not that we weren’t aware of volcanic eruptions and tsunamis,” said Lori Dengler, an emeritus professor of geophysics at Humboldt State University in California. “But it’s really phenomenal to see this with the modern equipment we have.”
The eruption of an underwater volcano, formally known as Hunga Tonga-Hunga-Hapai, rained dangerous ash into the region, including the Tongan capital, Nuku’alofa, about 40 miles south. A 4-foot tsunami also hit the capital and higher wave heights were recorded elsewhere.
The government called the explosion an “unprecedented disaster”, although the full extent of the damage has been difficult to determine as the explosion destroyed telecommunications cables under water and ash forced the closure of Tonga’s airports.
Beyond Tonga, however, the enormity of the eruption was clearly evident. Clouds of dirt seen in satellite images, rock, volcanic gases and water vapor several hundred miles in diameter, and a narrow plume of gas and debris rose about 20 miles into the atmosphere.
Some volcanologists compare the devastating eruption of Krakatau in Indonesia in 1883 and the most recent massive eruption of Mount Pinatubo in the Philippines in 1991.
Pinatubo erupted over several days, sending about 20 million tons of sulfur dioxide gas into the stratosphere, or upper atmosphere.
That had the effect of cooling the atmosphere by about 1 degree Fahrenheit (about half a degree Celsius) for several years. (It’s also the mechanism of a controversial form of geoengineering: the use of planes or other means to continuously inject sulfur dioxide into the stratosphere to deliberately cool the planet.)
A general view from a New Zealand Defense Force surveillance flight shows heavy ash falling on Nomuka in Tonga, when the Pacific island nation was hit by a tsunami triggered by an underwater volcanic eruption. (Source: New Zealand Defense Force via Reuters)
The “Hunga eruption” was matching Pinatubo’s power at its peak, said volcanologist Shane Cronin of the University of Auckland in New Zealand, who has studied earlier eruptions at the volcano.
But the Hunga eruption lasted only 10 minutes, and in the days that followed, satellite sensors carried about 400,000 tons of sulfur dioxide into the stratosphere. “The amount of SO2 released is very small compared to Mount Pinatubo,” said Michael Manga, a professor of earth sciences at the University of California, Berkeley.
So unless Hunga’s eruption resumes and continues at an equally strong level, which is considered unlikely, it will not have a global cooling effect.
Cronin said the force of the explosion was related to its location, about 500 feet under water. When superhot molten rock, or magma, collides with seawater, the water immediately turns into steam, triggering the explosion manifold. Had it been too deep, the water pressure would have dampened the explosion.
The shallow depth, he said, created the perfect “almost Goldilocks” conditions for supercharging the explosion.
Corwin Wright, an atmospheric physicist at the University of Bath, said the explosion produced a shock wave in the atmosphere that was one of the most extraordinary events ever observed. England, Satellite readings showed that the wave reached far beyond the stratosphere, reaching heights of 60 miles, and spreading around the world at speeds of more than 600 mph.
“We’re seeing a really big wave, which is the biggest wave we’ve ever seen in the data we’ve been using for 20 years,” Wright said. “We haven’t really seen anything that covers the entire Earth in this way, and certainly not from a volcano.”
The wave resulted when the force of the explosion displaced vast amounts of air outward and upward, into the higher atmosphere. But then gravity pulled him down. It rose again, and this up-and-down oscillation continued, producing a wave of alternating high and low pressure that moved outward from the explosion source.
This satellite image taken by Himawari-8, a Japanese weather satellite operated by the Japan Meteorological Agency and released by the National Institute of Information and Communications Technology (NICT), shows an undersea volcanic eruption in the Pacific nation of Tonga on Saturday, Jan. 15, 2022. (NICT via AP)
Wright said that although the waves occur at high levels in the atmosphere, it could potentially have a short-term effect on weather patterns close to the surface, perhaps indirectly by influencing the jet stream.
“We don’t know completely,” he said. “We’re going to see what happens over the next few days. It can only interact through ripples and not interact.”
Wright said that because the wave was so high, it could potentially have little effect on radio broadcasts and signals from Global Positioning System satellites as well.
The atmospheric pressure wave may have played a role in the unusual tsunami as well.
Tsunamis are generated by the rapid displacement of water, usually by the movement of rock and soil. Large underwater faults can generate tsunamis when they run into earthquakes.
Volcanoes can also cause tsunamis. In this case, underwater eruptions, and the collapse of the crater of the volcano can lead to displacement. Or a side of a volcano may have become unstable and collapsed, with the same result.
But it would only be attributable to the local tsunami that submerged Tonga, the scientists said. More generally, said Gerard Fryer, an affiliated researcher at the University of Hawaii at Manoa who previously worked at the Pacific Tsunami Warning Center. “You would expect the energy to decay with distance,” Freire said.
But the event generated local tsunamis of roughly the same size in Japan, Chile and the west coast of the United States, and over several hours, and eventually smaller tsunamis in other basins around the world.
This is an indication that the pressure wave may have an impact on the ocean as it moves through the atmosphere, causing it to oscillate.
It would take weeks or months to analyze the data to determine what happened, but some researchers said this was a possible explanation.
“We know that the atmosphere and ocean are coupled,” Dengler said. “And we see a tsunami in the Atlantic Ocean. It didn’t go around the tip of South America to get there.”
“The evidence is pretty clear that the pressure wave played a role. The question is how big of a chunk.”
This article originally appeared in The New York Times.
,