As more details emerge about the January 15, 2022 eruption of Hunga Tonga-Hunga Ha’apai in the Pacific Ocean, it is becoming clearer what catastrophe the world may have been avoiding. The 11-hour eruption devastated parts of the Tonga archipelago, covering some islands with ash, destroying crops and killing at least three people. But the eruption under water probably prevented even greater damage. A study by Corwin Wright from the University of Bath and his team in »Nature« shows the force with which the volcano blew up.
The eruption not only drove ash clouds into the stratosphere and triggered mysterious waves in the atmosphere, but also chased pressure waves around the earth that reached a previously unknown speed. According to the evaluations by Wright and Co, they shot around the world at speeds of up to 1158 kilometers per hour: values that have not yet been measured in this way.
“The speed is very close to the theoretical maximum,” says Wright. In their analysis, the working group benefited from a large number of data from measuring stations distributed around the world, which recorded the eruption as well as numerous satellites. The waves that were triggered in the atmosphere were therefore in the range measured for the 1883 Krakatoa eruption. In any case, the eruption of Hunga Tonga is considered the strongest since 1991, when Pinatubo in the Philippines exploded.
The waves circled the earth at least four times in one direction and three times in the other direction. They also triggered so-called meteotsunamis: waves triggered by air pressure that occurred in the Pacific, Atlantic and Mediterranean, among other places. However, compared to a real tsunami, the wave heights were significantly lower. At the Kármán line, which marks the boundary between our atmosphere and space at an altitude of 100 kilometers, the shock waves created strong winds that reached speeds of up to 730 kilometers per hour.