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Tonga Update

19 January 2022
Geology

William sent in the link https://www.yahoo.com/news/heres-scientists-know-tonga-volcano-124800517… … while residents of the Tonga islands struggle to recover from a massive volcanic explosion and tsunami wave that swamped them not just with ash but with ocean water, scientists around the world are trying to understand the event in more detail. They don't think it will have a cooling effect on the global climate. The eruption was over too quickly and there was no massive emission of sulfur oxide. However, some localised weather changes may occur.

The shock wave produced by the explosive eruption, and the unusual tsunami waves it engendered, occurred as far away as the Atlantic and the Mediterranean, far from a direct or straight line trajectory of travel. Because communications in the islands went down there has been no news on the full nature of the damage. As tsunami waves temporarily drowned some of the smaller islands, and even affected the main island and capital of the country, little news has seeped out. New Zealand is sending in  relief supplies which will provide the outside world with a better picture of the situation and scale of the tragedy. Surprisingly, the eruption only lasted for 10 minutes, very different from other volcanoes. It was an apparent explosive event rather than an outpouring of magma. It produced a remarkable shock wave, that was vertical as well as horizontal. It went upwards beyond the stratosphere, 60 miles high. It then propagated around the earth at speeds of 600 mph. The force of the blast displaced large amounts of air outwards and upwards, high into the atmosphere. The shock wave fell back quite quickly and it is unclear if it had the ability to affect the jet streams. As it traveled high into the atmosphere it seems to also have had an effect on the oceans – causing them to oscillate.

The same story, with a different angle, is at www.nature.com/articles/d41586-022-00127-1 … where the headline reads, 'Tonga volcano eruption created puzzling ripples in earth's atmosphere', a reference to the shock wave, otherwise a pressure wave. Scientists have not witnessed this in previous volcanic eruptions, although the use of sophisticated equipment is confined to the modern world. The shock wave stretched from the volcano to the ionosphere – the electro-magnetic frontier. This is a really interesting admission as it is known sprites of lightning can do something similar during unusual atmospheric events, lightning having the ability to descend to the ground as well as ascend to the ionosphere.

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