Jonathan Amos*1 “Tonga eruption was 'record atmospheric explosion'” https://www.bbc.com/news/science-environment-61452860
今年１月に起きたトンガの海底火山Hunga-Tonga-Hunga-Ha’apaiの噴火*2は近代的な機器で測定されたものとしては、大気圏内における史上最大の爆発であったという。20世紀の如何なる火山噴火よりも、また第二次世界大戦後の如何なる核実験よりも強力な爆発。
さて、ここで注目されているのは「ラム波」という波*3。
The papers discuss at length the perturbations driven by so called Lamb waves, named after the early 20th Century mathematician Horace Lamb*4 .These are energetic waves in the air that propagate at the speed of sound, along a path guided by the surface of the planet. They are also non-dispersive, in other words they maintain their shape as they move and so are conspicuous over a long time.
The Lamb wave pulses produced by the Tonga eruption were seen to circle the Earth at least four times.
In the UK, which is some 16,500km from Tonga, these pulses began arriving on the evening of the 15th, about 14 hours after the climactic eruption on the other side of the planet.
They lifted the clouds over the UK.
*1:See also https://sumita-m.hatenadiary.com/entry/20180324/1521902369 https://sumita-m.hatenadiary.com/entry/20180330/1522380309 https://sumita-m.hatenadiary.com/entry/2020/10/08/094851 https://sumita-m.hatenadiary.com/entry/2021/09/11/085351
*2:See also https://sumita-m.hatenadiary.com/entry/2022/01/17/152837 https://sumita-m.hatenadiary.com/entry/2022/01/19/132305 https://sumita-m.hatenadiary.com/entry/2022/01/21/095845 https://sumita-m.hatenadiary.com/entry/2022/02/09/162221
*3:See eg. https://en.wikipedia.org/wiki/Lamb_waves https://ja.wikipedia.org/wiki/%E3%83%A9%E3%83%A0%E6%B3%A2
*4:See eg. Department of Mathematics, University of Manchester “Sir Horace Lamb” https://www.mub.eps.manchester.ac.uk/maths-student-blogs/2020/04/sir-horace-lamb/ https://en.wikipedia.org/wiki/Horace_Lamb
