The atmospheric plume from an underwater volcano eruption in the Pacific nation of Tonga is pictured from the International Space Station as it orbited 269 miles above the Pacific Ocean northwest of Auckland, New Zealand [image credit: NASA / Kayla Barron @ Wikipedia]
This NASA animation leaves little room for doubt about how powerful the Tonga event was. The very low-frequency sound waves it produced were first predicted by Laplace over 200 years ago, as the article below explains.
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The Hunga Tonga-Hunga Ha’apai eruption reached an explosive crescendo on Jan. 15, 2022, says Kevin Hamilton @ The Conversation (via Phys.org).
Its rapid release of energy powered an ocean tsunami that caused damage as far away as the U.S. West Coast, but it also generated pressure waves in the atmosphere that quickly spread around the world.
The atmospheric wave pattern close to the eruption was quite complicated, but thousands of miles away it appeared as an isolated wave front traveling horizontally at over 650 miles an hour as it spread outward.
NASA’s James Garvin, chief scientist at the Goddard Space Flight Center, told NPR the space agency estimated the blast was around 10 megatons of TNT equivalent, about 500 times as powerful as the bomb dropped on Hiroshima, Japan, during World Word II.
From satellites watching with infrared sensors above, the wave looked like a ripple produced by dropping a stone in a pond.
The pulse registered as perturbations in the atmospheric pressure lasting several minutes as it moved over North America, India, Europe and many other places around the globe.
Online, people followed the progress of the pulse in real time as observers posted their barometric observations to social media. The wave propagated around the whole world and back in about 35 hours.
I am a meteorologist who has studied the oscillations of the global atmosphere for almost four decades. The expansion of the wave front from the Tonga eruption was a particularly spectacular example of the phenomenon of global propagation of atmospheric waves, which has been seen after other historic explosive events, including nuclear tests.
This eruption was so powerful it caused the atmosphere to ring like a bell, though at a frequency too low to hear. It’s a phenomenon first theorized over 200 years ago.
Krakatoa, 1883
The first such pressure wave that attracted scientific attention was produced by the great eruption of Mount Krakatoa in Indonesia in 1883.
Continued here.
via Tallbloke’s Talkshop
January 25, 2022 at 06:51AM
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