Tonga volcano eruption created ripples in Earth’s atmosphere

'It was not until October that the first plausible explanation for “The Year without a Summer” was suggested. Friedrich Bessel, a German astronomer, reported seeing thick clouds of dust in the upper atmosphere. He theorized that these dust particles screened portions of Earth from the warming rays of the sun. It was discovered that in April 1815, Mount Tambora, an Indonesian volcano, had erupted with such force that it had sent an estimated 100 cubic miles of fine dust into the atmosphere. Witnesses to the eruption reported that the sky remained dark for two days. The dust then rose high into the stratosphere, where it encircled the world for several years to come.'

'Skeptics in 1816 doubted that a faraway volcano could steal their summer. However, most present-day researchers believe Bessel’s explanation to be generally correct, demonstrating the global nature of weather. The dust in the atmosphere eventually settled, and the spring of 1817 was back to normal.'

From https://shsatsunset.org/answers/q55-the-year-without-a-summe...

(I don't know the original source.)

Bessel could quite easily have used his math skills to try to explain a local earthquake as a consequence of this eruption.

My non-expert confidence doesn't count for much here, of course.

Modelling the specific events and characteristics of seawater infiltration to magma vents and chambers is well beyond my pay grade. I'm not representing to any extent that I've done this realistically. I'm simply showing what the maximimum potential vaporisation magnitude might be given a 6 MT energy input using a very naive heat of vaporisation conversion.

I'd noted the circularity in my note --- I'm estimating vapourisation effects and consequent blast yield using estimations of energy release which are based on the observed blast characteristics. Circular circularity is circularly circular.

The Axios article ... provides minimal insight on NASA's estimation methods. Though the comment on kinetic (blast) energies does suggest modeling based on the size, and probably rate of expansion, of the steam and ash plume. A forensic analysis of the 2020 Beiruit explosion discusses how total explosive force is estimated by blast diameter (see: https://forensic-architecture.org/investigation/beirut-port-...).

On thermal vs. blast effects: my estimate is based on the conversion of applied thermal energy into blast energy through vapourisation of water into steam. The 1,000-fold volumetric expansion provides that blast capability. It would then be much of the observed blast that the original 5--6 MT erruption energy is based on. My understanding is that "thermal effects" would refer to additional heat radiated from the erruption, exclusive of that heat which triggered the steam explosion itself.

The whole of the country heard it.

But basically it has to do with buoyancy. A cloud or other layering of the atmosphere has a stable place in the vertical column. If the atmosphere passes over a mountain range that displaces the column vertically, the column returns to its normal position. In returning, the atmosphere overcorrects repeatedly and "bounces" back into position much like a single jump onto a mattress.

[1] https://en.wikipedia.org/wiki/Gravity_wave

[2] https://twitter.com/ggweather/status/1427061411604099077

One 'splainer I've seen[1] described the volcanic erruption as the result of seawater infiltrating a magma chamber or vent, flash-vaporising, and basically blowing straight up to a height of about 30km (roughly 100,000 ft). Think of this not simply as a pressure wave blasting upwards, but as a bolus of air (and steam / water vapour) punching up through the atmosphere. It's analogous to a water wave spiking up out of fluid --- after it rises up, it will collapse back down, then rebound up, repeating this several times.

The spike also both propogates out and creates a gravity-wave front which propagates outward, again creating a vertical wave across the top of the atmosphere.

We're used to gravity waves in water largely because water isn't compressible. Sound travels through water, but shock waves tend to have limited reach since water itself doesn't compress --- a water shock is rapidly transformed into a water gravity wave, with a surge and collapse. (How much energy is transmitted through either wave mode I don't know, though someone versed in fluid dynamics could probably say.)

Air is compressible, so a major part of the effect of an explosion is shock. That said, you can get gravity waves in air as well, and the Tonga erruption is apparently a demonstration of this.

________________________________

Notes:

1. Possibly GeologyHub on YT: https://yewtu.be/channel/UCYeGh5VML5XPr5jYnzh3J6g Though I've been viewing / reading many sources.

Update: found it here: https://yewtu.be/watch?v=YcCkQaLkfxA

Compression (sound) waves are also material waves, so that term would generate its own ambiguity.

We could instead call the more recently detected gravitational waves "spacetime waves". Though I suspect someone might step in and make some observations about EMR in that context.