I'm not sure they do actually - for me it's rather the opposite.

Humans move vastly more material about on this planet than the forces of geology do and the long term feed of gasses we put into the atmosphere will have much more impact than this eruption on the atmosphere. 

The way I look at it, it's a very big volcanic eruption but a blip compared to the long term effect we are having. That is what puts it into perspective for me.

 A very impressive picture

...which doesn't seem to want to load anymore

And from here as well:

https://www.wunderground.com/dashboard/pws/ILEYSDOW1/graph/2022-01-15/2022-01-15/daily

It's also interesting how the pressure had been remarkably stable up until the shockwave hit, after the main shockwave it then became more erratic on the graph. Aftershocks? A distortion caused by the wave making the high wobble, so to speak? Who knows, but it's fascinating to see!

The link is working again this morning with pictures (though a further link to an animation is rather slow)

I'd love to know what the TNT equivalents are of this.

There's only about 2 or 3 volcanoes that have had explosions so violent that pressure waves have travelled round the world.

Tambora and Krakatoa come to mind.

Krakatoa was 220 megatons equivalent and the shock wave went round the planet 4 times.

Tsar Bomba the largest nuclear weapon ever detonated. That was detonated in 1961 and it was 51 megatons equivalent and that travelled round the world twice.

It may be this eruption was violent but short lived, so it's total 'VEness' () smaller. It does look a little like the island has been blown up. But then Krakatoa was a similar situation?

This is exceptionally cool: 

Using a difference overlay, I can accentuate that shockwave as it traverses the entire globe. The antipode of Tonga is over Northern Africa. #tonga #HungaTongaHungaHaapai @NWS @USGSVolcanoes pic.twitter.com/BNS0DsfLrm

— science.out.there (@ScienceOutThere) January 15, 2022

It might reflect a relatively small amount of material - one theory for the eruption is an earthquake or initial explosion caused part of the island to slide in to the sea, which allowed sea water to mix with the revealed magma and that went 'bang'. In that scenario there'd be a lot of steam, some ash but maybe not much more than that? I guess it could also have been a similar thing with part of the volcano that's underwater. 

There's a really cool radar image of before and after the eruption on the BBC:-

Pacific volcano: Ash-covered Tonga is like a moonscape say residents - BBC News

I know a large part of the island was relatively new and made of ash etc. from earlier eruptions so not exactly durable but even so it looks to have essentially destroyed it.

That said a VEI2 does still seem a little low given how large the ash cloud was and how high in to the atmosphere it went

The volcano is underwater and it's huge! Just parts of it stick out or at least they did. That huge ash cloud isn't a result of simple water & magma reacting but rather a deeper reserve of gas rich maga erupting. This eruption will have created a new caldera for sure. 

I think a strong VEI4 at the very least. 

This website has a detailed images of the volcano 

https://theconversation.com/why-the-volcanic-eruption-in-tonga-was-so-violent-and-what-to-expect-next-175035

I

But that sheer volume that was ejected into the atmosphere & spread hundreds of miles across in only a couple of hours, so perhaps more than what we might have thought possible has been ejected. Also it continued to erupt over night.

Ya, I get that. There's some interesting stats and images in that article too, as you say shows the scale of the volcano nicely. (Kind of reminds me of the Krakatoa crater with just small islands left above the sea).  

It'll be interesting to see what they decide the exact cause was over the coming days. The seawater being in the mix would have increased the explosivity of the eruption I think, given the type of eruptions that volcano produces (i.e it generally erupts explosively rather than a relatively slow fissure style eruption, so any interaction with water would have been lots of magma all at once and lots of water flashing to steam has to go somewhere). 

The partial collapse leading to violent eruption theory was on one of GeologyHubs videos on Youtube (No idea what qualifications the person has who makes those, they were suggesting it was likely to be a strong VEI4 from initial footage). 

Edit: changed the VEI comment as think that Wiki page has been updated to say strength unknown again?

There is nothing on that link that say's it's estimated VEI however on the 2022 eruption page there is a suggestion that it could be in the magnitude of a VEI 5. It is however still very early days and I've also read this is also the largest eruption in 30 years - Pinatubo was a VEI 6

Apologies. It did, and then it didn't.

BBC's take on the eruption:

Pacific volcano: Science explains event's ferocity
https://www.bbc.co.uk/news/science-environment-60029815

Roger

Interesting seeing some of the data coming out now regarding the eruption, seems likely to have the highest number of lightning strikes of any eruption recorded. Admittedly that's limited to how long we've been able to accurately detect and record this but still impressive - I've seen figures of 200,000 + for 'the eruption' which I assume was just the 15th Jan event and 600,000 which I'd assume was including the December activity and earlier fairly large eruption on 14th Jan.  There's suggestions that the eruption column may have reached as high as 37km or so, which would again be the highest recorded although think that's TBC as there's contradictory info on that.

The global impacts are pretty astounding too, with at least one component of the Tsunami likely to be as a result of the pressure wave punching down on to the ocean - there's reports of 12cm or so waves affecting the Caribbean, which would pretty much have to have been caused by the pressure wave. It's also possible the explosive eruption itself caused or contributed, along with the possibility of a large amount of material sliding down in to the caldera or ocean floor. 

Judging by satellite pictures the 14th Jan event took out a large chunk of the newly formed bit of land between the 2 islands/caldera rim pieces and the 15th Jan looks to have taken out the remainder and a fair bit of the original islands. 

For the power of the eruption relatively small amounts of SO2 was emitted and the event itself was relatively brief, unusually so for an eruption of this size. As there's evidence from historic eruptions that the large explosive eruptions from the volcano tend to be a series of events it's possible further eruptions will occur, depending on just how much magma was expelled in this event. I guess how likely further eruptions are will be determined either by a more accurate quantification of the material ejected to compare with possible size of the magma chamber to get an idea of how much eruptive material is left, or by further eruptions occurring over the coming days. 

Clearly a tragic event for those affected, but one you can't help but find fascinating.