Tonga Eruption

[ScottyD]

Interestingly I just had a look at a few Auckland stations and at about 3:15 this morning there are some fluctuations in pressure. It’s about the right time required for that pressure wave to travel right around the earth.

[David]

Pressure seems unusually wobbly again this morning, not sure if related though

[jamie]

Yep the wave has gone a full circle


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[ScottyD]

Pressure seems unusually wobbly again this morning, not sure if related though

I did a quick google this morning on how long it takes for sound to travel around the earth. About 32 and a half hours. So the timing is right.

[darcyplumb]

That’s amazing! When was the last time an eruption did this? I’m aware of Krakatoa in the 1800s.

[jamie]

Did pinatubo send a wave around the world?


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[Richard]

Yep the wave has gone a full circle


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Would have been interesting to have had a recording at the location where the wave meet directly on the other side of earth, but then did the Himalayas and the spine of both Americas interfere with that wave as it traveled around?

[Chris W]

Some comments this morning about the explosiveness of the eruption (currently estimated at VE5-6) including the potential cooling effect a la Pinatubo 1991:
https://www.rnz.co.nz/news/world/459657 ... -scientist

I did not hear the eruption, but the videos that emerged from Tongatapu before comms went out were very dramatic and concerning. It's good however that initial reports coming out today seem to indicate low casualty rates, albeit alongside likely significant tsunami damage and ash accumulations. Clearly there's concern from NZ and other places for aiga (family) living in Tonga and getting back in touch with them.

There was talk of a meteotsunami effect, where the pressure wave itself either triggered or enhanced tsunami activity. May be something to do with the significant tsunami waves observed on the Californian and South American coastlines. Much to unpack from this.

[Nev]

Some comments this morning about the explosiveness of the eruption (currently estimated at VE5-6) including the potential cooling effect a la Pinatubo 1991:
https://www.rnz.co.nz/news/world/459657 ... -scientist

That article says the Hunga Tonga-Hunga Haʻapai eruption's Volcanic Explosivity Index could be as high as VEI five. The 1991 Pinatubo eruption and the 1883 Krakatoa eruption both had a VEI of six, which is 10 times more powerful than a VEI five.

The USGS has a preliminary estimate equivalent to a magnitude 5.8 earthquake.
https://earthquake.usgs.gov/earthquakes ... /executive

Apparently the 1883 Krakatoa eruption's shockwaves travelled 7 times around the globe before they dissipated to immeasurable levels.

[BeaconHill]

Came across this Air Pressure chart from a Tempest weather station in Fiji.
7.2 mb swing in pressure in 30mins! (I recorded a 4.7 mb swing from peak to trough in Wellington on my Tempest)

Musket Cove Air Pressure.png

[darcyplumb]

Another eruption reported by the USGS about three hours ago. Minor compared to the other day but enough for them to issue a marine tsunami advisory for American Samoa.

[Orion]

I see the ash now drifting west towards Australia.

Satellite view:

http://satview.bom.gov.au/

[Chris W]

Some comments this morning about the explosiveness of the eruption (currently estimated at VE5-6) including the potential cooling effect a la Pinatubo 1991:
https://www.rnz.co.nz/news/world/459657 ... -scientist

That article says the Hunga Tonga-Hunga Haʻapai eruption's Volcanic Explosivity Index could be as high as VEI five. The 1991 Pinatubo eruption and the 1883 Krakatoa eruption both had a VEI of six, which is 10 times more powerful than a VEI five.

The USGS has a preliminary estimate equivalent to a magnitude 5.8 earthquake.
https://earthquake.usgs.gov/earthquakes ... /executive

Apparently the 1883 Krakatoa eruption's shockwaves travelled 7 times around the globe before they dissipated to immeasurable levels.

Just going from a few Twitter sources over the weekend, all volcanologists but making quick estimates early on. So not just that article. Going from stories of Krakatau it does seem a fair way short of that, would have to look more into Pinatubo as it's been over 15 years since I studied any volcanology at uni and I was too young to appreciate it real time when it occurred. So perhaps VE5 will be where this episode lands, but of course the real focus right now is a humanitarian one.

[Awhituobs]

From what I have read about Krakatoa, it was a beast, and beats this one by miles

[Nev]

The Volcanic Explosivity Index (VEI), used to describe the intensity of eruptions, is only a measure of the amount of material ejected, but doesn't directly indicate the intensity of the explosion itself. So Saturday's actual shock/pressure-wave might not be too far off that of Krakatoa?

[David]

I don't think this comes that close to Krakatoa myself. The explosion of Krakatoa is estimated to have been 310 decibels, and was loud enough to rupture the eardrums of sailors 60 kilometers away from the volcano.

With Krakatoa the pressure wave circling the earth 7 times before becoming undetectable is also particularly impressive. With this recent blast the initial barometer swing here was 6 hPa peak to trough and the second round of fluctuation pressure was less than 1 hPa, so probably the 3rd time will be indistinguishable from regular pressure movement.

[NZ Thunderstorm Soc]

Did pinatubo send a wave around the world?
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Not that I'm aware of but it did have a cooling effect on the planet resulting in thunderstorm development here in Canterbury in the summer.
This eruption i don't think will have same affect.

[Nev]

Came across this really informative article based on an interview with Alaska's NWS scientist, Brian Brettschneider, who says that the Hunga Tonga eruption was equivalent to just 2% of the pressure released in the Krakatoa eruption.

https://www.alaskasnewssource.com/2022/ ... e-decades/

He also explains that Krakatoa's pressure wave actually only made three and a half trips in opposing directions around the globe, which is why it was 'felt' seven times.

He also says that the tsunami waves sent around the world on Saturday [Friday in Alaska] were caused by the pressure wave, not seismic events or water displaced from portions of a volcano falling into the ocean, which explains why tsunamis were also recorded in the Atlantic.

[Awhituobs]

I did read that the tsunami recorded in the caribean , Atlanatic Ocean, arrived too fast to be an actual normal earthquake origin one
and so they surmised it was due to the pressure wave in the atmosphere
that then might explain why it was larger than expected in parts of the pacific further away.. the atmospheric pressure wave that created it was able to keep on pushing the tsunami wave under it across the pacific ocean floor for a a while after it first formed?

[Chris W]

I don't think this comes that close to Krakatoa myself. The explosion of Krakatoa is estimated to have been 310 decibels, and was loud enough to rupture the eardrums of sailors 60 kilometers away from the volcano.

With Krakatoa the pressure wave circling the earth 7 times before becoming undetectable is also particularly impressive. With this recent blast the initial barometer swing here was 6 hPa peak to trough and the second round of fluctuation pressure was less than 1 hPa, so probably the 3rd time will be indistinguishable from regular pressure movement.

You could believe that about Krakatau bursting eardrums, based on the video of the Hunga Tonga-Hunga Ha'api eruption wave coming through - the sound was very sharp and very loud indeed. Makes me wonder what Taupo would sound like, albeit only with a lake above it and not an ocean.

Great article there Nev.

[TonyT]

Makes me wonder what Taupo would sound like, albeit only with a lake above it and not an ocean.

Great article there Nev.

Bear in mind that when Taupo erupted there was a mountain above it, not a lake! We know that was heard in China.

[BeaconHill]

The article on Krakatoa and the fact sound travelled 3.5 times round the world in BOTH directions made me just click as to why I think the barometric pressure at my station in Wellington was 'noisier' than normal from 330am to 830am yesterday (Monday) morning.

With the settled weather in the last few days, pressure has not been changing much more than 0.1 0.2 mb per 5 min period, resulting in a nice smooth graph:

Normal.jpg

But yesterday morning there was a period of greater fluctuation, up to 0.4 mb in a 5 min period on a couple of occasions:

Noisy.jpg

Given the first pressure wave coming directly from the eruption took about 2.5 hours to reach Wellington, it makes me me think around 3:30am Monday, I was detecting pressure wave that set off around the world in the OTHER direction (circled in Yellow), and then 5 hours later, the first wave (having completed a full circuit of the earth) arrived again (circled in Green).

Pressure.jpg

Maybe my timings are off a bit, but incredible to see if this is the case on a personal weather station so far from the eruption itself.

And as an aside, back in school a LONG time ago, I did speech on the Krakatoa Eruption. It was something that completely fascinated me, and I can remember so there were so many amazing facts and figures. But in hindsight, at the time I personally really did not appreciate most of the stuff I presented, so to a bunch of 13yo's, it was probably boring as hell!

[tgsnoopy]

You could believe that about Krakatau bursting eardrums, based on the video of the Hunga Tonga-Hunga Ha'api eruption wave coming through - the sound was very sharp and very loud indeed. Makes me wonder what Taupo would sound like, albeit only with a lake above it and not an ocean.

Great article there Nev.

Please consider that "The Video" is not of the actual event. Same can be said of the small Tsunamis rolling in. It was the build up and early on at that. As things ramped up from there, The ash cloud turned day in to night and most residents moved to higher ground (Look and you'll find videos of this). The actual explosion proper was later in the peace & I've to date seen no video of it.

[Chris W]

The video I'm referring to is part of the main eruption.
https://twitter.com/ulumounga/status/14 ... 1096654850

[tgsnoopy]

The video I'm referring to is part of the main eruption.
https://twitter.com/ulumounga/status/14 ... 1096654850

Still early on. The ash cloud from prior eruptions turned day in to night before the big one.