Massive eruption in Tonga (1 Viewer)

bjdeming

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Posted an hour ago:


Volcanoes don't necessarily stop after a "Hollywood moment." Still, whatever this was apparently wasn't as intense as yesterday's.

More information from 2017 on the volcano's history. They only really started looking into it in 2017, and this caldera does need watching. I get this general impression, from reading lots of stuff online, that the correct names for various structures might be:

  • Hunga: The mostly submarine volcano.
  • Hunga Tonga: The source of yesterday's blast. (Update: It appears to have been the caldera.)
  • Hunga Tonga-Hunga Ha'apai: The caldera that those two islands rise out of on its north rim; about 6 km wide, floor about 150 m below the waves, and not ancient, in geological terms, though the date of its last eruption is unclear.
This is a very active region, and Tonga has many unnamed submarine volcanoes; researchers number them -- Volcano 1, for instance, not far from Hunga.
 
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bjdeming

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Still reading up on volcanoes in the Tonga-Kermadec Arc, but they are reported to have a unique chemistry that reduces their SO2 output. Good thing!
 

Tennie

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Here's a couple of things that I found related to this volcano:

First, a cool video showing the shockwave from the eruption as it traveled around the world:


Next, a pretty good article about the volcano and its eruption:

 

bjdeming

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UNOSAT views of damage in Tonga (I downloaded the PDF). They also report that the caldera has collapsed! I wondered about that when it came out that the two Hunga islands still showed remnants; guess it was a caldera eruption. Hopefully, that has stabilized the system, but we'll see.

No followup on the report of another eruption. Also, Erik Klemetti guesstimates the eruption as a VEI 5, but that will get settled formally a little later on.
 
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bjdeming

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You don't realize just how helpful volcano monitoring observatories, like those run by USGS Volcanoes in the US, or PEVOLCA's work in the Canaries, are until there's a crisis in parts of the world where funding limits communications resources.

It's really hard even for experts to find out what's going on at Hunga right now (quite apart from the whole humanitarian disaster in the kingdom).

I can't find more information yet backing up/elucidating UNOSAT's report of a collapsed caldera. Did learn that Barron's did a story about a second large eruption and then killed it, so that perhaps wasn't as bad as thought.

Per New Zealand's GeoNet:

It is likely that the earlier 14 January eruption blew away part of the volcano above water, so water flowed into the extremely hot vent. This meant that the Saturday evening eruption initially occurred underwater and exploded through the ocean, causing a widespread tsunami. There are also a few other potential mechanisms that could have contributed to the tsunami. We won’t know for sure until scientists can investigate what happened at the volcano – and right now both ash clouds and limited communications with Tonga mean that we can’t be certain.

Have got to go do some other things for a while and offer these sources for up-to-date, if possible, info on eruption developments, besides the news and GVP:

  • Darwin Volcanic Ash Advisory Centre (the volcano is at Orange aviation code, not red at the moment)
  • Tonga Geological Services. Like many monitoring centers in small countries, they use Facebook. Their last post was on the 14th, but when Tonga reconnects with the world, this no doubt will be an excellent source.
 
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bjdeming

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Amazing images, and check out the cloud top temp!

Images are also emerging from Tonga, where at least three deaths are confirmed. :(

There's a lot of weird stuff about this eruption - its power, brevity, direction of the blast (I don't see obvious blast damage on the few images from Tonga released online), and cause (haven't seen anyone other than UNOSAT mention the caldera, though there was a call for doing bathymetry readings first).

This might also be the first science paper to get 1K likes on Twitter within hours of its release:

 

Tennie

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Here's a couple good articles looking at the eruption, along with a possible scenario for the cause of the explosion based on the currently available data:

 

bjdeming

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Those are interesting takes on it. I haven't seen any discussion of the supercriticality thing, but here are some thoughts on the eruption from one of the scientists who studied this volcano a few years before the blast.
 

bjdeming

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I don't know if these are significant or not. A seismologist I follow, Dr. Judith Hubbard, tweeted a few days ago that the ongoing seismicity is interesting but its meaning is unclear: could just be adjustments in the local stress field to the January 15th eruption, or something else. She did note well, I'll just include her tweet after this source (which BTW also covers tropical systems in the New Zealand area).

There was a strong quake in that general area in the last day, but closer to Fiji than to Hunga. Given the highly active and complex tectonic setting, and the weirdness of that big blast, it's really hard to know for sure what's likely to happen next. Hopefully, a whole lot of nothing and hopefully none of it has to do with Hunga.


And here's the seismologist (read whole thread):

 

bjdeming

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Massive indeed.


What concerns me is:
  1. Why? Where did the energy come from?
  2. There reportedly have been over ninety >M5 quakes there since then, including at least two today within hours of each other. Unfortunately, there isn't enough seismic monitoring equipment available to monitor this submarine volcanic situation.
 

atrainguy

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Massive indeed.


What concerns me is:
  1. Why? Where did the energy come from?
  2. There reportedly have been over ninety >M5 quakes there since then, including at least two today within hours of each other. Unfortunately, there isn't enough seismic monitoring equipment available to monitor this submarine volcanic situation.

Do the earthquakes mean a second eruption is possible soon?
 

bjdeming

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With its being a submarine volcano, and with field work only having begun recently, and only on the caldera (Hunga is a big volcano), it's hard to tell. Here are a couple articles for reference. There's also this time-limited access to a recent paper, if jargon is okay.

It seems to me that this many M5+ quakes are troubling, but then, so near that subduction zone, maybe not with something like this. There aren't many similar settings for active volcanoes to compare it with, AFAIK. Most work is done, understandably, on land volcanoes or submarine ones with easy access, like Kolumbo in Greece, near Santorini.

They need seismometers to identify the source of the seismicity, to see if its patterns show fluid movement or are tectonic (if the local stress field is adjusting after that massive explosion). Too, they need GPS stations to identify edifice uplift, if any; but they can't put any of that in place right now. Apparently there's still some surface activity over the caldera, and it's too dangerous to even do bathymetry in an attempt to figure out just what happened on the 15th.

They're even using ocean wave patterns to try to figure that out!


From what I understand of Dr. Cronin's papers, Hunga does have a history of repeat big eruptions, with smaller ones in between as magma leaks in various places up through the caldera floor. That's something to know, but it doesn't help them to predict what will happen next.

Of course, the raw power of that blast, with so very little ash in comparison, was something brand new, so there's that, too.

I hope it quiets down, but this is definitely a situation to watch.
 

bjdeming

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Photo from Reunion Island showing tropical cyclone clouds colored by hues caused by Hunga's stratospheric sulfur veil. Wow!


Also, an EGU blogger did a review post on Hunga's recent activity, filling in details about the January 15th blast and comparing it to Krakatoa 1883, which was MUCH more powerful. There is also coverage of the volcanic lightning.

On a human level, the undersea cable was repaired and Tonga is back in touch with the world. Also, they have the Omicron variant, with 254 cases per WHO as of today, but no deaths. The kingdom was COVID-free before the blast.

Still looking for more updates on the seismicity and Hunga's current status.
 

bjdeming

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New report out that offers one explanation of why the January 15th blast was so massive. The last paragraph of this news story about it is awesome:

“The volume of the eruption was not the big deal,” says geologist Frank Spera from the University of California, Santa Barbara. “What was special is how the energy of the eruption coupled to the atmosphere and oceans: a lot of the energy went into moving air and water on a global scale.”
 

bjdeming

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Well, it's official:

Based on Lamb wave amplitudes, the climactic Hunga explosion was comparable in size to that of the 1883 Krakatau eruption.

In that paper, released this week, they do note that Krakatau's 1883 Lamb pulse was about 30% longer duration. Still, they report, Hunga's eruption was an order of magnitude more intense than Mt. St. Helens, 1980.
 

bjdeming

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There's also this. They used a shallow-ocean model for the eruption's atmospheric effects!

More today about the eruption tweeted today by Dr. Cronin.

I just finished rewatching that Krakatoa docudrama, in which a world-renowned volcanologist -- Dr. Mike Rampino -- explains his theory that the 1883 blast wasn't caused by water hitting magma (Cronin's theory for the Hunga blast; check out the linked article). Instead, Rampino suggests it was magma mixing.

That's almost ten years ago, though, and I haven't been following the discussions on it.

Krakatau and Hunga are two very different volcanoes, and it's entirely possible, I suppose, that each massive blast could have a different cause.

But I suspect there's going to be a lot more debate about the specifics of Hunga's historic blast.

At least two marine teams, I have read, plan to do bathymetry studies of the caldera area. Those results won't filter out to us for a while, but maybe they will shed more light on it.
 

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