Volcano thread (3 Viewers)

bjdeming

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It's amazing to watch, but this is what Sakurajima used to do: one-off vulcanian shots and you were fine as long as you stayed out of the summit exclusion zone.

They knew they were in no danger, and they see hundreds of those pops every year.

That changed over this past weekend, unfortunately.

See how it keeps coming this time?


The volcano has switched to continuous explosive behavior for the last three days and evacuations are underway on the peninsula and, I think, in parts of Kagoshima City.

You can't tell that from the live cam: there's an unusual number of boats in the bay currently (at sunset).



This Decade Volcano is in a complex setting that includes a large submerged caldera, and the quickest way to explain that is with this post/book chapter. Am not beating my own drum here -- it's just the easiest way to describe why this is a particularly dangerous situation, though per the Japan Times at present, authorities aren't expecting a repeat of the 1914 catastrophe.

Time will tell.

PS: Actually, if you are inclined to buy my DV eBook, thank you and a BIG thanks to everyone who has bought it, but if you hold off for a month or so (no later than mid-September, hopefully), you'll get the much more in-depth second edition that I'm working on now.
 
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bjdeming

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Many thanks to Hunga Tonga, presumably, for the extended twilight glow; sunset was actually at 7:18 pm!

I've been making every allowance for weather and ash in the air, and still see something on Sakurajima's flank that doesn't shift around:

20220726_060508.jpg

This volcano has a nasty history of flank eruptions, but there is absolutely no mention of a concern about that online, AFAIK, and it would show up on monitors beforehand -- deformation, seismicity, etc.

Am thinking that's probably a forest fire started by some of the big lava bombs from the blast on the 24th.
 

bjdeming

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No changes noted in today's update, but they're keeping Sakurajima at Level 5.

With all three summit vents now open, I think it all comes down to how pressurized the magma chamber is. That's miles underground, beyond monitoring range.

The good news: It's always better to have an open conduit, especially at explosive volcanoes, so there no plug to build up pressure behind.

Here's what might be a more reliable live stream:

 

bjdeming

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Update: They've dropped to Level 3 per the current update.

That's a big relief, although Sakurajima is still in a new mode, as very slight incandescence showed on the cam overnight.

Much better a lava eruption than escalation into something resembling 1914. Hopefully that will be the only result of this round.
 

bjdeming

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Here's another live cam:


Sakurajima is not (yet) going back to its previous vulcanian mode, but it hasn't intensified, either (yet).

The alert level is still 3, but on August 5th, JMA wrote:

There is a risk of eruptions accompanied by large volcanic blocks or small pyroclastic flows over 1 km from the Minamidake summit crater and Showa crater.

So it's still wait-and-see, without evacuations at the moment AFAIK.

Edit: Finally found the "A" cam! :)

 
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bjdeming

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Well, this is spectacular. Still a vulcanian explosion, but much more powerful than those of the "soccer-game" era. Nice lightning, too. No new updates from JMA.

 

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