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La Soufriere St. Vincent volcano may erupt big time (2 Viewers)

bjdeming

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Then again, it may not. They're not taking any chances, though -- its eruptions can be very explosive and this Caribbean island offers few safe places -- and they called an evacuation of the red zone (northern half of the island) about three hours ago.

This is the volcano that sprouted a cute little "donut" earlier in the year.


Lava_dome_La_Soufriere_during_2020-2021_eruption.png


Remember that?

This is what the volcanologists tweeted a few hours ago:



Big change from its earlier slow growth. Also the seismicity has changed, and there are other worrisome signs. La Soufriere can be incredibly violent, so they've taken action. It's not exploding yet, but if it does, and with that dome plugging the conduit, it might be major, as in 1902.

Here's a post I did on this volcano and am updating as possible. It contains background as well as links to authoritative sources. Unfortunately there don't seem to be any public cams, though experts have it monitored.

This is probably your best bet for reliable, up-to-date information on the crisis.
 
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bjdeming

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Yep.


They got many of the 16,000 people living in the red zone out before it blew at 8:41 a.m., local time. Lots are still there, but the government reportedly is going to try overland evac, and maybe the volcano will cooperate by either quieting down or holding off escalation for a bit.

Dang, though. That little lava donut was a cutie. It's long gone now.
 

bjdeming

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At the end, you'll see a second major eruption. That apparently was the start of ongoing major explosiveness. Here's the multiple-part latest scientific update tweetfrom UWI-SRC, with a nice shot of volcanic lightning.


What eventually happens next in these eruptions is fluctuating pressures at the vent, causing pyroclastic flows and surges. But this is still in an early stage.

Here's the hazard map (and source, if you're into the nerdy stuff ). They're trying to get everybody clear of the orange zone, too, per NEMO earlier today.

feart-06-00042-g004.jpg
 
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Matthew70

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How will this affect wx here if any? Will Hurricane season be affected? Are there other volcanoes on the islands? If are I would expect more to erupt in coming years.
 

MNTornadoGuy

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How will this affect wx here if any? Will Hurricane season be affected? Are there other volcanoes on the islands? If are I would expect more to erupt in coming years.
No this eruption isn't big enough. There are volcanoes on the other islands but just because this one erupts doesn't mean there will be a chain-reaction or something.
 

bjdeming

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How will this affect wx here if any? Will Hurricane season be affected? Are there other volcanoes on the islands? If are I would expect more to erupt in coming years.

Good answer above. Also, all parts of the mainland US aren't close enough to be affected the way other Lesser Antilles islands are now.

I'm not qualified to recognize a Plinian-style eruption, so let's leave that for the boffins over time; this certainly is VERY powerful, even for Caribbean volcanoes, but ? if it can be called Plinian or subplinian. Those really big events are just about the only ones, AFAIK, capable on entraining enough air to loft volcanic gases (sulfurous ones are the main culprits) up into the stratosphere, where global climate and regional weather patterns might be affected.

Might.

Mount St. Helens in 1980 went Plinian, and AFAIK there weren't weather or climate changes (of course, lack of today's observation technology back then must be considered, too). Pinatubo in 1991 did change things. Sulfur content matters, as does the volcano's latitude, the season -- oh, it's complicated!

Tropical weather this year will cause lahars as well as the usual destruction, but it won't be affected by this or other typical local blasts.

As for the other islands, most of them are simply a single volcano or volcanic range sticking up out of the sea. Some are more complex: in that paper I linked to earlier, Dr. Richard Robinson -- the hero of the day right now on St. Vincent (and probable object of abuse if the magma had stalled and froze in place, as it very well could have) -- anyway, he notes that little Domenica has nine active vents!

Plate tectonics is the reason. But each volcano is unique.

Just before La Soufriere went off, UWI-SRC tweeted an answer to somebody's question about the definitely eerie fact that La Soufriere and two other nearby volcanos went off around the same time (within days of each other) in 1902, and now all three are restless. No ifs, ands, or buts were expressed in that tweet! Each volcano has its own magma chamber and acts independently of the others.

Anyway, just wanted to share a couple of views this morning from northern St. Vincent, where the volcano is:


And from the southern end, in the green zone:


Sorry about the double-up. I only copied URLs for the night look in mid-morning and her narration of poor visibility around Kingstown.

No updates from UWI-SRC or NEMO yet, but they report that both red and orange zones are cleared, though obviously somd are staying in the danger zone. I wouldn't.

Good thing most have evacuated. This is a bad eruption. So many lives will be changed forever by it.

Here's a UN report from January for background on, among other things, St. Vincent's vulnerabilities. Beside the pandemic, they've apparently got a dengue fever outbreak, too. And for some reason they can't use social distancing in the shelters, as Indonesia is doing during the Mount Merapi crisis there. Sigh.
 
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bjdeming

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Using Geosphere, I can see the shockwaves spreading out, including over the Grenadines to the south.
 

bjdeming

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Per the national radio this afternoon, there is a water crisis because of ash. Getting potable water is a challenge on these islands anyway, but they've had to shut down all intake systems since yesterday and can only distribute what had been collected and treated before the eruption. If possible, they may be able to get water turned on for a couple hours a day or truck it in to some locations; that's the best scenario, I think, and in the future. Right now it sounds like everyone is on their own (and, hopefully, heeded instructions to fill up before things blew up yesterday: ten gallons per person per day for five days was recommended).

The things we fortunate people take for granted...

P.S.: TV stream (not live right now).
 

bjdeming

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A double-up again, sorry.

But speaking of Owia, that is up on the northern shore, I think. Before the 1902 eruption, the area used to be called Carib Country after the natives whose remnant people lived there (yes, the Caribbean is named after them). After 1902, the Caribs were gone. Those who didn't flee to other places had vanished in the pyroclastic flows.

So these people are smart. The "volcano chaser" and sailors are taking a big risk. No one knows when the flows will start this time around, and they travel fast.
 
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bjdeming

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And it's certainly putting out sulfur, too:


That's a model. I saw a quote around midday today from Simon Carn that an estimated 0.4 teragrams (400,000 metric tons) of SO2 had been erupted thus far.

Of course, that's not in the stratosphere, I assume, but combined with the amazing explosiveness today, now I'm wondering if there will be climatic effects.

Edit: Here we go. Wish I could find reliable estimates of today's plume heights.

 
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bjdeming

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Yeah, and it's still going on. Current ash advisory puts the observed ash cloud at 40,000 feet. I don't know how that correlates with maximum plume height, but since the tropopause is so high here, even 13° north of the equator, and given the ways winds are influencing the plume, this layperson speculates that very little material is reaching the stratosphere.

That 40,000-foot report is the maximum altitude and also consistent since 0059 UTC.

NEMO reports a country-wide blackout since yesterday afternoon's big blast and even more ominously:


Note, though, that only the activity pattern is said to be similar to the VEI 4 eruption in 1902. Looking over Andersen and Flett's old report, and comparing ash amounts to pictures from the Belmont Observatory a few miles from the volcano showing smaller quantities, this may be less intense than 1902. SVG needs all the breaks it can get at this point, and I hope that is true: nothing more than VEI 3.

Lahars will be bad, come hurricane season, but it could have been worse: in 1902, there were two crater lakes that drained.

Anyway, some people define Plinian as VEI 5 (probably not correctly, per what I've read of the controversy about the term in volcanology papers), so despite the high sulfur content, global climate effects from stratospheric sulfur aerosols are likely to be none to minimal.
 
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bjdeming

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This volcano is to continue eruptions for weeks maybe months they are saying.
The director of UWI-SRC just said in a Barbados press conference (the start is delayed, but the director comes on right after the PM) that this explosive phase might go on for days to weeks. :(

This:


Technically, of course, the eruption has been going on since December and on the whole could continue for months to years.
 
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