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View Full Version : Krakatoa has erupted, looks like a VEI-6 (Larger the St Helens a little)



dgavin
2018-Dec-23, 08:20 AM
News is still coming in but like the original eruption Darwin witnessed, it caused a tsunami, and the death toll has been steadly rising the last few hours.

dgavin
2018-Dec-23, 08:34 AM
vaac: Darwin
volcano: Krakatau 262000
psn: S0606 e10525
area: Indonesia
summit elev: 813m
advisory nr: 2018/369
info source: Himawari-8

aviation colour code: Red

eruption details: Eruption to fl550 obs ext sw at 23/0740z.
obs va dtg: 23/0800z
obs va cld: Sfc/fl550 s0605 e10534 - s0625 e10528 - s0757
e10257 - s0716 e10208 - s0601 e10343 - s0540 e10524 mov sw
30kt
fcst va cld +6 hr: 23/1400z sfc/fl550 s0605 e10534 - s0638
e10523 - s0809 e10252 - s0605 e10158 - s0540 e10523
fcst va cld +12 hr: 23/2000z sfc/fl550 s0604 e10532 - s0541
e10524 - s0552 e10156 - s0737 e10231 - s0637 e10523
fcst va cld +18 hr: 24/0200z sfc/fl550 s0606 e10534 - s0637
e10523 - s0737 e10232 - s0553 e10157 - s0541 e10524
rmk: Continuous emission observed to fl550 extending
southwest, awaiting confirmation of va at ground. So2
observed on satellite imagery ext southwest at 23/0222z.
nxt advisory: No later than 20181223/1100z

Trebuchet
2018-Dec-23, 03:33 PM
News reports this morning are saying the tsunami was caused by an underwater landslide, not an earthquake. Not clear if it's connected to the eruption.

dgavin
2018-Dec-23, 06:25 PM
Eruption still ongoing, to 55,000 feet. A photographer there was caught in the tsunami, and caught the following photo (Link to his page) just before the tsunami hit.

https://www.facebook.com/photo.php?fbid=10161689033755389&set=pcb.10161689034365389&type=3&theater


It does appear to be an underwater land slide being the cause, probably related to the current large eruption.

dgavin
2018-Dec-23, 10:40 PM
The landslide confirmed, but appears to be very similar to the St. Helens event, in that about 1/3 of the western face of mountain slid into the sea. It was probably both under and above water.

https://twitter.com/CATnewsDE/status/1076848305215324160

Ash cloud is still topping 55,000 feet to SW and 25,000 to N. Spectral readings are showing it is mostly SO2/ICE and not very much ash at all. Not sure what is meant by ICE as the only place Sulfur Dioxide ice in our solar system is the planet Io.

Trebuchet
2018-Dec-24, 02:51 AM
I'd suspect they mean it's SO2 and water ice. The latter was, of course, not frozen when it was erupted but it gets cold that far up.

dgavin
2018-Dec-24, 03:50 AM
Water ice makes sense, didn't have enough coffee before posting this morning.

Image form the ISS Nasa released this morning, but it's actualy from September.

https://www.instagram.com/p/BoHL-g5DUt0/?utm_source=ig_web_copy_link

It's still hard to tell how much of a collapse there was.

I -think- from zooming in on the black and white satalite images, that the cone may have suffered a caldera collapse. It's hard to be certain but it looks like part of where the cone was might now be filled with water, and there is a new crater/cone forming in that water.

CJSF
2018-Dec-24, 04:31 AM
It would be ironic if this is a large enough and right kind of eruption to cool the planet temporarily, giving us some breathing room in reducing CO2 over a few years longer than we have. Desperate hope and not without potentially horrible trade-offs.

CJSF

dgavin
2018-Dec-24, 04:43 AM
It seems to be pumping out more S02 and Water, then ash right now. So2 is a reflective cooling gas.

Darwin VAAC is calling it a anomalous eruption. I'm not sure it qualifies as a VEI-6 anymore, but the Tsunami reached the Ural's and parts of Australia, so the land slide was fairly significant.

I suspect if the central cone had been larger, and more was above water, then there would of been a pyroclastic flow like with the 1883 eruption.

DaveC426913
2018-Dec-24, 06:14 AM
... the Tsunami reached the Ural's and parts of Australia, so the land slide was fairly significant.

Sorry, the only present day Urals I know of are a thousand miles East of Moscow. :confused:

[ EDIT ] Oh. East coast of India?

chornedsnorkack
2018-Dec-24, 12:59 PM
Sorry, the only present day Urals I know of are a thousand miles East of Moscow. :confused:


And reach to the coast of Arctic Ocean. Novaya Zemlya are a continuation.

DaveC426913
2018-Dec-24, 05:55 PM
And reach to the coast of Arctic Ocean. Novaya Zemlya are a continuation.

Sorry, are you saying the Tsunami reached all the way around the Asian continent - through the Bering Strait - to the Barents Sea?

dgavin
2018-Dec-24, 08:11 PM
Sorry, the only present day Urals I know of are a thousand miles East of Moscow. :confused:

[ EDIT ] Oh. East coast of India?

I dug back through my source for that (National Geo) and after carful picking though it, I had missed a contextual point. SO need to correct myself.

The (Seismic) waves form from the Krakatoa landslide were detected as far as the Ural's and to Western Australia. This is the text I misunderstood from their article. "But the waves didn't stop there—they traveled as far as Arti in the Russian Urals and Kambalda in Western Australia." Had to jump back a few paragraph's in the article to get to the proper context of a Seismic Wave form.

Thanks for pointing out the inaccuracy with the information!

dgavin
2018-Dec-24, 09:10 PM
Finnaly got enough information to determine that it does appear to have been a land slide combined with a lateral blast eruption. It also appears that the cone, and more like 1/2 of the island are gone.

Sat. image from 22nd showing the differences, with the area to the bottom left a bit uncertain. Source Volcano Discovery, Public Domain.

23864

Arial image from yesterday, showing that generally it looks likes more then half the island, and probably all of the cone were lost. Source Reuters, copyright
ANTARA FOTO / BISNIS INDONESIA / NURUL HIDAYAT / VIA REUTERS

23865

Squink
2018-Dec-29, 04:33 PM
BBC: Anak Krakatau: Indonesian volcano's dramatic collapse (https://www.bbc.com/news/science-environment-46707731)


They say the volcano has lost more than two-thirds of its height and volume during the past week.

Roger E. Moore
2019-Jan-03, 05:49 PM
https://www.newsweek.com/volcanoes-child-krakatoa-indonesia-tsunami-krakatau-java-sumatra-volcanology-1277215

Update from Newsweek on Anak Krakatoa, with film. Region remains highly active, earthquakes and landslides reported in wide area around.

Roger E. Moore
2019-Jan-03, 09:27 PM
WHOA - much better photographs, shocking results from cone collapse (now a bay):

https://www.bbc.com/news/science-environment-46743362

publiusr
2019-Jan-04, 07:45 PM
I wondered when we'd see the Sunda strait act up again

Video here--interesting at 1:55
https://www.youtube.com/watch?time_continue=1&v=pcwssxwy7CA

dgavin
2019-Jan-12, 07:01 AM
Still showing signs of activity. I found out a film maker was actualy there, and caught the caldera collapse on camera. Unfortunately while he escaped the tsunami his equipment did not and was lost. They don't know if it washed out to sea, or is buried in debris some place.

dgavin
2019-Jan-13, 02:51 AM
Updates finally, but not from my usual sources.


Source - Volcano Discovery:

The activity at the volcano continues at reduced rate. Steam explosions have been more intermittent and smaller during the past 2 days, generating plumes that rose a few hundred meters only.
This trend corresponds to the seismic signals showing a marked decrease since the surge of supply of magma that led to the paroxysm during 21-22 Dec, which accumulated lots of new lava. This in turn might have been "the last straw that breaks the camel's back", i.e. the additional sudden weight on the slopes and/or the shaking induced by the continuous explosions could might have been the final trigger for the landslide to occur.
The Indonesian Center for Volcanology and Geological Disaster Mitigation (PVMBG) published a first official estimate on the effects of the landslide:
- The summit of Anak Krakatau originally 338 meters high is now reduced to only 110 meters, i.e. most of the summit cone has indeed disappeared.



Source - Volcano Discovery:

The northern coast of Rakata Island, facing Anak Krakatau, was hit by massive waves (up to approx 30 m high) during the catastrophic landslide and tsunami on the evening of 22 Dec.
The entire beach and the slightly higher, up to 50 m wide forested platform behind it, separating it from the cliff, have been washed away and/or collapsed in landslides following the receding wave.

Overall even with counting the landslide and steam with the eruption ejecta; I'd say my VEI-6 estimate was woefully far to high. All told it's looking like a VEI-2 maybe close to a 3.

dgavin
2019-Feb-04, 03:26 PM
While my VEI estimate was incorrect, I did get the caldera collapse part right.

Found a good before/after image.

24001

publiusr
2019-Feb-05, 10:56 PM
Oh, if only the equipment had not been lost.

dgavin
2019-Feb-06, 05:35 PM
Oh, if only the equipment had not been lost.

I know. A lot of data was not gathered. This was probably the first Caldera Collapse type eruption in our life times, and that data could of been used to start models of seismic signals for monitoring our three super volcanoes, Yellowstone, Newberry and long valley.