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Lewotobi volcano, Indonesia

bjdeming

bjdeming

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Hopefully the volcano won't become a huge international headliner, but reportedly a major eruption is possible and they've raised the alert to Level IV, the highest (more on their alert levels here).

It has been at Level IV off and on over past months because of various big explosive eruptions.

But I've learned a little about Indonesian volcano monitoring while reading up on Decade Volcano MErapi (Java) and have the impression that they don't use the word "major" lightly; also, a Level IV in advance of the eruption calls for mandatory evacuations and activates the whole emergency system from national down to local levels. It's a very big deal.

That, plus Lewotobi's recent blast, which was impressive though brief --



-- suggests that it might be a good idea to have a thread available rather than just scattering more posts over in the Volcano Thread.

Let's hope that it won't be needed.
 
It went off a little over an hour ago. Darwin VAAC currently reports ash to 32,000 feet. This is the only video I've found thus far:



FVAU05 ADRM 171715
VA ADVISORY
DTG: 20250817/1715Z
VAAC: DARWIN
VOLCANO: LEWOTOBI 264180
PSN: S0833 E12246
AREA: INDONESIA
SUMMIT ELEV: 1703M
ADVISORY NR: 2025/457
INFO SOURCE: CVGHM, HIMAWARI-9
AVIATION COLOUR CODE: RED
ERUPTION DETAILS: VA TO FL320 OBS AT 17/1700Z
OBS VA DTG: 17/1700Z
OBS VA CLD: SFC/FL320 S0836 E12248 - S0840 E12238 - S0831
E12235 - S0829 E12246 MOV W 15KT
FCST VA CLD +6 HR: 17/2300Z SFC/FL320 S0815 E12246 - S0857
E12253 - S0931 E12149 - S0832 E12115 - S0750 E12159
FCST VA CLD +12 HR: 18/0500Z SFC/FL320 S0839 E12232 - S0937
E12236 - S0950 E12112 - S0844 E11957 - S0722 E12046 - S0720
E12139
FCST VA CLD +18 HR: 18/1100Z SFC/FL320 S0908 E12342 - S1034
E12225 - S0821 E11848 - S0648 E11946
RMK: CVGHM REPORTED VA ERUPTION TO FL320 AT 17/1638Z. VA
OBSERVED ON LATEST SATELLITE IMAGERY. HEIGHT AND FORECAST
BASED ON GROUND REPORT, SATELLITE IMAGERY AND MODEL
GUIDANCE.
NXT ADVISORY: NO LATER THAN 20250817/1815Z=
 
CVGHM's Volcano Observatory Notice to Aviation (VONA) site, and latest report:

Eruption with volcanic ash cloud at 1638 UTC (0038 local). Best estimate of ash-cloud top is around 30669 FT (9584 M) above sea level or 25600 FT (8000 M) above summit. May be higher than what can be observed clearly. Source of height data: ground observer. Ash cloud moving from west to northwest. Volcanic ash is observed to be gray. The intensity of volcanic ash is observed to be thick..
Click to expand...

I can find nothing in the online news yet. Granted, it's the middle of the night there and people are scrambling -- we'll probably get a flood of text and images in a while.
 
I don't see anything unusual on the satellite loop (Flores is the long, narrow, roughly E-W island just northeast of the -10, -120 point on this graphic, and Lewotobi is on its eastern end; time dependent link). This could just be another big blast rather than a big eruption. Darwin VAAC's hourly reports are unchanged so far.
 
Another eruption, about 30 minutes ago, per new VONA:

Lewotobi Laki-laki - 20250817/1821Z
Emanuel Rofinus Bere, A.Md.Kom., Lewotobi Laki-laki Volcano Observatory - 27 minutes ago

Eruption with volcanic ash cloud at 1821 UTC (0221 local). Best estimate of ash-cloud top is around 30669 FT (9584 M) above sea level or 25600 FT (8000 M) above summit. May be higher than what can be observed clearly. Source of height data: ground observer. Ash cloud moving from west to northwest. Volcanic ash is observed to be gray. The intensity of volcanic ash is observed to be thick..
 
Good! They're still manning the observatory station -- I don't recall how many km away that is, but they have needed to abandon it sometimes with earlier blasts. The exclusion zone, per the last news report I've seen, is 7 km from the summit.
 
Darwin VAAC has better satellite eyes than me ;) From their 1910 advisory, which also reports two ash clouds, one at 32,000 feet and one at 26,000 feet, both moving SW:

RMK: CVGHM REPORTED VA ERUPTIONS AT 17/1638Z AND TO
17/1821Z. MULTIPLE VA EMISSIONS OBSERVED ON LATEST SATELLITE
IMAGERY. HEIGHT AND FORECAST BASED ON GROUND REPORT,
SATELLITE IMAGERY AND MODEL GUIDANCE.
NXT ADVISORY: NO LATER THAN 20250817/2010Z=
 
This layperson's knowledge of volcanism is almost nil, compared to professionals, but from the little understanding I've gotten from reading, volcanoes rarely just open up and do their worst at once, although some do -- Vesuvius in AD 79, for example (Pompeii eruption).

They can build up to a climactic event, as Pinatubo did in 1991.

Or they can just rock the neighborhood with a few blasts before returning to baseline -- a pattern for Lewotobi's earlier activity.

And what I do understand, because volcanologists note it in their papers over and over again, is that there is no reliable way to tell which path one will take after starting off.

All that the boffins can do is watch closely and try to pick up enough clues to be able to get the earliest possible warning out to everybody.

That is why, among other things, observers are out there right now on this dark and wet night, close to the erupting volcano.

PS: Just found this story (Indonesian) from the 15th, noting (browser translation) that the mountain's expansion, presumably from shallow magma accumulation, is what triggered the increased alert level.

Apparently it wants to come out but cannot yet open up a conduit. Yet.
 
Last edited:
Well, no more blasts have been reported. On the current satellite loop I can see the ash now; it's following prevailing winds, i.e., there's not a plinian cloud. (With this poor phone, it is difficult to save a GIF.)

Whatever is blocking much, if not all, of Lewotobi's throat apparently is still holding.

Darwin VAAC expects the cloud at 26,000 feet to dissipate.
 
Took a break, since the volcano was apparently taking one. Per VONAs since then, Lewotobi was subsequently quiet for about five hours and then had a blast up to around 16,000 feet.

Over the next hour, there were four more blasts, one unobserved and three reaching up to around 17, 000 - 18,000 feet.

Then there was a seven-hour pause, until 0822Z.

Over the next 50 minutes there were two low-level (~8,000-foot) events and then this:



That was at 0912Z and the plume's estimated height was about 24,000 feet. On the satellite loop it appears hefty but seems to be following the prevailing winds, i.e., not plinian yet

Darwin VAAC again reports two ash columns, one at 25,000 feet and one at around 8,000 feet from continuous emissions.

That new shallow magma really wants to escape confinement, which is still strong. I wonder how much of it is being eroded by the activity.
 
Finally found the MAGMA page, which has a still-image live cam. Currently Lewotobi is staying within the troposphere.
 
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