Many thanks to Mike Ross (@eruptionchaser) who pointed out Sakurajima on March, 29, 2015 with the following comment:
Heads-up for Sakurajima everyone.
Average 450 eruptions a year. So far in 2015, over 300 eruptions.
31 eruptions on March 27th alone. I’ve been watching the webcam:
Deformation/swelling/inflation has been reported.
This is potentially shaping up to be something biggish. Raw data (in Japanese) from JMA: http://www.data.jma.go.jp/svd/vois/data/tokyo/STOCK/volinfo/gensho.html
(This report from my own observations and from a contact in Japan)
Webcams can be found here:
Sakurajima is a composite stratovolcano that occupies a peninsula sitting on the Aira Caldera in Kyushu, Japan. It sits within 10 km of Kagoshima, capital city of Kagoshima Prefecture. Kagoshima is populated with over 680,000 people.
The volcano has three peaks, one of which is active, and tops out at just over 1,100 m above the bay. It has been in near continuous eruption since 1955 with hundreds of explosions yearly.
Eruptions are typically explosive, with significant ash and debris. Most of them are Strombolian, VEI 1 in intensity, sending plumes some 4 – 5 km into the air. There are regular ash advisories issued by the Japanese Meteorological Agency notifying residents and aviation of ash hazards.
There appear to be two magma sources, one an andesitic (dacite) source near the center of the Aira Caldera, and the basaltic source much deeper.
The current eruption series started off with a bang in 1955 with a Vulcanian VEI 3 eruption. Before that time, Sakurajima erupted every few years, with increasing frequency in more recent years.
The largest historic eruptions of Sakurajima took place in 1471 – 76 and 1914. The earlier eruption was a VEI 5 while the 1914 eruption was a VEI 4. The 1914 eruption connected Sakurajima Island to the mainland via a peninsula built of ash and lava.
Sakurajima is the active expression of the Aira Caldera, which measures some 17 x 23 km in diameter. It was formed around 22,000 years ago in a VEI 7 eruption that deposited some 400 km3 of tephra and pyroclastic flows on the region. Ash from this eruption has been found over 1,000 km from the vent.
The eruption took place in two phases. It began with a Plinian phase that ejected some 100 km3 of tephra. It was closely followed by a massive series of pyroclastic flows that deposited the rest of the 400 km3 total. The vent for both eruptions was at the current site of Sakurajima Volcano. There were at least three additional caldera forming eruptions out of Aira over the last 300,000 years.
The most recent caldera forming eruption produced primarily rhyolite. The cause appears to be a large rhyolitic magma body that was destabilized by an intrusion of basalt from underneath. We saw this sort of thing with the Katmai – Novarupta eruption of 1912. This contrasts with earlier andesitic / andesitic-basaltic eruptions out of Aira. Current activity at Sakurajima is also andesitic in nature.
Volcanic activity in Kyushu is primarily driven by the subduction of the Philippine Plate under the Amurian Plate. There is a spreading center beginning in central Kyushu extending southeast into the Pacific Ocean. The interaction of the spreading center and the subduction of the Philippine Plate has been sufficient to provide enough melt and crustal weakness to trigger what in my mind has been a caldera outbreak in southern Kyushu and south into the Pacific.
Cbus wrote an article about the five calderas of Kyushu in 2013. It is an excellent introduction to caldera activity on and near Kyushu. You can find it here. https://volcanocafe.wordpress.com/2013/07/22/southern-japan-calderas/
If Mike and his contacts are correct, things may be on the verge of getting more than a little interesting at Sakurajima. This is a very dangerous volcano which has gone caldera several times in the not so recent past. There is no reason to believe it is finished.
http://www.jma.go.jp/jma/ (Japanese language)
Thanks agimarc and Mike for reminding us! Although most of us have got sort of “used” to the almost continuous eruptions of Sakurajima, we should not forget that this volcano is one of the most interesting/dangerous/beautiful on Earth and is still capable of surprising us all in a more or less or even very little enjoyable fashion!
The weather in southern Kyushu has been horrible for the last weeks and not much could be seen of Sakurajima. Yet, yesterday I sat down in front of my webcam page with the determination to catch some activity no matter how long I would have to wait – it was no longer than 10 minutes until I was able to capture this image, through all the fog and vog billowing around the crater
So, I guess, there is a lot going on, hope the weather will be clearing up a bit soon. I can’t say what the webcam is called, probably Sabo xxx cam, it’s one of the many on this page: http://www.qsr.mlit.go.jp/osumi/camera_sabo.htm (Google doesn’t translate the page for me). On my webcam page it is Cam No. 9 of the four live cameras. http://volcams.malinpebbles.com/pubweb/Japan2.htm The Kyoto camera (SVO 2 on my page) showed it too, but very faint, unfortunately it is not light sensitive enough for small eruptions at night.
Aaand… a new batch of NtV images is up, hopefully you find them somewhat easier! 🙂
Howdy all – asked AVO about the activity at Augustine over the weekend. Turns out there was no activity. Text of their e-mail follows:
And the AVO contact form is here: http://www.avo.alaska.edu/contact.php
They are pretty good about responding quickly to queries. Cheers –
Very nice of them to answer.
Indeed it is, most times these days it goes like this…
Hello, thank you for calling the Emergency Volcanic Event Contact Center, please choose one of the following options.
To report a bit of a wobble on a seismo in your area please press 1.
Press 2 for reports of ash fall or funny smells and you’re sure it isn’t your husband
To report an imminent threat of eruption press 3
If you are about to be engulfed in a pyroclastic flow from a VEI8 please redial on 0800 YR-FKINDEAD-ALRDY
To hear these options again, press 11, thank you.
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Interestingly, there has been inflation over the last few decades at the Wakamiko caldera, in the Northeast corner of the Aira caldera, beneath the bay. This is the site of a previous caldera forming eruption, and will almost certainly be the site of a future eruption. This could be devastating for Kirishima, and perhaps the entire Kagoshima prefecture, depending on how bad it is. 1.7 million live in the prefecture.
This area is probably one of the highest-risk areas in the world based off population density and the propensity for a volcanic disaster (along with Italy and a few other areas). Where did you see information about the inflation in Wakamiko? Do you have any links?
Some small explosion at Ubinas
Click to access reporte_ubinas_201515.pdf
some nice pics at the end
Wow, look at the heicorders now! It’s a different station than that which was shown in the report, though, probably nearer to the crater.
Edit: There is a second report already, about high tremor going on for 14 hours
Click to access reporte_ubinas_201516.pdf
TV news video (24 Horas, Peru) of the Ubinas eruption. This must be a horribly ashy affair! Some villages in the 5 km zone have been evacuated.
Some activity near Hekla, Iceland. Is She on the go?
What sort, earthquakes, tremor? Sorry, right now I can’t look it up myself, have to leave shortly. But what I have learnt about Hekla, she is never on the go, if anything, she is on the RUN! 😀
Four quakes 10 km south of Hekla this morning. between 3 and 4 km down. Nothing remarkable on tremor graph.. On the run? Well, maybe just turning around for some more sleep?
Vatnjofull more than Hekla proper.
Just for the beauty of it, Etna in her morning glory!
from http://www.guide-etna.com/webcam/# (but the colour is gone now)
Sakurajima update: I’ve just been speaking to a friend in Japan, who has relatives in Kagoshima. They state that even locals, who live with the volcano and are usually very blasé about it, are becoming distinctly concerned. Inflation is continuing quite strongly, I’m told, and I’m trying to get more details – where exactly, how much, maybe an interferogram. Volcanologists are being fairly restrained and tight-lipped, in public at least, so far.
Visual observations at the webcam have been difficult due to the weather over the last few days, but during those times when visibility has existed, the volcano has been in virtually continuous eruption.
Thanks mike – please keep us up to date. SakuraJima / Aira is a volcano that warrants lots of concern.
And just as a reference to other readers, Sakurajima has been nearing the level of inflation it had before the early 1900’s VEI-4 eruption, and that was prior to this current level of inflation (which we’re still awaiting details). Many volcanologists are expecting a decent sized explosive eruption of Sakurajima within the next 50 or so years as a result of the ongoing inflation as well as the overall history of the volcano.
And while the frequent explosions are fun to watch on the webcam, they are not particularly large or productive. I believe the cumulative ejecta from the explosions over the past 4-5 years it not even equivalent to a VEI-2 eruption in total, so while it is degassing slightly, there isn’t as much pressure being relieved as you would perhaps think.
Before the VEI-4 eruption in the early 1900’s, there was a lot of rapid inflation that occurred, as well as some significant earthquakes. If Sakurajima decides it wants to do more than the daily puff, it will likely become readily obvious without needing to be a volcanologist that something is “up” at the volcano.
As for me, I find the southern Kyushu region of volcanism one of the most interesting areas in the world. It’s an area that is a developing volcanic rift in a subduction zone, with a history of large-scale caldera volcanism. And while the 5-6 caldera eruptions that have occurred have been huge, current evidence suggests that the Kagoshima graben region could still be in its infancy overall.
The region as a whole is actually very comparable to the Taupo Volcanic Zone. They’re both active extensional regions in a subduction arc, with very thin crust, and very similar extension rates (7-8 mm/yr). Additionally, many believe slab rollback is occurring in these zones, which creates conditions for large-scale silicic volcanism.
Call me morbid, but the thought that some time in the geological future, the people of Kyushu WILL undergo a massive volcanic disaster is a little surreal. If you lived in a city that had 10,000 nuclear warheads buried beneath the ground with a timer set to detonate at an undisclosed time within the next 5000-10,000 years, would you still choose to live there?
Given, 10,000 years is a long period of time (and just a very rough gauge), but it’s still a weird thought, akin to knowing the future inevitable cause of your own death, just not knowing when it will occur.
Just a little bit curious about the 1914 eruption; what was the evidence of inflation there? I’m not saying it didn’t happen, but instrumentation was much less advanced then -no recourse to GPS systems, for one thing- and it would surely have had to have been on a fairly large scale (like St Helens?) to be noticeable
Yes, it was similar to St. Helens. I’m going off memory right now, but I believe there were a few large earthquakes, and the shoreline around the volcano became noticeably uplifted prior to eruption.
Okay, I understand it’s fairly normal and in the range of more or less energetic continuous activity, but it’s still impressive to see these almost constant outbreaks, and for sure it;s a constant nuisance to the people in the area.
Kyoto cam at 20.42 UTC.
Lending weight to ebus05.s comment, it’s noticeable that the cone around Showa crater hasn’t grown dramatically in the years it has been going…come to that, the main cone didn’t see much growth despite continuous activity since 1955…
Is there a connection or is this just tinfoiling?
Just tinfoiling 🙂
Tinfoiling, yes. But worse are the reasons for the mass killing, see this article from 2013:
According to Jon’s blog deflation at Bardarbunga has stopped and activity is slowing down in the new hydrothermal vents that formed due to the recent activity.
I guess that means the show is over for now, at least at Bardarbunga. Makes me wonder what is going to happen next. 😀
Just thought I’d mention this here as well. 🙂
New Post is up!