Sakurajima 2023 (March 24 1744 UTC)

  • Alert level: 3
  • Japan Meteorological Agency (JMA) Sakurajima portal
  • Zaiho Cam B:

  • Latest official status update (autotranslated)

March 24, 2023, 10:44 a.m., Pacific: Good news in today’s official update (via Google Translate):

 According to the tiltmeter and extensometer installed on the island, the gradual crustal movement indicating the expansion of the volcanic edifice, which had been observed since around January, has mostly stopped since around mid-March.

Let’s wait and see if this pause continues.

March 13, 2023, 12:17 p.m., Pacific: No change in alert status. However, monitoring agencies are issuing updates every few days, and on checking the cam just now, I noted what might be very faint glow in Showa (or possibly just an incandescent ballistic fragment nearby or a local vegetation fire caused by hot material) — this is within the alert range of activity, but also 😎.

And the current update has this good news:

According to the inclinometer and extensometer installed on the island, the gradual crustal movement indicating the expansion of the mountain body, which had been observed since around January, has slowed down since around February.

It’s ongoing, presumably, but not so fast.

Update, March 6, 2023, 10:57 a.m., Pacific: The tweet says it all. Per JMA today, alert level is still 3.

Update, March 3, 2023, 8:57 a.m., Pacific: From today’s JMA update (emphasis added):

…Six eruptions occurred at the Minamidake summit crater, three of which were explosions. The volcanic plume rose up to 1,600m above the crater rim, and large volcanic blocks scattered in a trajectory reached up to the fifth station (1,000m to 1,300m from the Minamidake summit crater).
 Very small eruptions occasionally occurred at the Showa crater.

 At the Minamidake summit crater, we observed the glow of volcanic eruptions with a high-sensitivity surveillance camera at night throughout the period. No glow was observed at the Showa crater.

 During the field survey conducted during the night of February 28, we continued to confirm geothermal areas on the southeast flank of Minamidake and near the Showa crater. In addition, according to the field survey conducted yesterday (2nd), the amount of volcanic gas (sulfur dioxide) released was 3,500 tons per day (previous February 20, 3,500 tons), which is extremely high.
 A few volcanic earthquakes have passed. Volcanic tremors associated with eruptions have been observed.
 According to the inclinometer and extensometer installed on the island, the gradual crustal movement indicating the expansion of the mountain body, which had been observed since around January, has slowed down since around February….

So, they’re keeping it at level 3. To this layperson, it sounds as though the venting through two craters now might be relieving internal pressures on the edifice, though with those geothermal areas near the active craters pointing to a shallow heat source, this eruption is likely to go on for a while.

The best news, IMO, continues to be that Sakurajima’s ultimate magma source — Aira Caldera — appears to have stalled its resupply for a year now.

Update, February 24, 2023, 2:40 a.m., Pacific: They did an overflight on the 21st (presumably after the big blast from Minamidake, shown in the last update below):

An aerial observation conducted on the 21st with the cooperation of the 1st Air Group of the Maritime Self-Defense Force confirmed that a white volcanic plume was rising from the crater wall on the north side of Showa Crater. Compared to the previous observation (October 12, 2022), the amount of volcanic smoke from the Showa crater increased. No particular changes were observed in the Minamidake summit crater and its surroundings.

The edifice continues to inflate, they note.

Update, February 21, 2023, 4:07 p.m., Pacific: Sakurajima put some muscle into today’s blast, with video of it saved and shared by Zaiho, but it was still a single vulcanian eruption.

Alert level is unchanged, and the current JMA update at their site is dated February 20th.

Update, February 16, 2023, 12:57 p.m., Pacific: I see no new updates or change in status from JMA — just wanted to share the video of that impressive blast from Minimadake on the 14th (it’s currently night there; the cam shows some crater oncandescence).

Update, February 13, 2023, 5:32 p.m., Pacific: No changes, but it’s interesting that, per JMA’s update today, Showa Crater is quiet (it has a gas plume, though, in the current cam view); Minimadake Crater, which shows a thicker plume on the cam just now, has gone back into business with a couple of eruptions; and the volcanic edifice continues inflating.

Sakurajima is in Aira Caldera, which underlies part of Kagoshima Bay, but the caldera inflation has been stalled for quite a while now, according to JMA. This activity, I think, seems to be only in Sakurajima itself.

Original post

Today the volcano unplugged (presumably) Showa, one of its three summit craters, with an eruption.

I’m still looking for online videos of the event.

Also, JMA reports that the complex stratovolcano has been swelling a bit since January 14th.

Rather than continue the earlier post, with all its updates from last year, here is a new one.

This is only a lay opinion, but this possibly was a very good thing. Unlike many volcanoes, Sakurajima tends to have “big ones” through flank fissures. I assume that rising magma has been pressurizing the edifice since January 14th, and today the plug at Showa Crater gave way before the flanks did.

My question now: Will the pressurization continue or was this enough relief for things to revert back to a vulcanian style?

Featured image: Wikimedia, CC BY-SA 4.0

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