Sinabung Update for 9/1/2010

Now that I have dispensed with the pleasantries, we can get back to volcanoes!

The volcano that many of you have been following is still Sinabung in Indonesia. After a couple days of minor explosive activity over the weekend, the volcano appears to have simmered down some – at least according to reports from the Indonesian Volcanology and Geological Disaster Mitigation Agency. However, Suruno, the head of the Agency, will be keeping the evacuation order in place as they try to assess what the volcano’s activity might be next. He described the recent activity as “[an] eruption of just volcanic ash and not lava flow, not much glowing material, it is not very dangerous for the life”, which to me suggests that it was, indeed, a “throat-clearing” event that mostly erupted older volcanic material in the volcanic conduit or vent area. You can see some AP video of the eruption – along with a pretty scathing report on the lack of preparedness of the Indonesian Volcanology and Geological Disaster Mitigation Agency for this eruption. CBS News also posted some more images of the volcano erupting that make the glow at the flank vent crater pretty obvious (see below) – magma is near the surface.

Sinabung erupting on August 31, 2010.

Many of the over 21,000 evacuees, nevertheless, are returning to their homes near the volcano (but outside the 6-km exclusion zone) even though there is no assurance that Sinabung is done. Hopefully this will not become a pattern – small explosions that prompt evacuations followed by quiet – because if a larger eruption occurs, it could become more difficult to get an effective evacuation (nothing like a volcano that cries “wolf”). The Indonesia government will continue to operate shelters while the evacuation order stands – which could be for another one to two weeks, depending on what Sinabung decides to do.

You can see a great NASA Earth Observatory image of Sinabung before the eruption, including its location relative to the Toba caldera if you click on the image to see the larger version. In that large version, the Toba caldera is peeking out on the lower right hand corner of the shot (and an impressive fault trace on the left-hand side). It is remarkable to see how populated the area around Sinabung and Toba is right now.