Chaiten eruption still going strong

As fall descends on the northern hemisphere, spring starts in the southern. Luckily for us, it means that we get better views of the southern Andes in Chile ... which means the NASA EO could train one of the many "eyes in the sky" (specifically the EO-1) on Chaiten. The volcano is still erupting, going on 16 months, since it caught everyone off guard in May of 2008. As you can tell from the image (linked and below), Chaiten is slowly filling in the pre-2008 caldera with new rhyolite dome growth - you can see that the pre-2008 dome within the caldera (see the picture taken from the ISS in 2003) was much smaller in both height and volume than the recent image. Also, you can see the amount of volcaniclastic material that has been driven down the channel of the Rio Chaiten (in the enlarged image) into the bay near the (former) town of Chaiten. The eruption is currently producing 1.5-2.5 km / 6,000-8,000 ash-and-steam plumes accompanying by periodic dome-collapse pyroclastic flows that sweep down the dome. Remember, you can always watch the action on the many Chaiten webcams.

I can't say enough about the importance of this Chaiten eruption. We have never been able to so closely watch the development of rhyolite domes like we have at Chaiten. To see the volcano slowly heal the caldera with new rhyolite over the course of years can now give us new insights into the longevity of these magmatic systems, the rates of rhyolite generation and the size of reservoirs that this type of volcano might have. Just merely being able to see how the dome grows and at what rates is exciting enough (for a volcanophile like myself). At this point, no one wants to guess how long this eruption might continues - months? years? decades? There (PDF link) has already been a bounty of scientific literature produced on the eruption, as well. It is a fascinating eruption that should be considered one of the most important over the last 500 years.

Chaiten volcano continuing to erupt in late September 2009 and fill the pre-2008 caldera with 2 new rhyolite domes. See an enlarged image here. Image courtesy of the NASA Earth Observatory.

Chaiten Volcano (foreground) and Chaiten (town) background in Chile, taken from the ISS in 2003.

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What do you suppose has happened directly due west of the volcano (towards Santa Barbara the coastal town). It looks like the land is still scorched and devoid of vegetation. The previous images from March don't show that much destruction in those regions deep in Parque Pumalin. Did we have a pyroclastic event over the austral winter that was undocumented? Flowing towards Santa Barbara (the future Chaiten) and not the real town??

By Melissa Lowman (not verified) on 29 Sep 2009 #permalink

@ Melissa: I noticed that too, but I think it's just snow, partially melted, on the top of the nearby mountains. A pyroclastic flow would have left many more damages, and on a broader area.

Here's something totally unscientific, but weird: Chaiten report made me realise that a remarkable number of major / notorious / just plain interesting volcanic events have happened between the end of April and mid-June. El Chichon, Chaiten, St Helens, Pelee (and St Vincent)1902, Tambora, Anatuahan, Pagan 1981, Novarupta/Katmai, Pinatubo, Okataina (Tarawera),,and the 2nd Century AD Taupo eruption was about this time of year too. And both Krakatau 1883 and the Grimsvotn (Laki) eruptions started in that period although the climax came later. OK major events can happen at any time of year, it should be a random distribution. It's just odd.

what a great image! we haven't had one for months, no flybys by the Chilean authorities, nothing. That certainly looks like a lot of dead vegetation to me towards the east. Not necessarily any one PF, just continued daily bombardment of ash, I expect.

What's also interesting to me is seeing how the dome is taking on more and more the shape of Tarawera with a large skirt of scree surrounding the dome. It will certainly be interesting to see how long the eruption continues.

By bruce stout (not verified) on 30 Sep 2009 #permalink