Chile

I just read a report that the ash column at Chaiten is beginning to collapse. The SERNAGEOMIN says that the ash column is only 4.5 km tall now, as opposed to the 20 km it had reached earlier. Still, there are not reports of pyroclastic flows, but that could be a matter of hours or days at this point. We'll be keeping a close watch on the eruption to see if this is the beginning of the end, or just a lull in eruptive activity, here a full 12 days into the eruption. UPDATE 12:20 PM (Pacific Time): According to this new article, the SERNAGEOMIN is reporting the first of the column-collapse…
While I was looking at the gallery of Chaiten photos, I noticed another headline (in spanish) saying that the SERNAGEOMIN has issued a yellow alert for potential activity at Puyehue. Now, the "article" doesn't offer much besides pictures and maps, but apparently there has been an increase in seismic activity in the vicinity of the volcano. Puyehue is a volcano in the Andes of southern central Chile and is actually part of a complex with Cordon Caulle. Most of the eruptions in recent history (1990, 1960, 1930s) have been from Cordon Caulle, with the most recent activity at Puyehue appearing…
Here is a gallery of some ridiculously cool photos from the Chaiten eruption ...  
Before we get too far, I wanted to make sure that folks understand that I'm just making educated conjectures on the nature of the eruptions I read about and by no means do I have any extra insight over those scientists on the ground at the eruption. I have a very limited set of data to examine - whatever the media reports - so I am just speculating based on what I know about the eruption style, volcano in question and whatever other variables might come into play. So, please, don't think that I know exactly what is going on or what will happen better than the scientists tackling the volcano…
This marks a full week of eruption at Chaiten and the volcano shows no signs of abating. You have to feel for Luis Lara. He is apparently the pointman for the SERNAGEOMIN in regards to this eruption and really, I think its anybody's guess what might happen next. Heck, we haven't seen many eruptions of this scale - and this out-of-the-blue - since the birth of modern volcanology, so we're testing a lot of hypotheses now. What Dr. Lara says is that the eruption is still going strong, lava flows seem to be occurring at/near the vent but not spilling out of the caldera, the two vents have…
Another day, another development at Chaiten. Military stationed near the volcano helping with evacuations reported "booming noises" and saw incandescent blocks getting hurled from the vent area. This suggests that lava is at the surface and potentially that the edifice itself is beginning to crack/strain from the loss of material from the eruption. Remember, when you erupt all this volcanic material, you leave a void under the volcano where that magma used to be, so suddenly you have a volcano with no foundation. Sometimes they can founder into that space, forming a caldera. We already…
The eruption at Chaiten has now begun to have widescale effects on the region of Patagonia, beyond the ashfall. Air travel has been disrupted due to the amount of ash in the air. It is well-documented that ash posed a significant hazard to aircraft, so this seems like a wise move on the parts of Argentina and Chile.  Not much else new to report beyond that the fact that this eruption is now into day 6 without any signs of letting up. Impressive to say the least.
NASA captured this great image of the ash plume from Chaiten, which has reached 15-km into the atmosphere. Following this eruption, I'm sure there will be a lot of work into why no one had any clue an eruption of this magnitude was about to occur.
Well, this is getting rather harrowing. Volcan Chaiten, the Chilean volcano that sprung back to life last Friday after anywhere between 2,000 to 7,000 of quiet, is apparently erupting lava along with ash now. Sounds like its a good rhyolite/rhyodacite lava based on the description: "very small and very thick and as such was moving slowly so it is moving very slowly''. Chilean officials are now fearing that the volcano is in "worst case scenario" mode - although, they never mention what that might be: full-on caldera? topography-erasing ignimbrite? Pinatubo-scale eruption? However, the…
Monsters and Critics has some truly fabulous images of the ongoing eruption at Chaiten in Chile. The pictures of the extent of ash fall are quite remarkable. It is hard to tell exactly how deep the ash is or how far from the vent these pictures were taken, but one can imagine that if a helicopter took them, then they are relatively far from the action. The Chilean President, Michelle Bachelet, toured the area to see the damage. Stunning stuff.
Update 5/4/08: Looks like there is now officially a deathtoll for Chaiten, as an elderly woman died during the evacuations. The volcanoes continues to spew ash and I wouldn't be surprised if it did so for at least a few more days. There have also been reports of a sharp increase in earthquakes in the area since the eruption. Now, before everyone goes nuts, this could be just a response to the dramatic release of pressure caused by the eruption, possibly faulting in the caldera walls activated by the eruption, or possibly magma working its way to the surface as the eruption progresses.…
Update 5/3/08: SERNAGEOMIN (the Chilean Geologic Survey) is now concerned that the eruption of Chaiten may be a the precursor of a larger eruption, mostly owing to the long (~9,000 year?) repose time. This could be the beginnings of a southern Andean Pinatubo. The towns around Chaiten are more or less deserted now as the volcano continues to spew ash and pumice - upwards of 15 cm of ash in some places. Edit: fixed link (thanks Mark) Edit 2: fixed date of last eruption from ~7,000 years ago to ~9,000 years ago.
The big eruption news today is an unexpected eruption in southern Chile. In fact, it is so unexpected that depending on when and where you read about it, you might get a different answer to what volcano is doing the eruption. What we do know at this point is an eruptive column has been spotted by people on the ground and the Washington VAAC, with estimates of an eruptive column height of between 35-55,000 feet. In other words: pretty darn sizeable. Ash is also coming down in town to the east of the eruption in Argentina. Now it seems that Chilean officials say Volcan Chaiten is the culprit…