It is hard to believe that the eruption at seem to come out of nowhere at Chaiten started over 8 months ago now, and apparently is still not showing many signs of abating. I did get a chance to see some great talks and posters at AGU last month about the Chaiten eruption, with the key points I took away being that Chaiten is erupting a very crystal poor rhyolite (<1% crystals) and that it seems that the source of the magma is relatively deep in the Andean crust. Also, there are some indications that the eruption at Chaiten may have been tectonically instigated – i.e., that earthquakes in the area might have helped the magma to erupt – at least that is what Luis Lara of the SERNAGEOMIN believes (hat tip to Thomas Donlon for the link). The eruption at Chaiten also wreaked more havoc on aviation in South America than we thought, effecting airports 1000s of kilometers away and almost bringing down a number of aircraft. Most everyone I talked to seems to think what we are seeing is very similar to what happened at Little Glass Mountain in California about 1,000 years ago.
Moreover, the eruption hasn’t really stopped since it began in May of 2008. In fact, just last week we saw a collapse of part of the new dome that have produced some pyroclastic flows within and outside the caldera (see above and the Volcanism Blog) and fed more ash into the choked rivers near the volcano. It is anyone’s guess (well, at least at AGU) how long this eruption might go on – weeks? months? years? – but the consensus is that this might be a once-in-a-lifetime eruption (but we already knew that, didn’t we?)
13 responses to “Chaiten update for 2009”
-
-
-
There are a whole string of Volcanoes sited along the Sumatera fault in Indonesia. Krakatau lies above a sharp bend in the border of two subduction plates.
Anecdotally, the local people on Nias island just off Sumatera and mainland people tell of an earthqake and tsunami around 1880. There is also anecdotal talk of a earthquake on the Sumateran Fault on the island not long after. Again there is evidence and anecdotal knowledge of at least one Sumateran Volcano (Sibayak) not long after this (1881). Sibayak is very close to the run of the Sumateran fault line. And of course in 1883 Krakatau.
I know that Mike Rampino has suggested that the Krakatau eruption might be linked to a tectonic event. He had some evidence of this.
Interestingly the people of Nias Island have handed down knowledge that tells them to run for the hills after a major earthquake in case of a Tsunami. Also interestingly the fatality level on Nias was very small compared to the west coast of Aceh after the Dec 2004 Mag 9.0 -
Well, I’ll tell you I was surprised by Dr. Lara’s conclusions, but Chaiten is definitely in a unique tectonic setting. There are a lot of complex geometries at play around that part of the southern Andes, so the storage and eruption of silicic magmas due to these forces might be most apparently near Chaiten and volcanoes around it. Sounds like there will be a lot of work to be done to examine this interplay of tectonism and magmatism.
Recent posts
Quote of the week
“It’s not far-fetched that almost everywhere in the world where you have volcanoes you have mythologies or new gods being created.”
~ Werner Herzog
Eruptions 
Leave a comment