Tourist warned to stay away from Chaiten

i-0f6c80ecdcfb50e31bedb1740f90efd7-Chaiten-thumb-400x254-41163.jpg
The rhyolite domes of Chaiten in Chile in an undated photo. Note how much of the previous Chaiten Caldera has already been filled by the new domes that started after Chaiten erupted in May 2008.

CNN International has a report that the National Emergency Office (ONEMI) in Chile has reinforced the "red alert" status of Chaiten (spanish). The volcano, which has been erupting since May 2008, had recently settled down to slow, but constant, dome growth. However, over the last 3 weeks, seismicity has been increasing at the rhyolite caldera, suggesting that we might be heading towards an upswing of eruptive activity. Now, the volcano has been at a high alert status since it started erupting almost 2 years ago, but the relative calm has caused hundreds of tourists to decide it is safe to approach the volcano (spanish) - and this reissuing of the red alert was a response to this. So, the ONEMI is telling you tourist: stay away! Chaiten is still very active and could potentially produce ash falls, pyroclastic flows or lahars. You can check out what is happening at Chaiten on the rim webcam (which today looks like either its rainy or endtimes) or the more distance webcam at the Chaiten airfield.

And if you are interested in Chilean volcanoes, Llaima has also been placed on "yellow" alert status after signs of increasing seismicity (spanish). However, this is the tourist season in southern Chile, so local officials have already called the change of status "hasty" and may keep tourists away - a claim the national government denies.

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Chaiten rim webcam giving great picture of raindrops and not much else, that'll put off these foolhardy tourists better than any official warning.

(At Lonquimay's 'Navidad' eruption the Chilean Army had to be called in to keep swarms of onlookers at a safe distance from the cone)

It is clearing up, a better view of the dome now. It will be interesting to hear a more technical report. Besides incresing seismic activity (and more details there would help too), is there more gas being emitted? Is the rate of dome growth changing? Hopefully SERNAGEOMIN will update soon.

Magnitude 6.7 - CHINA-RUSSIA-NORTH KOREA BORDER REGION
2010 February 18 01:13:17 UTC
Versión en Español
DetailsSummaryMapsScientific & TechnicalTsunami Earthquake Details
Magnitude 6.7
Date-Time Thursday, February 18, 2010 at 01:13:17 UTC
Thursday, February 18, 2010 at 10:13:17 AM at epicenter
Time of Earthquake in other Time Zones

Location 42.561°N, 130.836°E
Depth 562.5 km (349.5 miles) set by location program
Region CHINA-RUSSIA-NORTH KOREA BORDER REGION
Distances 110 km (70 miles) NE of Chongjin, North Korea
110 km (70 miles) SW of Vladivostok, Russia
580 km (360 miles) NE of PYONGYANG, North Korea
1080 km (670 miles) NW of TOKYO, Japan

Location Uncertainty Error estimate not available
Parameters NST= 80, Nph= 84, Dmin=670.1 km, Rmss=0 sec, Gp= 43°,
M-type=teleseismic moment magnitude (Mw), Version=6
Source USGS National Earthquake Information Service, Golden, Colorado, USA

Event ID us2010swaf

A clarification (google translation): The alert for Chaitén volcano is issued from OVDAS (Observatorio Vulcanológico de los Andes del Sur) related to SERNAGEOMIN, not the ONEMI. It is like you say that FEMA declared red alert for Redoubt, and not the AVO.

By Guillermo (not verified) on 17 Feb 2010 #permalink

My two cents....

Is there any chance Chaiten may erupt explosively again like it did un May 2008?

This eruption has been going on for almost 2 years now. I really whonder what will happen as the magma chamber will get exhausted... caldera collapse? How many km3 of rhyolite have been erupted until now?

Has there been any recent analysis of the lava erupted for the last weeks? If what I believe is correct, the eruption will tap into deeper and deeper layers of magma into the chamber, and the lava will go less and less silicic, less and less evolved... and the eruption style may change accordingly.

If the magma chamber is filling up with fresh basaltic magma from the subduction zone, at the same rate rhyolite is drawn from it to build the dome, some basalt or mixed silicic/basic lava will eventually make it to the surface and things could start to get interesting...

I apologize for my broken English, I'm French...

By Volcanophile (not verified) on 18 Feb 2010 #permalink

@Volcanophile: chances that there will be an eruption the same size as the May 2008 event at Chaitén are at best remote. Usually one cataclysmic eruption comes alone. And consider that the volume of magma extruded by this eruption (I guess it's little more than 1 km3 - if at all - thus far) probably represents a minuscule fraction of the whole amount of magma in the reservoir, it is not likely that there will be any significant void left that could collapse. Rather, the magma is constantly replenished - look at Montserrat where a dome is building since 1995, and Santa Maria-Santiaguito (Guatemala) whose lava dome is growing constantly since 1922. It is not the slow extraction of magma that will lead to magma chamber emptying and collapse.
But you're asking another interesting question, about the assumption that the magma reservoir is replenished with mafic magma, will this mafic magma some day reach the surface? At Mount St. Helens it did some 2000 years ago. At most volcanoes, for some reason, it don't, or it comes only as small blobs enclosed in silicic magma. So I would not count on seeing Chaitén producing rivers of fluid, yellow-orange colored lava flows like those we see on Hawaii anytime soon.

@Randall: I just checked the quake info on USGS and they upgraded that quake on the China-Russia-NKorea border to a 6.9. The depth is something else! That may have been a good thing for the people in the area, depending.

@Boris: there sure is something going on at Reykjanes! Is that were Surtsey came up or was that more to the south east? I am just wondering what is in that area that would start to quake like that. I know it has to do with the Mid-Atlantic ridge, but what is right below there? Another situation like Surtsey? I guess we will see. It is definitely an area to watch. Thanks for posting the info.

@Diane: Reykjanes IS the Mid-Atlantic Ridge diving down into the sea offshore southwestern Iceland. Surtsey lies further east, let's say pretty much south of Iceland, not far from Heimaey where an eruption in 1973 threatened the most important fishing port of the country and aroused my personal interest in volcanism. Both Surtsey and Heimaey belong to a group of islands called Vestmannaeyjar (Westman) Islands, and they are supposed to lie on a newly opening, southward propagating rift arm that might one day substitute the current main rift at the Reykjanes Ridge.
I hope this is understandable. And yes, it would be nice to see an island-building eruption there, I think the last one on the Reykjanes Ridge was in 1783 (the same year of the great and devastating Laki eruption in Iceland)!

@Diane: Reykjanes IS the Mid-Atlantic Ridge diving down into the sea offshore southwestern Iceland. Surtsey lies further east, let's say pretty much south of Iceland, not far from Heimaey where an eruption in 1973 threatened the most important fishing port of the country and aroused my personal interest in volcanism. Both Surtsey and Heimaey belong to a group of islands called Vestmannaeyjar (Westman) Islands, and they are supposed to lie on a newly opening, southward propagating rift arm that might one day substitute the current main rift at the Reykjanes Ridge.
I hope this is understandable. And yes, it would be nice to see an island-building eruption there, I think the last one on the Reykjanes Ridge was in 1783 (the same year of the great and devastating Laki eruption in Iceland)!
As a matter of fact, in the past few weeks there's been a lot of seismic activity scattered all over the tectonically and volcanically active areas of Iceland.
At present, though it seems as if the seismic activity on the Reykjanes Ridge were a bit subsiding.

Boris, when was the last significant volcanic activity in Iceland? I know there was activity at GrÃmsvötn in '04.
Maybe someday when the volcanic news is slow Erik can recount the events of the '73 eruption on Heimaey for the readers out there (hint, hint).

Yes, the most recent eruption in Iceland was in November 2004 at GrÃmsvötn. So a new eruption would not be that much surprising.
Oh yes, a nice Heimaey special in this blog would be absolutely suitable. That was one particular event, because it was immensely interwoven with human life, and since that was the first eruption that I followed (at the time via newspapers and television), I started immediately seeing eruptions as events strongly related to humans and their activity. I just wonder what mediatic effect the same eruption would have today ... but I really don't wish anything similar to happen anyplace where humans live, because even an eruption with a happy end is traumatic for those who lose their homes in it, who have to evacuate in the dark of night.

@Boris, thanks for informing me about Reykjanes Ridge. I thought it was part of the Mid Atlantic Ridge. I just wasn't sure about where it came in contact with Iceland. I figures Surtsey was east or south east of Iceland.

Am I reading you right when you said Reykjanes is subducting below Iceland? I thought it was splitting Iceland apart. I am not getting the connection here. According to what Erik says above, the entire system of Iceland is complicated. Can a construction ridge subduct at the same time it is supposedly contructing?

I understand about the part of Surtsey and Heimaey being part of another arm developing and possibly taking over from Reykjanes. I think undersea ridges can form just about anywhere if the conditions are right, as I also believe that some volcanoes that are considered extinct are really not. I may be wrong here, but I also think that some volcanoes that erupted only once and emptied the magma chamber can erupt again if another chamber developes under it again. I am aware of such areas like CA that has had some volcanic activity that is supposed to be extinct and because of the Sierra Batholith, cannot erupt again. I do have my doubts about that simply because, while we know a lot of what is happening, we don't know the whole story. Your thoughts on this would be appreciated very much. I have a lot of respect for you! Thank you for your contributions.

@Diane, Boris didn't mean subducting, I think he just meant that the surface expression of the MOR ridge just drops down to its customary height, way below sea level south of Iceland the further away you get from the hot-spot.

The volcanic province is fascinating though in that it extends so far to the East i.e. in the direction that the hot spot is moving!! They must have been some seriously massive lava flows to get that distance from the MOR / hot spot.

By bruce stout (not verified) on 18 Feb 2010 #permalink

@Bruce, thanks for clarifying that. I think I am getting the picture now. And it seems like the ridge just goes right up onto the island. I saw a program that talked about that and how it is splitting the island. The man that was showing the ridge was walking in it and mentioned the eruption that created that part of the ridge. Right now it is a deep trench. I wish I could visit Island, and a lot of other places, too!

Speaking of lahars, I love that video of a landslide in Italy. The ground simply slips and appears to turn fluid. Lahars are pretty much the same except they are mostly sand - add enough water and it starts to flow (and encourages more sand to flow). Lahar flows have been clocked at pretty high speeds (above 80km/h) so they're really good at tearing up anything in their path.

By MadScientist (not verified) on 20 Feb 2010 #permalink

Chaiten caldera-rim webcam seems to be stuck still showing the pic from Feb 22 17.57.31

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