View Full Version : Chaiten Volcano update

05-06-2009, 06:01 PM


3. Conclusions and interpretation

The eruption continues in the same form, with a continuing growth in the dome complex, which appear to occupy the entirety of the interior of ChaitÚn. Although the seismic activity reported to date has shown a slight decline in the number of HB-type earthquakes, their magnitudes have reached 4.5. Consistent with the reported seismicity, the RSAM seismic energy released has also maintained its values, a phenomenon that is related to the increase in the growth of the dome complex. In consequence, it is possible that explosions and block-and-ash flows could occur, which could affect the valleys adjacent to ChaitÚn volcano.

Considering that the eruptive activity continues with a high rate of growth of the domes and high seismic activity, SERNAGEOMIN maintains Volcanic Red Alert.




Second, another belated report from ChaitÚn, covering the period April 22-28, released by the Chilean government with its usual lethargy, and translated by the fluent Dr. Harrington. Of particular note, the extreme seismicity continues, only slightly reduced from its mid-April peak. Dome building is now taking place throughout the caldera, which is brim-full and spilling over. The dome has attained a width of 2.5 km. I imagine its volume must be considerable. If it is every pulverized by explosive eruption, the world will be looking at a very big cloud. No one knows what will happen here. This is an unprecedented event.


09-03-2009, 09:49 PM

ChaitÚn Update
volcanoes by seablogger

Caught up in other concerns, I only just got round to my first look of the day at ChaitÚn volcano. Usually I check early to see if there’s any hope of fair weather, and come back later if conditions look promising — which they rarely do. I was quite startled when I logged into a perfectly clear afternoon, and I was astonished by what I saw — a nearly vapor-free plume in the dry weather, emanating from both eruptive zones on a much broadened dome complex. This has been one busy volcano during the long concealment in fog and storm. But no one knows or cares, other than a few locals, and elsewhere, a handful of geology buffs who know this unprecedented phenomenon could herald the greatest eruption in human history.
4:18 PM, Thursday, 3 Sep 09 |

Comment by Helen

Thursday, 3 Sep 09 @ 6:46 PM

“greatest eruption in human history”
It was interest Chaiten that led me here and I know it has grave possibilities, but I wasn’t quite prepared for the above statement. Could you expound on why you think that?

Comment by seablogger

Thursday, 3 Sep 09 @ 7:30 PM

In geologic terns, there have not been any major eruptions in human history, Krakatau was just a puff, compared to bigger rarer outbursts like prehistoric Toba.

The initial earthquake pattern implied Chaiten might have a magma chamber 30 km in diameter. That’s big enough for something horrendous, if it should blow.

Comment by Chad

Thursday, 3 Sep 09 @ 8:11 PM

Alan’s quite right. The ultra-Plinian eruptions (Yellowstone, Mammoth, Toba, etc) haven’t occurred in civilization’s history. Such events are actually quite frequent in geologic history and possess power beyond the scope of what humans have yet witnessed.

And I’d rather not see it.

09-03-2009, 11:01 PM
I just did a quick review of what's readily available on the current eruption. This is not a very big volcano, and its caldera isn't very big either. It's not Yellowstone- sized, it's Crater Lake-sized. It is currently dome-building, probably triggered by magma being squeezed up like toothpaste by subduction under the Andes. The geologists are comparing it to Little Glass Mountain in the Modoc Plateau. I've walked on Little Glass Mountain, it isn't very big. The next volcano over is ten times its size. This is not adding up to the potential for a monster eruption like Pinatubo, it's nowhere near that big a volcano. And Pinatubo was nowhere near the size of Yellowstone or Mammoth.

I didn't find anything in the *professional* literature saying it could create the biggest eruption in human history, I think someone just made that up.

09-03-2009, 11:10 PM
The initial earthquake pattern implied Chaiten might have a magma chamber 30 km in diameter. That’s big enough for something horrendous, if it should blow.

Really? I haven't heard that. That sounds like an order of magnitude off, which means 1000x less volume. Pinatubo was a sub-10km3 size event and I believe this one would be as well. Enough aerosols to cool the globe 1/2 C or so for a year, but nothing more than that. Would such for the people around it though. I hope for their sake it never happens.

Mama Alanna
09-04-2009, 08:54 PM

Ought Six
09-07-2009, 09:39 PM
The 2008 Chatien eruption produced rhyolitic magma, the first eruption to do so in nearly a century. Rhyolitic magma has a higher water content, and can produce more explosive eruptions. Rhyolitic magma also remains plastic at lower temperatures, making it more active for longer than basaltic magma as it cools. This makes a large magma chamber forming under this volcano a matter of even greater concern.