Concern lingers, angers flare at Chaiten


The people who remain in Chaiten face the potential for a devasting pyroclastic flow, so says Jorge Muñoz of the SERNAGEOMIN in Chile. The volcano is still producing large ash columns on Tuesday and a flyover of the dome forming inside the caldera has lead to the concern that a collapse on a larger scale than those seen last week could wipe out the town for good.
The government hopes news like this from volcanologists might convince the last remaining residents of Chaiten to leave, but no indication of this has come to pass. In fact, things sound like they’re getting heated in the fight over the town of Chaiten. The Minister of Government Affairs had this to say to the lawyers for the remaining residents:

“I think that up until now, we have been quite convincing, but to say that the problem is to unblock the river (…) Why don’t we back up a bit? Why is the river overflowing? Because the volcano is exploding, that’s why!”

It gets even uglier here from the Undersecretary of the Interior. It seems that both sides are digging in the heels, so to speak.

Chaiten Redux


UPDATE 2/19/2009 9:45 AM: Well, it seems that my hunch was at least partially right. Reuters (and Paula Narvaez, special envoy to the Chilean president) is calling the eruption as result of “what appeared to be a partial collapse of its cone.” So, we might have seen the oversteepening of the dome growing in the Chaiten caldera that lead to a collapse, producing (likely) a pyroclastic flow and either an accompanying plinian eruption as the pressure was released or an ash column associated with the pyroclastic flow itself. Now, I might not take Reuters word for it, but it makes sense considering the suddenness of the event.
10:00 AM: More details for Reuters, including the ominous “Our security team have observed an increase in the size of a column of ash and smoke, with a deformation to one side” from the Deputy Interior Minister. My guess is he is referring to deformation on the ash column, not the volcano.
4:00 PM: From a Newsday article, just some more details on the ash dispersal: “On Thursday, increased seismic activity was reported and ash fell 100 miles (160 kilometers) away in Futaleufu.”

Eruptions reader Brian Owens has pointed out that fellow volcano follower, the Volcanism Blog, is reporting that Chaiten is experience a major rejuvenation today.
Sure enough, the Associated Press also reporting that an explosion has occurred in the main dome of Chaiten that has been built since last May and that material is moving downslope from the explosion. There is no clear word what type of volcanigenic material this might be – pyroclastic flow, lahars, avalanche – but there is a major fear that it could block the river and cause flooding in the town of Chaiten. The few citizens left in the area are being evacuated. The Patagonia Times adds that the eruption started around 11 A.M. (local time) and ash has spread across much of the region.
From what I can gather, this seems like it might have been either a dome collapse that was quickly followed by an explosion (possibly caused by the release of pressure from the collapse) or some “burp” of gas-rich magma erupting. The reports of “a massive column of ash” are interesting as this could suggest a true new flux of magma, but it is hard to tell at this point how widespread is the ash and how tall the column might be. At this point, it is all conjecture, but it sounds like Chaiten might be making a comeback. The questions woulds be how big and for how long.
I’ll update as we find out more …

Chaiten update for 2009


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?)

Interview with YVO chief Jacob Lowenstern on the Yellowstone swarm


I just wanted to point folks to an interview in US News & World Report with the USGS scientist-in-charge of the Yellowstone Volcano Observatory, Dr. Jacob Lowenstern. He plays down the swarm, noting that things like this happened in the 1980s and that Yellowstone has seen over 80 eruptions in the caldera since the last “supervolcano” eruption 640,000 years ago. I know Dr. Lowenstern pretty well, and even at AGU when I talked to him (before the swarm), he seemed to play down the huffing and puffing the caldera experiences on a yearly basis. It would take much more activity to get the YVO folks concerned about a potential new eruptive period.

Two weeks in New Zealand


Right as Yellowstone is getting interesting (or at least had signs of interest), Eruptions is going on a bit of a break again starting January 2. This time it is because I’m off to the North Island of New Zealand to do some field work. I’ll be headed to Tarawera (hopefully both the 1305 and 1886 eruption deposits), Taupo, Tongariro, the area around Rotorua and maybe even White Island (amongst other). I won’t have my MacBook, but I will have my iPod Touch, so I’ll try to keep track and make brief posts if something big comes up, but feel free to use this post as a clearinghouse for any news or articles you run across until I return on January 16th.
Happy 2009 to all the Eruptions readers!

Yellowstone New Year’s Eve Update


Yellowstone looks to be keeping everyone on their toes as we ring in 2009. The earthquake swarm reported earlier this week is continuing, with multiple events between 2-3.5 on the Richter Scale. Again, the folks monitoring the caldera – this time the Univ. of Utah – play down these events as normal for any active caldera system … and they’re very likely right. However, the media love to bring up the “supervolcano” angle and we’re even getting expert opinion from (wait for it) Garrison Keillor!.  The earthquakes are just normal earthquakes so far – none of the dreaded/anticipated harmonic tremor that might indicate an eruption. This will likely mean that more gas and water monitoring will be occurring in the park in the coming weeks/months.

Is Yellowstone making plans for 2009?


2008 is almost finished and we’ve seen one of the few high-silica rhyolite eruptions in the past 100 years at Chaiten in Chile. Chaiten was definitely not high on the list of potential locations for a rhyolite eruption worldwide. However, Yellowstone Caldera in Wyoming definitely is high of the list because it has erupted a lot of rhyolite over the last few 100,000 years (even discounting the big so-called “supervolcano” eruptions).
This is why the current news of an earthquake swarm at Yellowstone is, in the very least, really interesting. The earthquakes – over 250 of them – started yesterday and many of them were as high as magnitude 3.8 on the Richter Scale. The earthquakes are centered under Yellowstone Lake and the depth is poor constrained according to the USGS, but they appear to be shallow. Even Yellowstone expert Robert Smith (Univ. of Utah) say the swarm is “very unusual”. However, YVO plays down the event. The earthquakes might be related to hydrothermal fluids moving in the crust, they might be tectonic or they might be magma moving (but not to the surface). Definitely gives us something to keep an eye on as 2009 begins.
{Hat tip to reader Doug for pointing this out.}

Some catching up to do

panum1
I just got back from a 4 day field trip to the Long Valley Caldera in eastern California, so I’m a little behind on posting. The field trip was great and I had a chance to see a lot of pumice, a lot of welded tuff (in the form of the Bishop Tuff, the large ignimbrite that erupted from the Long Valley Caldera ~760,000 years ago) and got to lead the part that looked at the Mono domes (too bad snow covered the Inyo Domes). Pictured above some puffed obsidian – the layers are obsidian and vesicle-rich obsidian – that were erupted, cooled, expanded and cracked (known as “breadcrusting“). This is part of Panum Crater, the youngest of the Mono domes that comes in at ~600-650 years old.

CORRECTED: Erta Ale(?) erupts … and more?


In one of the most oddly worded articles I’ve seen from the BBC, a lava flow from Erta Ale an unidentified volcano in the Erte Ale range in Ethiopia has erupted a significant amount of lava. The headline states “Ethiopia volcano sets lava record”, which is strange on multiple counts, but mostly because I’m not familiar with any “lava records”, who might keep track of them and what, exactly, this “lava record” is. In fact, they don’t even mention it in the article itself. They do, however, point out that lava from this eruption has covered 300 square kilometers, which is a decent chunk of real estate, but no mention is made of how long it took to do this (or what type of lava, for that matter, but it is likely basalt). So, take this article as you will. The take home message is that Erte Ale a volcano in the Erta Ale range, near Alu, has had a significant eruption with some associated earthquakes to go along with it.
Erta Ale is located on the East African Rift in Ethiopia – part of the Erte Ale Range – and is a fairly active shield volcano that erupts basaltic lava flows from both the central vent and from fissues, along with sometimes have a lava lake in the main caldera. These eruptions aren’t too much of a danger to the people who live near the volcano as it mostly issues lava flows rather than erupting explosively. It hasn’t erupted since 1967 according to the GVP, however, the volcano did erupt in 2005 (see above), displacing thousands of people.
NEW INFORMATION (2200 Pacific Time)
Just got this email about the eruption in northern Afar, Ethiopia. Sounds like it has released a significant amount of sulfur into the atmosphere:

Satellite instruments detected an eruption in northern Afar, Ethiopia
on November 3. The eruption first manifested itself as a large sulfur
dioxide (SO2) cloud drifting eastwards over the Arabian peninsula,
detected by the Ozone Monitoring Instrument (OMI) and the Atmospheric
Infrared Sounder (AIRS). MODIS data from the University of Hawaii’s
MODVOLC hot-spot monitoring tool (
http://modis.higp.hawaii.edu)
confirmed an extensive hot-spot (presumably lava flows) near Alu
volcano, in the northern part of the Erta ‘Ale range. Details are
still sketchy and these observations are as yet unconfirmed from the
ground.

A total of 0.1-0.2 Tg of SO2 was measured in the eruption cloud by OMI
at ~1100 UT on November 4, by which time the SO2 cloud had reached
southern Iran. Using the OMI SO2 data and radiosonde soundings,
observed SO2 cloud drift yields a preliminary estimate of the eruption
onset time of 1400-1600 UT on November
3.

More details as they are available.

Volcano Profile: Rabaul

Sorry about the dearth of posts. It has been a busy week here in Davis and I’ve been a little distracted by the upcoming election. Combined with the relative lack of volcano news this week, the posting has been lackluster.
However, that being said, I will try to make up for some of it by starting my Volcano Profiles series that will bide the time between volcano news. I start with a volcano that was suggested by Eruptions reader Thomas Donlon: Rabaul.

VOLCANO PROFILE: RABAUL


 

  • Location: Papau New Guinea
  • Height: 688 m
  • Geophysical location: Boundary of Australian plate and Pacific plate, where the Pacific plate is subducting under the Australia (note: very simplified as there are a number of microplates involved as well).
  • Type: Arc-related caldera
  • Monitoring: Rabaul Volcano Observatory
  • Summary: Rabaul is an 8×14 km caldera that has been partially filled by the sea, but multiple peripheral vents can been seen along the caldera edges. Likely the caldera seen today was formed 1,400 years ago and there is evidence that an ancestral caldera formed 7,100 years ago. The volcanic system erupts basaltic through dacitic lavas from these vents, producing lava flows and voluminous pyroclastic flows that have caused extensive death and damage to the settlements near the caldera over the last 200 years. The currently active vents are Tavurvur and Vulcan.
  • Current status: The Rabaul caldera is currently in an active cycle which started in 1994, producing ash and steam eruptions, along with lava flows and ash flows from both Tavurvur and Vulcan. The caldera has been constantly active since 2006, with the most recent activity consisting of earthquake and small, conduit-clearing eruptions from a shallow reservoir.
  • Notable Recent Eruptions: The Rabaul Caldera has had two major eruptions in the past 100 years and they are stark contrasts in terms of hazard mitigation and evacuation. The eruptions from Vulcan and Tavurvur in 1937 killed more than 500 people while blanketing the countryside in ash. It also produced a tsunami that washed boats onshore. This eruption is thought to have been roughly a VEI 4. Vulcan and Tavurvur followed up this eruption with another VEI ~4 in 1994, but thanks to excellent planning, evacuating practice and an organized response, the death toll to this eruption was a mere 5 (an excellent summary of this evacuation was presented on an episode of NOVA). This eruption produced ash fall and pyroclastic flows from at least 5 vents along the caldera and the ash fall effects were amplified by heavy rain (likely caused by the eruption itself). Some of this ash was in excess of 7 feet and destroyed 80% of the structures in the town of Rabaul. Interestingly, the only real signs of a potential eruption at the Rabaul Caldera before 1994 was significant surface uplift in the caldera in the mid-1980s, followed by quiescence until the 1994 eruption.