Monday Mulligans

It has been rather quiet on the volcano-front in the last week. Redoubt and Llaima (in spanish), after a few weeks of intense eruption, are both back on Orange Alert. News of the eruptions from Hunga Tonga Hunga Ha'apai and Fernandina is rather sparse in the details. The news of volcanism in 2009 seems to have settled down.

A few tidbits I caught over the weekend:


Damage wrought by the eruption of Chaiten on the town of Chaiten in Chile, taken in early December 2008. Image courtesy of the NASA Earth Observatory.

Don't you feel like you're read this sort of story before after other disasters: Government commissions the university experts to study and report on a plan to fix things after a disaster, only to ignore the findings and do their own thing? Well, that is what the Chilean government seems to be doing with the town of Chaiten (in spanish), which was made unlivable by the continuing eruption of the volcano of the same name. The controversy actually does not have much to do with the volcanism, but rather the nature (public or private) of the land being used to relocate the city. If any readers have a better grasp of the Chilean and local politics involved, feel free to chime in.

I'm linking to this fluff travel piece from the Nashua Telegraph mostly for the excellent photo of the ocean entry of a Kilauea lava flow, showing tourists gawking at some impressive explosions. That and I can understand the desire to visit Hawai'i if you've just coming out of the winter in New England.

Don't get me wrong, I'm all for wildlife, but pretty much every article about the Galapagos I've read in the last few days have only talked about the effect on wildlife and left much to be desired about the volcanism. I guess the science journalism folks know what gets people reading, and that is cute animals, not basaltic fissure eruptions.


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I guess the science journalism folks know what gets people reading, and that is cute animals, not basaltic fissure eruptions.

Maybe if journalists point out the benefits of volcanic soil to coffee drinkers (Columbia = volcanic soil = coffee) caffine addicts will sit up and take notice.

Dr. Klemetti, do you know of a before photo of Chaiten? If you showed this current photo side by side with a before photo, people may appreciate the change. The expansion of the coast line and the river channel moving through town instead of along side town may become more apparent. Thanks.

Great photo from AP! certainly worth of the link.

Erik, do you have any take on the RSAM plot from Chaiten that has got all us non-professionals in such a tizz?

Even apart from Chaiten, I am sure I am not the only one who'd appreciate any pointers you could give us on the signifcance of seismic signals and RSAM plots. I know they are still very much in their infancy as a tool and the recent Redoubt series is a good case in point, with the volcano ramping up into full eruption very quickly after a number of "false" starts.

Are there any RSAM plots that make a distinction between the different types of signal (tremor, hybrid, volcanic-tectonic etc.) and would this teach us anything?

(I'll say thanks in advance and keep my fingers extra doubly crossed that you have the time to reply ;-) )

to patrick:

from memory, I think Alan Sullivan might have done something like that at his excellent blog which covers among other things volcanos:

notwithstanding the huge amount of sediment dumped in the harbor, I suspect some of the effect may be due to tides (i.e. the after photo may have been shot at low tide, exaggerating the effect).

Regarding Patrick's question about Chaitén 'before and after', there doesn't seem to be any satellite image of the town before the eruption comparable in detail to the ones that have been obtained since. There's a post comparing Formosat images from May 2008 and December 2008 (the latter being the picture Erik has used above) at The Volcanism Blog, from 17 December last year:

There was always a river channel through the town as well as to the south. It's hugely widened now, with destruction on either side.

Bruce S.'s point about tides is interesting. The NASA Earth Observatory page for the 19 May 2008 image states that it was acquired at low tide, but they don't say anything about the December image: (May 2008) (December 2008)

I suspect *both* images were captured at low tide, but I'm open to correction.

- Ralph


great pictures of the Redoubt dome from the hut camera today. any bets on how long the waterfall will last before it gets buried?

Bruce - Regarding the RSAM, I have to admit they are relatively new to me as well. Based on what I've read, they are more or less a way of looking at how every 10 minutes (or whatever time packet you choose) of seismicity (specifically, the amplitude of shaking) compared to the last packet. So, if you have lots of events that blur the overall trend, you can see the overall trend by averaging the events and scoring the amplitude of the events against each other. I don't think you can see differentiate different types of quakes using RSAM (I could be wrong but the USGS does warn The RSAM does not differentiate between volcanic activity and other sources of ground vibration such as wind, someone walking nearby, or a large regional earthquake. Thus one must be careful to not mistake wind noise or other non-volcanic signals for volcanic activity. RSAM works best during times of high activity when the volcanic signal dwarfs most noise.), so you're really just getting a picture of how the shaking changes over time. As for Chaiten, it is obvious that things are getting busier (You can see the RSAM for Chaiten here, thanks to the Volcanism Blog), so either the eruption is increasing in intensity - and at this point, this would be faster dome growth caused by increased magmatic influx, or possibly by increased degassing of the magma as it ascends. Or, at least, that is my take on it.

Thanks Erik! Very much appreciated!
I fell into that signal to noise ratio problem last year trying to keep daily tabs on Ngauruhoe (which is currently very quiet). Your comment on Chaiten raises more questions for me: if the quakes are caused by magma rising in the existing conduit, why then have they "all" shifted to west of the volcano (they used to be focused on the southeast)? and does your comment on greater degassing suggest a possible increase in the gas content of the magma?

Also a sincere apology to Ralph: it was the volcanism blog that ran the comparison I was thinking of. Sorry about that and thanks for correcting me!!

We can't see what is going on under the ground.
But, maybe there is a small chance that the earthquakes that are in a different location near Chaiten may indicate a different pool of magma may rise up.

So, there is a small chance that the characteristics of this eruption could change if the makeup of the rising magma changes.

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