Posted by: magmatist | February 24, 2011

Misleading Baker eruption article in Vancouver Sun

An article on Baker eruptions appears in the February 24 Vancouver Sun. The text follows this post- you can’t read it online without a subscription. The statements about Mount Baker are badly misleading. The article quotes a UBC researcher, Mark Jellinek, and a colleague, David Bercovici from Yale University. They hope to be able to ‘predict’ an ‘overdue’ Baker eruption based on ‘wagging’, which is a type of seismic signal indicative of magma movement.  Their research appears in today’s issue of Nature. The abstract is here. Baker is not mentioned in the Science paper.

A 1 cm layer of Mount Baker BA tephra is marked by the toothpick. This is from the only verified Baker ash deposit in Canada, near Chilliwack Lake. The white layer at left is a Saint Helens ash, MSH-P, 3000 years old. Click to enlarge.

While the article may be fundamentally sound with regard to predictive ability, it is badly out of step with what is known about Baker eruptions. I hope that is more the fault of the newspaper than Jellinek and Bercovici. There are no Baker ash deposits known from the Vancouver BC area. The only Baker ash identified so far is a 1 cm layer in the vicinity of Chilliwack Lake, NE of Baker. This is the BA ash, 5740 14C years BP. As volcanic ash blows downwind, it is very unlikely that wind would carry ash to the NW of Baker all the way to the cities of the Lower Mainland, and even less likely that a ‘thick layer of fine ash’ would fall. Wind blows that direction only 4 % of the time. Further, recurrence intervals for Baker magmatic eruptions are poorly constrained. It is pretty hard to say that an eruption is ‘overdue’- the only two post glacial magmatic eruptions we know of occurred around 10,800 and again at 5740 14C years BP. While these eruptions were about 5000 years apart, it is pretty far fetched to extrapolate those two data points up to today. Yes, there was a near miss in 1975, but Baker fumarole temperatures and gas content pretty clearly show that magma is densifying beneath the mountain today, rather than getting ready to ‘blow’, as the article puts it.

A greater hazard would be a lahar coursing down the Nooksack, crossing the very low drainage divide with the Sumas River, and entering BC via Sumas and the Abbotsford area. This appears to have been the case with the last big Baker lahar, the 5900 14C BP Middle Fork lahar.

UPDATE_ I exchanged emails with Dr. Jellinek, who says he fell victim to ‘artistic license’ about his work, and that he has been ‘dealing with it’ all day.

DT

Text of Vancouver Sun Article:

24 Feb 2011 The Vancouver Sun

BY MARGARET MUNRO

Mount Baker eruption overdue: expert

Researchers are confident they can predict time of next burst

Cloaked in snow and visible across the U. S. border from Vancouver, Mount Baker looks like a gentle giant.

But volcanologist Mark Jellinek, at the University of British Columbia, says Mount Baker, located in Washington state, is probably overdue for an eruption — an explosion he and his colleagues hope to predict well in advance based on the how much “ wagging” goes on inside the volcano as magma rises up from the deep.

According to their research, to be published Thursday in the journal Nature, volcanoes shake and vibrate in distinct and predictable ways when they are going to blow because giant columns of magma “ wag” back and forth inside them.

“ It’s basically like a dog wagging its tail,” says Jellinek, except that the magma columns are up to a kilometre high.

They are so powerful they shake mountains and when they blow they can hurl hot ash up to 40 kilometres into the atmosphere, with sometimes devastating impact as the ash spreads across surrounding areas. ( Vancouver is far enough from Mount Baker it will be spared the worst effect, though Jellinek says he expects the city could be covered in a thick layer of fine ash. “ It would make a huge mess,” he says.)

It has long been known that volcanoes vibrate at pretty much the same frequency before they explode, whether they are in B. C., Alaska, the Caribbean or the Philippines. But until now no one has been able to explain why volcanoes that are so different in size and character behave in the same way.

“ Magma wagging” is the most plausible explanation yet, and may help forecast deadly eruptions, say Jellinek and David Bercovici from Yale University and co-author of the new study.

Their model of the “ magma wagging” explains why tremors in nearly all explosive volcanoes stay in a narrow band of frequencies that can be felt but are so high humans can’t hear them. Just before and during eruptions, the frequency climbs to a higher pitch, and the range spreads out.

It provides “ a fundamental mechanism for tremor that is generic to nearly all volcanically explosive systems,” the researchers report.

As Bercovici put it, the shaking is both a warning “ and a vital clue about what is going on in the belly of the beast.”

There can be weeks to months of warning before volcanoes erupt but some come to life quickly. “ The most recent eruption in the Aleutians in Alaska had five hours notice,” says Jellinek. “ But in general we do better than that.”


Responses

  1. Thanks for the comments, Dave. Let’s hope the inaccuracies indeed are with the writer of the Sun article and not with the authors of the paper in Nature.
    I too get a bit perplexed when people ask me when Mt. Baker is going to “blow.” When possible I will politely and patiently (I hope) explain that even violently-erupting volcanoes seldom “blow up,” but rather more or less “empty out” and then collapse. Reminds me of the old days of camping on an air mattress, or stories from friends back in the days of water beds, which occasionally would leak! I also assure people who ask that Bellingham isn’t likely to see more than a smidgeon of Baker ash, if that, even if Baker did erupt. But then I also like to tell about Mazama ash [Crater Lake] in virtually all of the old swamps and lakes in NW Washington (and elsewhere of course).

    • Good analogy, Doug. Blowing up isn’t a good term for scientists to use. I like the water bed analogy, having myself fallen prey to their cold, jiggly depredations against a good night’s sleep. Let’s not forget that the Mount Baker volcanic field HAS had gargantuan eruptions- Hannegan caldera at 3.72 Ma, and later the Kulshan caldera, 1.15 Ma. Both erupted over 100 times the volume of MSH 1980. So, potential is there. However, these sorts of eruptions could not be unannounced. There’d have to be YEARS if not CENTURIES of premonitory seismic activity as a large volume of magma moves into position.
      DT

  2. Hi there! Thanks for the clarification. I’m wondering what sparked the hype in the first place though? Was there some sort of shaking or wagging taking place in Baker at all?

    • Emily,
      Thanks for commenting. I have just posted (Saturday, February 26) an update that tries to explain a little bit about how all this got started. I guess the media was really reaching for something new besides ‘The Middle East uprisings’, and they didn’t bother to check with any sources outside the original story. Just because one scientist says something doesn’t mean it is correct. The media really blew it this time around, a sad state of affairs.
      Dave Tucker


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