14 February 2012

[OR_liff] Mount Hood Is Good … Boringly Good

2781I've declared my love unending for that beautiful Multnomah Indian maiden sitting on our eastern horizon, Mount Hood, or Wy'east, as the original natives called her. She gives Portland a backdrop that other cities would kill for (I know, I've asked Jacksonville, Florida). Smooth in profile on the south, rugged (but not too rugged) on the north, the mountain, the highest one in Oregon, seems to reflect beatifically upon the city that looks back with a highly-photographed, come-hither expression.

Of course, she's one of the Cascade Range's famous sleeping giants, who could (and have) erupted violently enough to lay waste to multiple square miles and throw entire states into darkness before noon. It's like living with a gorgeous killer next door, a femme fatale like no other.

Or is it?

I was transfixed by an article in The Big O that attempts to explain Hood's comparative quiescence. While Rainier sits in majesty, intimidating Seattle and threatening to unleash lahars as far west as Puyallup if they get any more uppity, Hood hangs out in the distance like a mellow fellow traveller, at ease with her surroundings.

It turns out that Mount Hood is good … boringly good.

After analyzing crystals embedded in lava from relatively recent eruptions, the researchers found that hot magma from deep below Mount Hood consistently mixes with cooler, mushier magma nearer the top weeks to months before an eruption.  
The heating makes the magma less viscous, or more runny. Potentially explosive gases can harmlessly escape the thinner mixture -- think of the bubbles that stream to the surface when you open a can of soda, Koleszar said.  
And that prevents a high-powered explosion that blows the mountain's top. 
The entire article at OLive is here: http://www.oregonlive.com/environment/index.ssf/2012/02/mount_hood_unraveling_the_myst.html.

Bottom line here, a so-called "Plinian" eruption … which is what Saint Helens had, and what almost every other volcanic mountain can expect to have at one time or another, is, through the chance of the process described above, extremely un-likely to ever happen with Mount Hood.

That's not to say, of course, that an eruption at Hood wouldn't cause some level of catastrophe. And lahars … mud, ice and rock flows that can scour out a river valley … are still a likely thing with our peak. Actually a lahar can happen because of an out-wash of glacial ice or an avalanche, not necessarily triggered by volcanic activity at all. So wariness of the volcano next-door is not to be discouraged.

But it is reassuring to know that the Mount Hood we're familiar with isn't likely to change much even if she erupts, and moreover, we know why.

The geologic province that the eastern reaches of Portland is embedded in is named for a pioneer community that's received a lot of ribbing over the years for being Boring.

Turns out, majestic Hood is the most boring volcanic of them all. 


stan said...

Oh, great, now there's scientific evidence saying why Wy'East is so docile. Don't those vulcanologists realize that that's the kiss of death? Tell a mountain that she's tame and she'll get mad and prove you wrong.

Expect an eruption by year's end.

Samuel Klein said...

Maybe they were getting bored. Or maybe they just wanted to get a rise out of her.