Friday, September 17, 2004

Vulcanism Up Close

B and I just got back from Central Oregon, or Volcano Central. I’ve visited the area before, but I’d forgotten just how obvious its volcanic origins are. Most obvious, of course, are the seven big-ass volcanoes looming on the horizon, including North Sister, Middle Sister, South Sister, Mt. Bachelor, and Broken Top. (A few representative photos will be posted in an upcoming entry.)

Just about anywhere you go there is evidence of vulcanism that seems spookily recent. Look down at your feet in town or country and you might find yourself standing on a driveway made of crushed red pumice or hiking a trail littered with lava bombs and walled in by elephant-size blocks of glassy obsidian.

Living within 50 miles of two dormant volcanoes--Mt. Hood and Mt. St. Helens--you’d think I’d be a little more blasé about all the clods of pumice and pillars of obsidian strewn about the vicinity of Bend, Oregon. But the Central Oregon volcanoes seem different from "our" volcanoes. Wherever the Central Oregon volcanoes have spilled their guts, precious few plants and trees have been able to reestablish, even though they’ve had something like 7,000 years to do so! Instead there are barren expanses of chunky lava that give the impression that the eruptions must have happened roughly in the summer of 2002. This is not the case around Mt. St. Helens, which erupted only 25 years ago. Even in the “blast zone,” there is ample evidence of revegetation, which I suppose is why I just am not as aware of living in such close proximity to volcanoes.

From time to time there is talk of Mt. Hood blowing. No one can say when or to what extent. And it’s not like an eruption would entomb Portlanders in the midst of their daily routines, later to be excavated by archaeologists who would puzzle over why these people might have been drinking coffee in a bookstore or eating pizza in a movie theater. But the scenario is sobering enough. It goes something like this: If Mt. Hood were to erupt, it would spew out enough lava, ash, and rock to clog up and dam the Bull Run watershed, which is Portland’s water supply. I think that would pretty much knock Portland off the "most livable city" list.


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