Inch by inch, Cascades bulge getting bigger

Portland Oregonian | 10/24/01 | MICHAEL MILSTEIN and Richard L. Hill

[holyscroller]

Bubble, bubble, toil and trouble ...at least for the people downhill. Not if, but when is the question.

[Hans Moleman]

Something's cooking.

[Mr. K]

I thought we settled this before... it was caused by Barbi Benton click here

[rockfish59]

stop it! i'm 20 miles (as the crow flies) from mt. rainier, and a la-har-har-har is not funny!

[Landru]

Years ago I lived near Mt Lassen National Park, in northern CA.

If you get to the summit of Mt. Lassen, you'll gaze into a crater which has to be 20 miles across.
The plaque says that at that point the mountain used to extend another several miles upwards & did so until it blew its top several millinia ago.
That, along with the small quakes one felt living in that region made me anxious to move back to the relative safety of the good ol' midwest.

[LeeMcCoy]

"Only one small earthquake -- a magnitude 1.9 on Aug. 21 -- has been detected in the area."

It would be much better if there were a number of small earthquakes occuring in the area. This is not a good sign.

[b4its2late]

Uh oh.

[jimtorr]

It would be a shame for a volcanoe to erupt west of the S. Sister. That is an incredibly beautiful area. Access is reasonably good, with Oregon hwy 242 running through the middle of it.

This is one region that has profited from the creation of nearby wilderness areas and roadless areas. It's only about 50 miles east of Eugene, and by the late 1970's was being badly damaged by overuse.

Of course, like many conservation policies, things have been taken to an extreme. You need to get a permit from the U.S. Ranger Station to walk on any of the extensive network of trails, for example. All campgrounds and most of the parking has been eliminated.

Ah, well. Volcanic action is what created much of the beauty, I guess.

[skeeter]

An underground infusion of about 30 million cubic yards of molten rock could have caused the swelling, but that's less than one-tenth as much as Mount St. Helens ejected in 1980.

I didn't think Mt St Helens ejected magma, only pyroclastic materials.

[John H K]

It would be much better if there were a number of small earthquakes occuring in the area. This is not a good sign.

Nope, not true at all..volcanic or magma-induced seismicity is a LOT different from tectonic seismicity.

Lots of small quakes (particularly "harmonic tremor") would be a sign that magma was REALLY moving and a ZILLION small harmonic tremors is a sign of an impending eruption.

No quakes is never an ominous sign when you're talking volcanic activity. It's not really a question of needing small quakes to relieve pressure. The absence of small quakes indicates there can't be all that much pressure.

[John H K]

Well, technically, no volcano ever ejects magma...once it's on the surface, it's lava. But the ash that Mt. St. Helens ejected WAS magma until it got very close to the surface..hence, you can compare what Mt. St. Helens ejected with unerupted magma chambers at other volcanoes.

[SuziQ]

It's only about 50 miles east of Eugene, and by the late 1970's was being badly damaged by overuse.

Well any damage man did by overuse is going to look real puny compared to what will happen when the Sister blows her top! But as we learned with Mt. St. Helens, the Earth is very resilient and will heal itself rather quickly.

[ericthecurdog]

Perhaps it has something to do with this...

[ValerieUSA]

Mt Lassen had a good-sized eruption in 1915. It has only been quiet since 1921.

[ValerieUSA]

Mt. St. Helens, 1981

[ValerieUSA]

The gigantic fault line running through Portland could let a loose with a BIG earthquake at any time. It is noticeable by eye, and one of the freeways runs right next to it - yet geologists made an announcement about their "discovery" of it less than 10 years ago.

[js1138]

Someday Yellowstone will blow again and we will all stop worrying about anthrax.

[Landru]

Yea.
But I read that plaque over 25 years ago

Aside from my lousy comprehension?
When I was a kid, 1915 probably seemed like a, "few millinium ago."

Thanks for the gentle correction; appreciate it.

Still: that's an awfully big hole in the ground up there.
Consider from where I lived (Susanville), it took an hour at 60 mph to ascend to where the mountain top was sheered-off by the explosion.

No matter how one slices or dices it?

Mt Lassen was one big mountain at one time.
Larger than anything we've around today on the NA continent, I'd have to think.

[Doctor Stochastic]

It's possible that the Toba event (Sumatra I think) wiped out all but a few thousand people. Yellowstone could do the same. (Assuming we don't collide with an astroid, die of anthrax, or have to watch network television first.)

[USA]

There has been a bunch of small earth quakes here in Roy area, which is very close to Mt Rainier.Ever since we had that big one that jolted us.