Posted on 09/07/2005 10:35:31 AM PDT by LesbianThespianGymnasticMidget
BEND, Ore. (AP) -- A recent survey of a bulge that covers about 100 square miles near the South Sister indicates the area is still growing, suggesting it could be another volcano in the making or a major shift of molten rock under the center of the Cascade Range.
Recent eruptions at nearby Mount St. Helens in Washington state have rekindled interest in the annual Sisters survey and its findings.
Oregon has four of the 18 most active volcanoes in the nation -- Mount Hood, Crater Lake, Newberry and South Sister. A recent U.S. Geological Survey report said monitoring is inadequate at all of them, with only basic monitoring at about half of the active volcanoes.
Image Galleries
The Fury of Volcanoes
Mount St. Helens in 2004
Unlike the volcanoes, the bulge gets an extensive annual survey to track its growth. Spread out across an area nearly as big as the city of Portland, It's centered about three miles southwest of the South Sister, about 25 miles from Bend.
The results of the late August survey won't be ready for weeks, but scientists have reached some conclusions about the bulge from past monitoring.
They say it probably began growing in 1997 and has been rising ever since at a rate of about 1.4 inches a year. It was first observed from space using a relatively new imaging technology known as radar interferometry that can measure changes in the Earth's surface.
The likely cause of the bulge is a pool of magma that, according to Deschutes National Forest geologist Larry Chitwood, is equal in size to a lake 1 mile across and 65 feet deep.
The magma lake is rising 10 feet each year, under tremendous pressure, and it deforms the Earth's surface as it expands, causing the bulge.
Other causes could be anything from the birth of a new volcano -- a fourth Sister in the making -- to a routine and anticlimactic pooling of liquid rock, researchers say.
"The honest and shortest answer is, we don't know,'' said Dan Dzurisin, a USGS geologist.
Dzurisin recently led a three-person leveling crew on a slow walk across the top of the bulge. They were hoping to detect any change in its surface using survey equipment accurate to one-sixteenth of an inch for every mile measured.
Dzurisin's survey data, in concert with space imaging and satellite positioning measurements from two dozen fixed points on the bulge, give scientists an idea of the bulge's depth and size.
Additional information from seismographs and chemical monitoring of area springs reveal movement of the magma underground. A swarm of 350 small earthquakes in March 2004 indicated magma was on the move, but the bulge has been quiet ever since.
Whether the magma will move again or ever reach the surface is a mystery. But if it did, geological history suggests it would result only in small cinder cones that spew ash and lava.
The good news is that such an eruption likely would not seriously affect any population centers, Chitwood said.
Such cones are the most common volcanic features on Earth, he added. Central Oregon has about 600. Basalt flows have occurred in the area of the bulge every 1,000 to 1,500 years for the past 4,000 years, he said. And the area is due for another.
"The bulge is on time,'' Chitwood said. "The bus has arrived.''
We really enjoy the Hatfield Marine Science Center across the bay for this kind of thing.
click on this photo link, for a panoramic view from space of Sisters, and central Oregon:
http://130.166.124.2/panoramas/oregon/sisters_or_60k.jpg
"...forewarned *is* forearmed.",<
Uh-huh...like this is gonna change my *plans* for this weekend...
"..she better lava me now, or lava me not..."
;^D
Any harmonic tremor?
Super volcano?
I've flown over Sisters a few times. Anybody who has can tell you this is one of the dog ugliest, craggiest, moonscape terrains they've ever seen, and totally able to produce extraordinary, cataclysmic events.
But Oregon has a history of them. There are huge escarpments and lava fields in Eastern Oregon from eruptions in the 10-20 million years ago timeframe that rivaled the last time Yellowstone went.
Ah, but you'd be completely wrong about that. It's astoundingly beautiful around there.
Worse than I thought, then.
What was that you were telling me about wanting to participate in [some] "XSport"? ;^)
"Care to go rafting on a pyroclastic flow? Definitly Class VI + =0"
Lends a whole new meaning to the term, "hottie".
"click on this photo link, for a panoramic view from space of Sisters, and central Oregon:"
Interesting.
And in the distance I see a little *spit* o'land.
That's a *5* hour drive from there to there, eh?
>...forewarned *is* forearmed."
"Uh-huh...like this is gonna change my *plans* for this weekend..."
HA!!
No I didn't think it would, you'd walk on the fires of perdition for the potential prospect(s) in store for you.
This I know. {g}
Just that it segwayed [nicely] into the topic we discussed the other day via email concerning inherent risk(s) associated with living in various geographic locations.
I'm certain you're very well versed on the situation in your "backyard".
"..she better lava me now, or lava me not..."
Cute, even witty.
But should that magma start flowing?
I'll wager 1,000 quatloos you'll be paddling your kayak like *2* MFs, ---> that-a-way --->. :o)
...*fact*. ;^)
Has Washington recently changed its appearance? Does it smell better?
---
No, but it's been a long time for Oregon and it's getting desperate.
Remember the old bar line about a 4 at 10 looking like at 10 at 4?
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