Oregon Is Growing A Mystery Bulge

nedwolf writes "LiveScience is reporting that a 100 square mile bulge has been rising in Oregon. First observed from a satellite using a relatively new technology called 'radar interferometry', some believe this to be the formation of a new volcano. I think it's just happy to see me."

Comments

Baby Sister?

[ackthpt]

Looks quiet now.

To put things into perspective here's recent quakes throught the US, notice the activity in the state of California, to the south.

Back in the late 90's there were swarms of minor earthquakes around the Long Valley Caldera, the vicinity of California where Mammoth Lakes and Mammoth Mountain are located. Swarms of earth quakes, 4.0 (Richter) and lower, most lower than 2.0, were up to 600 per 24 hours for a period of about two weeks, and ground elevations were observed changing (similarly to those in Oregon) slightly, but as you can see all is quiet and nothing happened. Long Valley is the caldera of a very large, dormant volcano.

Here is a good example of a swarm of aftershocks.

This would be a shield volcano

[ReformedExCon]

A shield volcano is formed when a large pool of magma forms and pushes the land above it upwards. These types are not likely to erupt, though they will erupt violently if the magma is able to push through the surface (kind of like a giant geologic pimple). These volcanos are great for tourism because of the typically accompanying hot springs and year-round greenery.

I like Oregon a lot. I just wish it were easier to get to.

Re:This would be a shield volcano

[Anonymous Coward]

Volcano lesson for the day:
This is not a shield volcano.

A shield volcano is actually made by layers and layers of basaltic magma. Hawaii (the large, flat volcanos) are shield volcanos. Basaltic magma is very hot, iron rich, and flows easily. It tends to bubble and gurgle, not explode. There's a reason hawaiian eruptions don't produce ash clouds - no big explosion.

http://volcanoes.usgs.gov/Products/Pglossary/Shiel dVolcano.html

In Oregon, we have very few shield volcanos. Most of ours are composite volcanos (made from lava pusing up a dome, plus layers of flowing ash) and cinder cones (made from piles of ejected cinders). Our magmas are rhyolitic, meaning they contain little iron, it is at relatively cooler temperatures, and tend to explode violently (like Mount St. Helens or the famous Mount Mazama... now crater lake).

http://vulcan.wr.usgs.gov/Glossary/StratoVolcano/d escription_composite_volcano.html

Re:This would be a shield volcano

[the phantom]

1) Obsidian is generally related to rhyolitic flows. Where basalt is high in iron and magnesium (thus, mafic -- ma from magnesium, fic from ferous or feric), rhyolite is full of silicon. Andesite is sort of in between. Silicic lava is very viscous -- it tends not to flow as well, and get backed up in a volcano. Then, when enough pressure is present, is 'slodes. Obsidian is a very, very silicic rock. It cools from lava to solid rock very quickly, so does not from a crystaline structure, but it is chemically very similar to rhyolite or pumice. Thus, that does not refute the grandparent, but rather reinforces it.

2) There have been basalt flows. It is possible for composite volcanoes to have basalt flows. Think about what composite means -- a combination of two or more things. Composite volcanoes are not quite sheild volcanoes, and not quite cinder cones. Eruptions can be either highly mafic, or highly silicic. Thus, basalt flows are not out of place.

3) The sharp, dark red rock that you are seeing is probably andesite. There is a lot of andesite in the region. Andesite is a fairly silicic rock (though it does get the red color from more mafic minerals). It is another kind of rock that can be expected to come from a composite volcano.

So, while your observations don't exactly fit with the grandparent's comment, they are not inconsistant.

Re:Same fault line

[geomon]

both regions lie along the same fault line.

No. Both regions sit atop the seismically active area named "The Ring Of Fire", which is a poetic name given to a seismically active rim boundary indicated by plots of earthquake epicenter. The purple band you see on the map is the area is the subduction zone of the Pacific Plate.

This is not a fault zone. Fault zones arise in response to subduction.

Re:Mr. President, Dr. Evil is on the line...

[JabberWokky]

Add him as a foe (click on the little white sphere), go to your Preferences (link in the upper left corner), pick "Comments" and change your People Modifier setting to drop all posts by foes to -6. You'll never see his comments ever again.

--
Evan

Re:New measurement technique != new geology

[Scarblac]

They are now able to detect this swelling...how do we know it isn't normal.

We don't, of course. The bit below is from a mysterious item usually related to as "the fucking article", bolding mine:

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.

Re:Super Volcano?

[jim_v2000]

If this is indeed another one, then the fallout from Katrina is going to seem mild in comparison.

I live in Oregon, and let me tell you, if a volcano blew 25 miles from Bend, the most we'd lose is some trees and scrub brush. Even if Bend got taken out...it's only a town of about 60,000 with roads leading out in all directions. Wouldn't be a particularly bad disaster. Most of the population of Oregon lives about 150 miles west on the other side of the Cascade mountain range.

Re:Same fault line

[keraneuology]

This is not a fault zone. Fault zones arise in response to subduction.

Not always. San Andreas is a transform fault - no subduction involved. See http://jersey.uoregon.edu/~mstrick/AskGeoMan/geoQu erry22.html

Additional technical papers on the bulge

[dtmos]

At the 98th Annual Meeting of the Cordilleran Section of the Geological Society of America (May 13-15, 2002), in Corvallis, Oregon, there were several papers on this bulge in the "Hazards and Risks from Cascade Volcanoes" session. Apparently it was discovered in April 2001; the GSA even sent out a press release about the bulge in May 2002.