Three Alaskan Volcanoes Rumbling To Life - Reuters

[hatrack]

From the "Jesus Christ, now what?!?!" Department . ..

ANCHORAGE - Anchorage residents could see a cloud of steam over the weekend from a volcano 900 miles (1,500 km) away -- one of three Alaska volcanoes showing signs of unrest.

The three volcanoes, including two located on remote Aleutian islands distant from any population centers, are setting off frequent tremors and minor bursts of ash or steam, seismologists said on Tuesday.
Cleveland Volcano, 900 miles (1,500 km) southwest of Anchorage, had a small eruption on Friday, said the Alaska Volcano Observatory, which monitors Alaska's more than 40 active volcanoes.

Its ash plume rose to a height of nearly 15,000 feet (4.6 km) above sea level, observatory scientists said. A cloud of steam from the 5,676-foot (1,730-m) volcano's peak was visible from Anchorage over the weekend.

EDIT

The other volcanoes showing unrest are 5,925-foot (1,800-m) Tanaga Volcano and 11,070-foot (3,400-m) Mount Spurr, 75 miles (120 km) west of Anchorage.

EDIT

http://www.planetark.com/dailynewsstory.cfm/newsid/32932/story.htm

[whatever4]

1. oh

sonofabitch. I popped back on, wasn't even going do anything but read the rest of the day. Swear. Three of them. Not one, not two. This just can't be good. Not that I know, I mean I lived up north there for a while. Even saw an island, and brought home some rough jade, it being the thing to do, pretty green rocks. Dang. Three of them? Hope this isn't much of anything.

[phantom power]

2. A buddy of mine reminded me of something yesterday.

He was talking about geological unrest caused by the melting of the last glaciers. When ice piles up into mile-high glaciers, it puts a lot of weight on a continent. If all that ice disappears, the weight is shifted. It can trigger fault-lines, maybe goose up a volcanoe.

I don't know if we've seen ice melting on the kind of scale required, but we do know that glaciers are disappearing. It just makes me wonder.

Maybe we're just entering a cycle of high earthquake/volcano activity.

[electropop]

3. Or the Rapture Right have accomplished their mission...

...and it's the End of Days. :scared:

[Dogmudgeon]

10. I think it's called "Isostasy"

"Triggering" faults has always been a topic of controversy in geological circles, so the theory is about to get some serious testing. The whole Pacific Ring of Fire has been more active in the last year. Granted, it's not about to blow a hole in the Earth, but it's a significant change. The isostasy (sometimes it's also called isostasis) that happened 18 kYA - 12 kYA resulted in a lot of geographic changes aside from the disappearance of the ice sheets and the increase of sea levels.

We should also expect more seismic activity around Antarctica. While the ice is melting at the "edges" of that continent, the center is, for some reason, piling up ice. (I think it's because of stronger atmospheric convection bringing more water vapor and, ergo, snow to the pole.) That will only happen in the Arctic when something happens to destabilize the air inversion over the pole -- something like the loss of the many "minor" thermohaline currents that regulate temperature in Europe and the "hyperborean" lower Arctic.

Of course, when the Arctic inversion collapses, we'll probably be much too busy worrying about blizzards and floods to give much notice to earthquakes.

--p!

[ayeshahaqqiqa]

4. Are these volcanoes on a major fault line?

My geography is a bit shaky here, as I don't know how far north the San Andreas fault goes.

[phantom power]

6. just to look at them, I'd guess the aleutians are a "hot-spot" chain

Not on a fault line, but a chain of islands left behind as the continent drifts over a magma hot-spot. Like the Hawaiian chain.

just a guess.

[progressive_realist]

11. The Aleutians are a subduction-zone island chain.

They were/are produced by the edge of the Pacific oceanic plate sliding beneath the North American continental plate.

Subduction zones are where most of the world's volcanoes and earthquakes are found. The Pacific Rim is lined with them, thus the nickname "Ring of Fire." Japan, Indonesia, and the Philippines are also subduction-zone island chains.

Subduction zones carry the potential for much stronger earthquakes than slip-slide faults like the San Andreas. There is no chance (unless geologists have discovered something new that I am not aware of) of a magnitude 9.0 earthquake like the one that triggered last year's Indian Ocean tsunami occurring along the San Andreas. The faults in California are dangerous because of the combination of frequent earthquake activity and high population densities.

By comparison, my state (Washington) does not experience many earthquakes, but we do run the risk of a mega-quake, since the remnants of the Juan de Fuca oceanic plate are still being subducted just off our coast. Geologists estimate that we have one mega-quake every few centuries, with the last one occurring in 1700. The Aleutians are geologically similar in this respect, and carry great potential for large earthquakes, including tsunami-causing mega-quakes.

For reference, the San Andreas fault system ends off the coast roughly west of Eureka, CA. There it meets with the crustal fractures at the southern edge of the Juan de Fuca plate.

So, the short answer is yes, the Aleutians are atop a dangerous fault zone. But activity in this zone is common, and probably not a cause for concern. Even a mega-quake generating a tsunami would not cause much loss of life, since the Pacific has had a tsunami-warning system in place for decades.

(All of this is from memory from a geology class taken some time ago. My information may not be completely up-to-date.)

[ChairmanAgnostic]

5. no surprise.

take a globe. no, not a flat earth version, but the real thing.
thing of the molten core of the earth as a dense incredibly heavy liquid. It also happens to be rotating.

Ok visualise it this way. Sit in a full tub. Release gas. See how the bubbles form, then waves leave that spot, only to return? OK stinky example.

Well, if you had a wave propogating motion, such as a plate shifting, it sends huge energy waves, not only up into mountains and oceans, but down into the molten core.

These waves move around a tad, and are swung a bit by the magma's rotation, but they tend to refocus in a general direction, somewhat opposite of the original plate shifting, because of the spherical shape of the earth's interior.

When so much diffuse energy hits a soft spot, any weakened plate situations, or a dormant volcano, tend to become disrupted and move and shake. also, the tectonic movements may also cause a chain reaction to plates much further away. If you consider how much energy is generated from an earthquake, and consider that a lot of that energy is distributed through a dense liquid, it is not surprising that other places react some days later.

so, if you look historically, after a HUGE earthquake in one spot, several days later, there is something happening on the other side of the globe. and because the core rotates, is never precisely opposite.

[astonamous]

7. That sounds like science... I like the bathtub example. LOL!

It all seems to make a lot of sense of the patterns. I think there were some stories about increased ground shaking in the Idaho area a couple of weeks ago and I know that they are really monitoring the Yellowstone area for increased volcanic activity the last few years.

An interesting website would be one that combines the earthquake activity along with the volcanic activity and anything else they could add like water temps. It would be fun to just watch the world as a living planet on a real-time scale.

[ChairmanAgnostic]

9. no kidding. that would be way cooool.

I wonder why no one has bothered.

[LonelyLRLiberal]

8. Looks like part of the "Ring of Fire"

This is a ring of volcanoes circling the Pacific Ocean.

See:

http://www.crystalinks.com/rof.html

[hatrack]

12. Very much so - my brother well remembers Mt. Spurr's last eruption

About 15 years back. He ended up with about 1/4" of ash on his car. The stuff was everywhere.