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Mount St. Helens Alert Status Increased
DarkHand writes "Mount St. Helens has become even more unstable in the last few hours. The U.S. Geological Surveys Cascades Volcano Observatory has increased the volcanic alert around the volcano to level 2 and released a press release: 'Over night, seismic activity at Mount St. Helens has accelerated significantly, which increases our level of concern that current unrest could culminate in an eruption. We are increasing the alert level to the second of three levels [...]. Earthquakes are occurring at about four per minute. The largest events are approaching Magnitude 2.5 and they are becoming more frequent. All are still at shallow levels in and below the lava dome that grew in the crater between 1980 and 1986. This suggests that the ongoing intense earthquake activity has weakened the dome, increasing the likelihood of explosions or perhaps the extrusion of lava from the dome.' The most recent readings at the SEP seismograph stationed on the lava dome itself are totally saturated. The ground is now literally constantly rumbling."
USGS earthquake info for Mt St Helens National Volcanic Monument area (wide view)
USGS Cascades Volcano Observatory Mt St Helens seismic observations
Pacific Northwest Seismograph Network Mt St Helens home page (earthquake list)
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FYI much of Africa has, for several weeks now, been suffering from a extraordinary plague of locusts.
n _correspondent/3689808.stm
e.g. http://news.bbc.co.uk/1/hi/programmes/from_our_ow
Hmm. I was hoping to see a live volcano eruption here, but it seems
not to be broadcasting now. Anyone knows why/what's happening ?
ifd you live in tacoma, mt. rainier is the one you worry about
pdf map of lava flow hazard from mt. rainier to tacoma
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Seismologists are expecting anywhere from nothing at all (not uncommon following an earthquake swarm, happens at Kilaeua from time to time), to a moderate event.
By comparison, the 1980 blast was a catastrophic event. A medium strength earthquake caused the entire north face of the mountain to crumble in a massive rockslide, which also uncorked the pressure on the magma underneath, resulting in a huge lateral explosion through the rock slide. Imagine a wall of rocks coming at you at 300mph. It's doubtful that something like that will happen again in our lifetimes.
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OK, I haven't done any geology in over two decades, so take this with a grain salt, but my understanding is that one of the reasons that the "big one" was so big was that St. Helens had not erupted for centuries and the top of the lava tube was blocked like a giant zit. When enough pressure finally built up to blow the cap off, it threw crap everywhere. That would indicate that the currently forecasted eruption is unlikely to be as large, although it could still be a significant event.
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Subduction zones (like those off the west coast of America) and volcanoes (such as St. Helens) are a big part of the long-term carbon cycle of the planet. Left to its own, life and chemical processes on this planet would convert all the atmospheric carbon into calcium carbonate that would be trapped in rock on the bottom of the ocean. Subduction zones and volcanoes reprocess this rock into CO2.
Once the Earth's crust cools enough, it will lock up and stop the cycle and CO2 will inexorable drop in concentration. I can't remember when this is predicted to happen, but I believe it is scheduled to occur before the Sun becomes a red giant. Of course, I'm sure our descendants (assuming we have them) will invent their own C02 extract factories to keep the Earth nicely carbonated when the time comes.
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They had some comments on the local news this morning about its severity. (I live in Vancouver - just a short drive from St. Helens.) It looks like the only thing they're predicting is a very small eruption, possible steam escapes. Nothing at all like the last one.
The only problem they expect is the possibility of dispruping flights at PDX or some of the local airports.
Contrary to the last eruption, when 57 people died, no one lives up around the volcano anymore. So, it's not like anything nearly as severe is likely.
So, even though activity is through the roof, they don't expect more than a small eruption. Even last time, here in Vancouver, we didn't get much activity at all. All the ash, darkness and horrid weather was thrown to the east of the Cascades, near Yakima and Central Washington. The rivers were flooded and clogged with debris, but other than the immediate vicinity, no one was hurt.
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Seach runs chartered volcano tours and has amassed quite a collection of pics which are up on the site too.
Anyone who has had more than 2 semesters of studying these things, feel free to correct me.
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The pressure didn't "blow the cap off" so to speak, but more precisely, the pressure caused the north face of the mountain to bulge, which became unstable and failed catastrophicaly. This released the pressure, allowing the trapped gases to forcibly eject volcanic matter both laterally and vertically, giving us the devastation of the Toutle River valley and choking the Cowlitz and Columbia Rivers, and the memorable ash cloud rising some eighteen miles into the sky.
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I actually rather like the new and improved version of St. Helens. Perfect geometry is boring. I highly recommend, once the mountain settles down, the long hike up to the rim of the crater. You come to it with a suddeness I can't describe, after hours of trudging through snow fields. All of a sudden you see the terrible beauty that destruction can bring, with, on a clear day, Mount Rainier and Mount Adams looking impossibly close by.
Even if there are no volcanoes in your backyard, mountains are great, symmetrical or smashed. Go visit some.
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I was there last summer, 23 years since the 1980 eruption, and the power with which that thing erupted is still evident all over the area.
For instance:
- A picture from high on the flank of the mountain looking back down one of the lava flows from the 1980 eruption. Notice the green patch on the hill to the left, which was missed by the lava flow.
- Looking at the same spot, this time from below. You can really see the effects of that hill here -- it diverted the lava, and everything behind it is green, while everything else was destroyed.
- A panorama from the rim of the mountain, looking down into the crater. This should give you an idea of how big a crater the eruption left. The top of the mountain was simply blown away. Even while we were there, every few minutes we could here rock tumbling down into the crater, some of them huge boulders. The sides of the caldera still aren't stable, 23 years after the fact.
- Spirit Lake. All that gray stuff you see are trees. Thousands of them. They were all killed in 1980 eruption, and are now just floating on the lake. It's called the "floating forest" of Spirit Lake.
- This is a hillside about TEN MILES from the blast site. See how the trees were just blown right over? And no, this one isn't a clearcut. According to this page, most of the trees within a 600 square kilometer area were blown over by the blast.
Another testament to the destructive power of a volcano is Crater Lake in Oregon (formerly Mt. Mazama), which blew its top 7500 years ago. The eruption, which is estimated to have been more than 40 times more powerful than Mt. St. Helens (link here) left a crater 5 miles wide, which has since filled up with water. There is still a desert-like pumice plain just north of Crater Lake, noticeable 7,500 years after the fact. Even Yellowstone National Park is itself a former volcano. It's just hard to tell when you're there because the caldera is absolutely enormous (a good portion of the park is itself within the caldera rim), and it happened 600,000 years or so ago. Just google for 'yellowstone eruption'.You can get much more information about Yellowstone's volcanos from the Yellowstone Volcanoe Observatory website.
Q.