Showing posts with label eruption. Show all posts
Showing posts with label eruption. Show all posts

Friday, January 02, 2009

Yellowstone: eq swarm continues. A precursor?

This reporter at US News & World Report has posted five articles exploring the quicksand data under the boiling cauldron that is the equation of eq swarm/eruption. Bad puns to be sure, but the data is both solid and quicksand because though USGS and Utah Univ collect a lot of data, they have no context for understanding if all this activity is a precursor or not. And there the issue boils, as many thousands of people across the globe attempt to understand what has happening this past week at Yellowstone and what it may mean for the future of mankind.

As an indicator of worldwide interest, my blog normally gets 100 hits a day. When I posted about Obama being our "First Non-Christian President" on Nov 22, I got 1000 hits. But these past two days the hits have blown the charts away.

With these successive posts by the US News reporter, it seems that there is a dividing line between the public go-to guy, Dr. Jacob Lowenstern, and other scientists. That divergence becomes obvious with this latest update from the US NEws reporter. In other words, it seems like the reporter just ain't buying the "nothing to see here" routine from Dr. Lowenstern any more:

Yellowstone Earthquakes: Supervolcano Update
January 02, 2009 03:31 PM ET
BY James Pethokoukis

A Yellowstone earthquake update:

1) The rumbling continues, including 3.5, 3.0 and 3.2 quakes just today2) Here is some more Jake Lowenstern (the Yellowstone volcano scientist) analysis (via TIME):

Jake Lowenstern, Ph.D.,YVO's chief scientist, who also is part of the USGS Volcano Hazards Team, told TIME that it doesn't appear a supervolcano event is imminent. "We don't think the amount of magma exists that would create one of these large eruptions of the past," he said. "It is still possible to have a volcanic eruption comparable to other volcanoes. But we would expect to see more and larger quakes, deformation and precursory explosions out of the lake. We don't believe that anything strange is happening right now." Last summer, YVO installed new instrumentation in boreholes 500 to 600 feet deep to better detect ground deformation. Says Lowenstern: "We have a lot more ability to look at all the data now.

3) Here is a passage on the Yellowstone supervolcano from "A Short History of Nearly Everything" by Bill Bryson. He interviews a Yellowstone geologist, Paul Doss. I don't find it reassuring:

I asked him what caused Yellowstone to blow when it did.

"Don't know. Nobody knows. Volcanoes are strange things. We really don't understand them at all. Vesuvius, in Italy, was active for three hundred years until an eruption in 1944 and then it just stopped. It's been silent ever since. Some volcanologists think that it is recharging in a big way, which is a little worrying because two million people live on or around it. But nobody knows."

"And how much warning would you get if Yellowstone was going to go?"
He shrugged. "Nobody was around the last time it blew, so nobody knows what the warning signs are. Probably you would have swarms of earthquakes and some surface uplift and possibly some changes in the patterns of behavior of the geysers and steam vents, but nobody really knows."

"So it could just blow without warning?"

He nodded thoughtfully. The trouble, he explained, is that nearly all the things that would constitute warning signs already exist in some measure at Yellowstone. "Earthquakes are generally a precursor of volcanic eruptions, but the park already has lots of earthquakes-1,260 of them last year. Most of them are too small to be felt, but they are earthquakes nonetheless."

A change in the pattern of geyser eruptions might also be taken as a clue, he said, but these too vary unpredictably. Once the most famous geyser in the park was Excelsior Geyser. It used to erupt regularly and spectacularly to heights of three hundred feet, but in 1888 it just stopped. Then in 1985 it erupted again, though only to a height of eighty feet. Steamboat Geyser is the biggest geyser in the world when it blows, shooting water four hundred feet into the air, but the intervals between its eruptions have ranged from as little as four days to almost fifty years. "If it blew today and again next week, that wouldn't tell us anything at all about what it might do the following week or the week after or twenty years from now," Doss says. "The whole park is so volatile that it's essentially impossible to draw conclusions from almost anything that happens."

Evacuating Yellowstone would never be easy. The park gets some three million visitors a year, mostly in the three peak months of summer. The park's roads are comparatively few and they are kept intentionally narrow, partly to slow traffic, partly to preserve an air of picturesqueness, and partly because of topographical constraints. At the height of summer, it can easily take half a day to cross the park and hours to get anywhere within it. "Whenever people see animals, they just stop, wherever they are," Doss says. "We get bear jams. We get bison jams. We get wolf jams."

In the autumn of 2000, representatives from the U.S. Geological Survey and National Park Service, along with some academics, met and formed something called the Yellowstone Volcanic Observatory. Four such bodies were in existence already-in Hawaii, California, Alaska, and Washington-but oddly none in the largest volcanic zone in the world. The YVO is not actually a thing, but more an idea-an agreement to coordinate efforts at studying and analyzing the park's diverse geology. One of their first tasks, Doss told me, was to draw up an "earthquake and volcano hazards plan"-a plan of action in the event of a crisis.

"There isn't one already?" I said.
"No. Afraid not. But there will be soon."
"Isn't that just a little tardy?"
He smiled. "Well, let's just say that it's not any too soon."

Thursday, January 01, 2009

More on Yellowstone, harmonic tremors

from Scientific American

"Any disaster fiend will tell you that Yellowstone National Park is long overdue for a monster eruption that could leave as much as half the U.S. under a blanket of ash. And there are rumblings the big one could be imminent in the wake of a series of 30-plus mini-earthquakes in the park over the past few days—too weak to be felt by humans for the most part but picked up by the seismometers at the University of Utah."

"After all, the geologic record shows that the giant caldera we affectionately call Yellowstone has blown every 600,000 years or so over the past 2 million years. The last big eruption? About 640,000 years ago when the park spit out about 240 cubic miles worth of rock, dirt, magma and other stuff."

Small earthquake swarms are not indicators of imminent volcanic eruptions, but harmonic tremors are. From USGS visual glossary:

harmonic tremor: Harmonic tremor describes continuous rhythmic earthquakes that can be detected by seismographs. Harmonic tremors often precede or accompany volcanic eruptions. The visual glossary has an example to look at, all the better to compare the harmonic tremors as seen on the University of Utah's seismos, which I posted earlier. Decide for yourself if they are ground quakes or magma tremors.

But here's from Rightpundits:
It should be noted that all the earthquakes have been intense and concentrated in one area, which happens to be above the magma chamber. [ see .gif below ] The scariest part of this story is the “harmonic tremors” that scientists have picked up. They are a low level constant rumbling, which usually indicates magma movement.
Continuing the Scientific American excerpt:

"In recent years, Yellowstone's caldera has been rising thanks to uplifting magma beneath it—leading to more cracks, hot springs and even more frequent eruptions of Steamboat Geysers. Paired with the earthquakes, such magma movement might presage an eruption—either big or small. Unfortunately, scientists can't really predict when the next such eruption will happen, and the range of possibilities is large: from later today to a million years from now."

"How will we know if we should start worrying? The real warning signs will be rapid changes in the shape of the ground as well as volcanic gases leaking from the ground, neither of which have been sighted—yet."

If indeed the supervolcano is getting ready to blow, it does not necessarily have to be a supereruption. It could be a small one or it could by a hydrothermic event. Time will tell. Meanwhile, the unusual swarm continues. And is should be noted that a day and a half ago the USGS started pulling the eq's from their list and have not posted all of them that have occurred, according to other sites that have different seismographs and are noting more activity than USGS is publicly posting.

MAP 2.7 2009/01/01 12:51:24 44.548 -110.361 0.2 (38 mi) ESE of West Yellowstone, MT
MAP 2.4 2009/01/01 10:13:52 44.541 -110.389 0.2 (36 mi) ESE of West Yellowstone, MT
MAP 2.4 2009/01/01 10:12:57 44.325 -110.388 37.0 (42 mi) ESE of West Yellowstone, MT
MAP 2.3 2009/01/01 10:06:51 44.529 -110.370 0.5 (37 mi) ESE of West Yellowstone, MT
MAP 2.3 2009/01/01 10:02:57 44.528 -110.346 0.2 (39 mi) ESE of West Yellowstone, MT
MAP 1.6 2009/01/01 06:59:39 44.504 -110.340 0.9 (39 mi) ESE of West Yellowstone, MT
MAP 2.1 2009/01/01 05:29:09 44.507 -110.309 1.5 (40 mi) SSW of Cooke City-Silver Gate, MT
MAP 2.2 2009/01/01 05:19:51 44.509 -110.350 1.7 (39 mi) ESE of West Yellowstone, MT