Wednesday, December 31, 2008

Yellowstone Earthquake Swarm Update


Illustration of a Yellowstone eruption from the Discovery Channel/BBC co-production 'Supervolcano'.

The small earthquakes are continuing today in the caldera at Yellowstone National Park, with a couple of mid-sized events near and above 3:

Recent Quake List 

Yellowstone Quake Map

It is clear that no one is sure what, if any larger significance these events will have, in terms of a volcanic or hydrothermal event, but geophysicists and geologists are keeping close watch.  FEMA has announced that it is monitoring the events.  Why?  Well, it is possible that the tremors are a precursor to an eruption, though the odds are low, as such events occur only every 600,000 years, or so.  Still, it has been approximately 640,000 years since the last supervolcano eruption at Yellowstone, and even events that happen only rarely all happen at a precise moment in time. 

Another possibility, and one more likely, it appears, is for a hydrothermal explosion.  This occurs much more frequently and can vary widely in size.  A hydrothermal explosion occurs when superheated water finds it's way to the surface and the reduced pressure creates an explosive release.  There are ten of these craters at Yellowstone, and they vary widely in size.  Debris can be thrown hundreds of feet to tens of miles in such explosions.  It is interesting to note that the cluster of small quakes now underway in Yellowstone are all in an area at the Northern end of Yellowstone Lake, the same area where most of the hydrothermal explosions in the Park have occurred over time (look for the stars in this map):

Yellowstone Volcanic Events Map

Streaming video of Old Faithful: Old Faithful Webcam Streaming Live

So, just what kind of event is about to happen, if any?  Most people's gut reaction is probably right - that is, to have a passing thought about cataclysm, think twice about going for a snowmobile run around Yellowstone Lake, and go on with a regular day.  Without 'showing your work' as math teachers like to say, this thought process reflects complex math and risk assessment.  That is, it gives weight to each of the several possibilities approximately according to their likely occurrence. 

The story has begun to get press- after four days - worldwide, but still the only comments from Dr. Smith for the record are from Monday morning, and tell us that this is unusual and we don't know what it may indicate.

If you're interested in the seismograph images for the area: University of Utah Seismograph Webcorders

If you're interested in a visual interpretation of the quake swarm check out:  Yellowstone Earthquake Swarm December 2008

If you'd like to investigate the dome-building activity go here: Yellowstone ground deformation data

Additional links:

Volcanic Locations near Yellowstone Lake

US News Article with discussion of supervolcano intensity scale

Google Blog Search for Yellowstone Quake Swarm

Google News Search

Geologic History of Yellowstone and Direction of North American Plate Movement


Seven Star Hand said...

Hi Mike,

Want a truly disturbing insight? Read what I posted before the quakes started. I know it's not your standard fare, but I did post this before these events, and it's not the first time. This is an unequivocal warning.

Here is Wisdom...

Michael Burt said...

Though I myself seem only to be capable of seeing prophesy in retrospect, it is always interesting to read what people think about the cosmological meanings of evets. Thanks for the comment. MB

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