December 31, 2008

Yellowstone Swarm

Is the world's largest supervolcano about to erupt? An unprecedented cluster of several hundred small earthquakes has shaken the Yellowstone caldera in the last few days.

Three times in the last 2.1 million years, the Yellowstone volcano has an eruption about 1000 times larger than Mount St Helens, covering much of North America with a thick layer of ash.

As Yellowstone geologists explain,

"Precursors to volcanic eruptions include strong earthquake swarms and rapid ground deformation and typically take place days to weeks before an actual eruption."

The quakes continue and you can follow them in real time. A GPS graph measuring uplift is here.

Since 1975, when geologists discovered that Yellowstone caldera had risen 28 inches in 50 years, the caldera has been closely monitored. Since 2004 the uplift accelerated to 3 inches per year.

It has been about 640,000 years since the last major eruption. Time for another burp?

(Update: my father-in law who is a geologist says, probably not. He says the earthquakes in the current swarm are small potatoes.)

Posted by David at December 31, 2008 08:32 AM
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