Thursday, April 23, 2009

Yellowstone could produce a super-eruption, even soon ("How the Earth Was Made" on History Channel)


History Channel’s episode “Yellowstone” of “How the Earth Was Made” presents one of the most geologically active places on Earth, 8000 feet in elevation, on a mountain plateau nestled in the Rockies, behind the Continental Divide. It has the world’s greatest concentration of hot water springs, mudholes and geyers (“Old Faithful”). The link for the show is here.

It is the geology that is unusual and dangerous. A geologist examines the activity underneath Yellowstone Lake, and shows that the gasses have the same composition as that from a volcano – which will turn out to be a supervolcano, so massive that the caldera is not easily seen at one location. Clues were first found about 60 miles away, in obsidian and other layers in rock cliffs. More investigation shows ash from a “supervolcano” eruption 640000 years ago all over the west.

There is a colossal volcanic pipe, going down to a depth of 400 miles into the earth (more than 10% the distance to the center) that feeds the large magma chamber, which is itself about 1800 square miles. This sounds like something out of Jules Verne (“Journey to the Center of the Earth”) or even “Core”. Investigation shows that there have been other supereruptions all the way to the Snake River Plane in Idaho.

The earthquakes in this region trace out a V-shape, surrounding the huge pipe below. The movement of the North American Plate puts new land over the volcanic pipe. The eruptions (and possibly super-eruptions up to 8000 times the energy of St. Helens) occur every 600000 years at intervals of about 100 miles. The warning signs would be an increase in earthquakes. There are typically 12 small quakes a day. But in early 2009 the quakes increased by a factor of four. Furthermore the ground is rising right now in 2009. The waters in Yellowstone Lake have lifted a sunken wrecked boat showing that the land underneath the lake is rising because of the expansion of the magma chamber. The largest uplift is near the lake at about 3 inches a year.

There are other hot spots, like around Hawaii, but Yellowstone is the only one in the middle of a continent.

The film simulates a super-eruption. It could happen tomorrow. Could it have been predicted by the Maya with the 2012 date for an apocalypse? Or will it even be a super-eruption this time?

In 2005 the Discovery Channel broadcast the film "Supervolcano" (2005, BBC/Discovery Channel, dir. Tony Mitchell, with Tom Brokaw), with a fictitious massive eruption.

I visited Yellowstone in May, 1981. The picture here of “Grand Prismatic Spring” was taken by the National Park Service and is in public domain, on Wikipedia. The Wikimedia attribution page is this.

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