Monday, April 30, 2012

New Info On Yellowstone Suggests "Super Eruption" Was Two Smaller Eruptions

Yellowstone volcano has long thought to have had a large super eruption over 2 million years ago, but new evidence is suggesting that while 2 million years ago Yellowstone DID erupt with a VEI 7 or 8 eruption, it was not as big as once thought, and was followed 6,000 years later by a smaller eruption. The result was an ash layer that appeared to be one layer but was actually two. This suggests that Yellowstone is NOT as powerful as once thought, but is more active.

The study revealed that the Island Park Caldera is actually much more active than previously thought, and the new information might assist scientists in better predicting an eruption from Yellowstone, given that the timeline has now changed. The last magmatic eruption in the Yellowstone caldera was some 70,000 years ago, and an episode of phreatic eruptions that created a 5km wide crater (now Yellowstone Lake). 

Scientists were using a new "Rock Clock" method to determine the ages of ash and rock layers within the Huckleberry Ridge, and were surprised at the data they found. The data suggests that Yellowstone's explosive eruptions were around 12 percent weaker than previously thought, but smaller eruptions are actually more numerous. The last eruptive activity of any kind in Yellowstone occurred somewhere around 1350BC (give or take around 200 years), and was limited to hydrothermal eruptions.

Knowing when, or how, Yellowstone might erupt in the future is one of volcanology's biggest challenges, given the impact an eruption from Yellowstone might have. But the new data seems to shrink the idea that Yellowstone is capable of a world-ending eruption (one thing I highly disagree with most scientists about is that any event on earth is capable of wiping out 'all life'... life did not simply get wiped out and reappear on the planet, there are always survivors). Indeed, the new data seems to suggest that Yellowstone is not capable of "blotting out the sun worldwide", but is still a very dangerous volcano to anyone within about 100KM.

This is good news for anyone who was worried that Yellowstone could be a 'world ender', and probably bad news for anyone who wants to scare people into doomsday nonsense for the tabloids. An eruption from Yellowstone today would likely be much weaker than previous eruptions, given that as far as anyone knows, no new magma has been introduced into the Yellowstone system for a very long time. Scientists theorize that the current magma chamber consists of partially cooled magma known as 'crystal mush', and any eruption would likely result from water flashing into steam when it seeps into hot rock (a phreatic eruption). These types of eruptions are short lived, and very rarely pose a threat outside of 1km, but anything is possible.

In any case, this new info will definitely be helpful to understanding further the history and potential of the Yellowstone caldera.

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