Sunday, March 20, 2011

Super volcano eruptions

In the past, several super vulcano eruptions sufficiently large to cause a global disaster have occurred, on average, every 100,000 years.Most volcanoes that produce super-eruptions are very long-lived (active over millions of years), produce very large explosive eruptions, and remain dormant for long periods (from thousands to hundreds of thousands of years) between major eruptions.The appearance of the volcano itself after eruption is also distinctive: it doesn’t conform to the common image of a volcano as a lofty, symmetrical, conical structure.The power of a volcano is measured by how much magma and ash it produces. A supervolcano is the biggest, most destructive volcano.Supereruptions require a very large volume of magma with strong explosive potential. Explosive potential results from a high content of volatile constituents (mostly H2O) that can form gas bubbles, combined with high viscosity to inhibit escape of the bubbles from the magma; it is the bursting of these trapped bubbles that drives an explosion. Supereruptions are “the ultimate geologic hazard,” in terms of the immediate and devastating impact of eruption products on our social infrastructure, and with regard to the longer-term climatic effects that will arise from loading the stratosphere with sulfur-rich gases.A supervolcano eruption packs the devastating force of a small asteroid colliding with the earth and occurs 10 times more often—making such an explosion one of the most dramatic natural catastrophes humanity should expect to undergo.Yellowstone is the largest super volcano on Earth!Beneath the beauty of America’s first national park is a killer volcano that is 1,000 times more powerful than Mt. Saint Helens and hundreds of times more powerful than all the volcanos in Iceland …combined!

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