> murdoch wrote: > This includes such concerns as super volcanoes (Yellowstone is said to > have exploded every 600-800 thousand years, over the last 2 million, > with the last explosion 600,000 years ago),
Here's a few references: SUPER VOLCANO -- YELLOWSTONE PARK It is little known that lying underneath one of the United States largest and most picturesque National Parks - Yellowstone Park - is one of the largest "super volcanoes" in the world. Scientists have revealed that Yellowstone Park has been on a regular eruption cycle of 600,000 years. The last eruption was 640,000 years ago·so the next is overdue. The next eruption could be 2,500 times the size of the 1980 Mount St. Helens eruption. Volcanologists have been tracking the movement of magma under the park and have calculated that in parts of Yellowstone the ground has risen over seventy centimeters this century. The first caldera-forming eruption occurred about 2.1 million years ago. The eruptive blast removed so much magma from its subsurface storage reservoir that the ground above it collapsed into the magma chamber and left a gigantic depression in the ground- a hole larger than the state of Rhode Island. The huge crater, known as a caldera, measured as much as 80 kilometers long, 65 kilometers wide, and hundreds of meters deep, extending from outside of Yellowstone National Park into the central area of the Park. The most recent caldera-forming eruption about 650,000 years ago produced a caldera 53 x 28 miles (85x 45 kilometers) across in what is now Yellowstone National Park (Figure 2). During that eruption, ground-hugging flows of hot volcanic ash, pumice, and gases swept across an area of more than 3,000 square miles. Image of area covered by previous eruptions over the western US. http://www.solcomhouse.com/yellowstone.htm Yellowstone Volcano Observatory (YVO) http://volcanoes.usgs.gov/yvo/ YVO FAQs http://volcanoes.usgs.gov/yvo/faqs.html Q. How large were the giant eruptions in the Yellowstone National Park region in comparison to other large historic eruptions? A. Figure 2 shows that the three largest Yellowstone eruptions emitted much more material than the eruptions of Mount St. Helens (1980), Mount Pinatubo (1991), Krakatau (1883), Mount Mazama (7,600 years ago), and Tambora (1815). http://volcanoes.usgs.gov/yvo/figures/fig2.html VOLCANOES -- More than 500 volcanoes are known to have erupted on the earthâs surface since historic times, and many more have erupted on the ocean floor unobserved by humans. Fifty volcanoes have erupted in the United States, which ranks third, behind Indonesia and Japan, in the number of historically active volcanoes. Image of Volcanoes Around The World. Some emit steam and searing-hot noxious gases, some eject choking and blinding, sunlight-blocking ash; others liquid rock called lava. Many exhibit a combination of these. Volcanic eruptions are thought to be responsible for the global cooling that has been observed for a few years after a major eruption. The amount and global extent of the cooling depend on the force of the eruption and, possibly, its latitude. When large masses of gases from the eruption reach the stratosphere, they can produce a large, widespread cooling effect. http://www.solcomhouse.com/volcano.htm ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ------------------------ Yahoo! Groups Sponsor ---------------------~--> Buy Ink Cartridges or Refill Kits for Your HP, Epson, Canon or Lexmark Printer at Myinks.com. Free s/h on orders $50 or more to the US & Canada. http://www.c1tracking.com/l.asp?cid=5511 http://us.click.yahoo.com/l.m7sD/LIdGAA/qnsNAA/FGYolB/TM ---------------------------------------------------------------------~-> Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
