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Volcano Facts Fun stuff! Range of ashfall for volcanoes Mt. St. Helens Where did the term "volcano" come from? The word "volcano" comes from the little island of Vulcano in the Mediterranean Sea off Sicily. Centuries ago, the people living in this area believed that Vulcano was the chimney of the forge of Vulcan -- the blacksmith of the Roman gods. Where did the term "volcano" come from? ... They thought that the hot lava fragments and clouds of dust erupting from Vulcano came from Vulcan's forge as he beat out thunderbolts for Jupiter, king of the gods, and weapons for Mars, the god of war. How many active volcanoes are there in the world? About 500 active volcanoes are known on Earth, not counting those that lie beneath the sea. What are some positive products from volcanoes? The Earth's crust, on which we live and depend, is in large part the product of millions of once-active volcanoes and tremendous volumes of magma that did not erupt but instead cooled below the surface. Volcanic ash can increase soil fertility More positives ... Heated groundwater can be tapped for geothermal energy Heated groundwater has concentrated valuable minerals, including copper, tin, gold, and silver, into deposits that are mined throughout the world What was the largest volcanic eruption in the 20th century? 1912 at Novarupta on the Alaska Peninsula. An estimated 15 cubic kilometers of magma was explosively erupted during 60 hours beginning on June 6 -- (which is equivalent to 230 years of eruption at Kilauea (Hawaii) or, about 30 times the volume erupted by Mount St. Helens (Washington) in 1980.) Where is the largest active volcano in the world? Mauna Loa (Hawaii) is the world's largest active volcano, projecting 13,677 feet above sea level, its top being over 28,000 feet above the deep ocean floor. From its base below sea level to its summit, Mauna Loa is taller than Mount Everest. Cascade Range Which Cascade Range volcano erupted through a glacier? Mount Garibaldi (British Columbia, Canada) is a composite cone and domes built on a glacier. It is one of the larger volcanoes (6.5 cubic kilometers) in a chain of small Quaternary volcanic piles -- the Garibaldi Belt -- within the southern Coast Mountains of British Columbia. How dangerous is Mount Rainier? Although Mount Rainier (Washington) has not produced a significant eruption in the past 500 years, it is potentially the most dangerous volcano in the Cascade Range because of its great height, frequent earthquakes, active hydrothermal system, and extensive glacier mantle. Mount Rainier has 26 glaciers containing more than five times as much snow and ice as all the other Cascade volcanoes combined. How would an eruption of Mount Rainier compare to the 1980 eruption of Mount St. Helens? Eruptions of Mount Rainier usually produce much less volcanic ash than do eruptions at Mount St. Helens. However, eruptiontriggered debris flows at Mount Rainier are likely to be much larger -- and will travel a greater distance -- than those at Mount St. Helens in 1980. Furthermore, areas at risk from debris flows from Mount Rainier are more densely populated than similar areas around Mount St. Helens. How much ash was there from the May 18, 1980 eruption of Mount St. Helens? During the 9 hours of vigorous eruptive activity, about 540 million tons of ash fell over an area of more than 22,000 square miles. The total volume of the ash before its compaction by rainfall was about 0.3 cubic mile, equivalent to an area the size of a football field piled about 150 miles high with fluffy ash. How often do Alaskan volcanoes erupt? Alaskan volcanoes have produced one or two eruptions per year since 1900. At least 20 catastrophic caldera-forming eruptions have occurred in the past 10,000 years The awesome eruption of 1912 at Novarupta in the Katmai National Monument is the most recent. Scientists are particularly concerned about the volcanoes whose eruptions can affect the Cook Inlet region, where 60 percent of Alaska's population lives.