Volcanoes Essay -- essays research papers fc

A Look Into Vol potentiometeroes I. Introduction Volcano defined is a mickle or hill formed by the hookup of materials erupted through maven or more openings (called volcanic vents) in the earths surface. The term volcano can also refer to the vents themselves. Most volcanoes impart steep sides, besides nigh can be gently sloping mountains or even flavorless tablelands, plateaus, or plains. The volcanoes above sea level are the best known, but the vast majority of the worlds volcanoes lie beneath the sea, formed along the ball-shaped oceanic ridge systems that crisscross the deep ocean floor. According to the Smithsonian Institution, 1511 above-sea volcanoes have been active during the past 10,000 years, 539 of them erupting mavin or more times during create verbally history. On average, 50 to 60 above-sea volcanoes worldwide are active in any given year about half of these are continuations of eruptions from forward years, and the rest are new. Mount St. Helen Volcanic eruptions in populated regions are a significant threat to people, property, and agriculture. The danger is mostly from fast-moving, hot flows of volatilely erupted materials, falling ash, and high-pitchedly destructive lava flows and volcanic debris flows. In addition, explosive eruptions, even from volcanoes in unpopulated regions, can eject ash high into the atmosphere, creating drifting volcanic ash clouds that pose a serious opine to airplanes. II. Volcano Formation All volcanoes are formed by the accumulation of magma which is molten rock that forms below the earths surface. Magma can erupt through one or more volcanic vents, which can be a star opening, a cluster of openings, or a long crack, called a gent vent. It forms deep within the earth, generally within the upper part of the winding-clothes which is one of the layers of the earths crust, or less commonly, within the base of the earths crust. High temperatures and pulls are needed to form magma. The solid mantle or crustal rock essential be melted under conditions typically reached at depths of 50 to 60 mi. (80 to 100 km) below the earths surface. Once tiny droplets of magma are formed, they begin to upraise because the magma is less dense than the solid rock surrounding it. The processes that cause the magma to muster are poorly understood, but it generally moves upward toward lower pressure regions, squeezing into spaces between minerals within the soli... ...the first blobs of melt. As melting continues different minerals start to melt as well, and the chemistry of the magma changes. From studies like this geologists have immovable that the early stages of a Hawaiian volcanos life is generated by magmas derived from only fiddling degrees of partial melting (such as only 5% of the source melting and the rest staying behind). On the otherwise hand, when the volcano really gets going (such as at Kilauea and Mauna Loa), the percentage of source rock that melts to produce the magma i s perhaps as high as 20%. There are many other ways in which chemistry is used in volcanology, including the studies of volcanic gases, crater lakes, and trying to determine the temperatures that lava had at the time they were erupted even long after the eruption has ended. Bibliography Bibliography 1999 Microsoft Encarta Volcanoes 1980 USGS www.vulcan.wr.usgs.gov 2000 Volcano World http//volcano.und.nodak.edu/vwdocs/frequent-questions/grp13/question1544.html 1980-2000 USGS www.vulcan.wr.usgs.gov/photo/volcanoes/MSH/framework.html 1993-2000 Microsoft Corporation motley volcano media 2000 FEMA www.fema.gov/library/volcanof.htm Word Count 2186