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Location: Washington Latitude: 46.20 N Longitude: 122.18 W Height: 2,549 Meters (8,364 feet (9,677 feet before May 18, 1980))

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Volcanoes - PowerPoint PPT Presentation


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In 1943 a cinder cone started growing on a farm near the village of Paricutin in Mexico. ... The eruptive activity of Paricutin Volcano in 1947 demonstrated a

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PowerPoint Slideshow about 'Volcanoes' - Sharon_Dale


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On August 24, A.D.79, Vesuvius Volcano suddenly explosed and destroyed the Roman cities of Pompeii and Herculaneum. Although Vesuvius had shown stirrings of life when a succession of earthquakes in A.D.63 caused some damage, it had been literally quiet for hundreds of years and was considered "extinct". Its surface and crater were green and covered with vegetation, so the eruption was totally unexpected. Yet in a few hours, hot volcanic ash and dust buried the two cities so thoroughly that their ruins were not uncovered for nearly 1,700 years, when the discovery of an outer wall in 1748 started a period of modern archeology. Vesuvius has continued its activity intermittently ever since A.D.79 with numerous minor eruptions and several major eruptions occurring in 1631, 1794, 1872, 1906, and in 1944 in the midst of the Italian campaign of World War II. ...

  • In a "Vesuvian" eruption, as typified by the eruption of Mount Vesuvius in A.D.79, great quantities of ash-laden gas are violently discharged to form a cauliflower-shaped cloud high above the volcano.
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Mount Etna, towering above Catania, Sicily\'s second largest city, has one of the world\'s longest documented records of historical volcanism. Historical lava flows cover much of the surface of this massive basaltic stratovolcano, Italy\'s highest and most voluminous volcano. The Mongibello stratovolcano, truncated by several small calderas, was constructed during the late Pleistocene and Holocene over an older shield volcano. The most prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 kilometer horseshoe-shaped caldera open to the east. Two styles of eruptive activity typically occur at Etna. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more of the three prominent summit craters, the Central Crater, NE Crater, and SE Crater (the latter formed in 1978). Flank vents, typically with higher effusion rates, produce eruptions from fissures that open progressively downward from near the summit (usually accompanied by strombolian eruptions at the upper end). Cinder cones are commonly constructed over the vents of lower flank lava flows. Lava flows extend to the foot of the volcano on all sides and have reached the sea over a broad area on the SE flank.

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Global cooling often has been linked with major volcanic eruptions. The year 1816 often has been referred to as "the year without a summer". It was a time of significant weather-related disruptions in New England and in Western Europe with killing summer frosts in the United States and Canada. These strange phenomena were attributed to a major eruption of the Tambora volcano in 1815 in Indonesia. The volcano threw sulfur dioxide gas into the stratosphere, and the aerosol layer that formed led to brilliant sunsets seen around the world for several years.

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The conical form of Fuji-san, Japan\'s highest (summit elev. 3,776 meters) and most noted volcano, belies its complex origin. The modern postglacial stratovolcano is constructed above a group of overlapping volcanoes, remnants of which form irregularities on Fuji\'s profile. Growth of the Younger Fuji volcano began with a period of voluminous lava flows from 11,000 to 8,000 years before present (BP), accounting for four-fifths of the volume of the Younger Fuji volcano. Minor explosive eruptions dominated activity from 8,000 to 4,500 BP, with another period of major lava flows occurring from 4,500 to 3,000 BP. Subsequently, intermittent major explosive eruptions occurred, with subordinate lava flows and small pyroclastic flows. Summit eruptions dominated from 3,000 to 2,000 BP, after which flank vents were active. The extensive basaltic lava flows from the summit and some of the more than 100 flank cones and vents blocked drainages against the Tertiary Misaka Mountains on the north side of the volcano, forming the Fuji Five Lakes. The last eruption of this dominantly basaltic volcano in 1707 ejected andesitic pumice and formed a large new crater on the east flank.

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Type:StratovolcanoLatest Eruptions: Between 1600 and 1700; about 1800-1802; 1831; 1835; 1842-44(?); about 1847-1854; 1857; 1980-? 3. Present thermal activity: Strong steaming Remarks: Continuous intermittent volcanic activity since 1980 2 ... Occasional eruptions of steam and ash; occasional pyroclastic flows; intermittent extrusion of dome-forming

Location: Washington Latitude: 46.20 N Longitude: 122.18 W Height: 2,549 Meters (8,364 feet (9,677 feet before May 18, 1980))

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In 1943 a cinder cone started growing on a farm near the village of Paricutin in Mexico. Explosive eruptions caused by gas rapidly expanding and escaping from molten lava formed cinders that fell back around the vent, building up the cone to a height of 1,200 feet. The last explosive eruption left a funnel-shaped depression called a crater at the top of the cone. After the excess gases had largely dissipated, the molten rock quietly poured out on the surrounding surface of the cone and moved downslope as lava flows. This order of events -- eruption, formation of cone and crater, lava flow -- is a common sequence in the formation of cinder cones.

  • During nine years of activity Paricutin built a prominent cone, covered about 100 square miles with ashes, and destroyed the town of San Juan. Geologists from many parts of the world studied Paricutin during its lifetime and learned a great deal about volcanism, its products, and the modification of a volcanic landform by erosion.
  • ... The eruptive activity of Paricutin Volcano in 1947 demonstrated a "Vulcanian"-type eruption, in which a dnese cloud of ash-laden gas explodes from the crater and rises high above the peak. Steaming ash forms a whitish cloud near the upper level of the cone.
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