EES 100 test 2 study guide

EES 100 test 2 - Volcanoes Types of Volcanoes Shield Volcano o Largest type of volcano gentle arch or shield shape with shallow slopes built up of

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Volcanoes Types of Volcanoes Shield Volcano o Largest type of volcano; gentle arch, or shield shape, with shallow slopes; built up of many lava flows o Common in Hawaiian Islands, Iceland, and some islands in the Indian Ocean o Low silica content of magma, low viscosity, magma forms basalt o Lava flows, tephra ejections Composite Volcano o Cone-shaped; steep sides; built up of alternating layers of lava flows and pyroclastic deposits o Washington (Rainier, St. Helens), Japan (Fuji) o Intermediate silica content of magma, intermediate viscosity, magma forms Andesite o Combination of lava flows and explosive activity Responsible for most of volcanic hazards causing death and destruction in our history Volcanic Domes o Dome shaped o Eastern California (Lassen) o High silica content of magma, high viscosity, magma forms Rhyolite o Highly explosive Cinder Cones o Cone shaped; steep sides; often with summit crater; relatively small o Found near larger volcanoes or along normal faults; Central Mexico (Paricutin cinder cone), Springerville, Arizona o Low silica content of magma, low viscosity, magma forms Basalt o Tephra (mostly ash) ejection Lava: molten material produced from a volcanic eruption, or rock that forms from solidification of molten material Ash: unconsolidated volcanic debris, less than 4 mm in diameter, physically blown out of a volcano during an eruption Tephra: any material ejected and physically blown out of a volcano; mostly ash Cinder, Blocks, Bombs Pyroclastic debris: composed of fragmented magma that has rapidly solidified as it was blown out of a volcano Pyroclastic deposits: refers to particles forcefully ejected from a volcanic vent, explosive in origin, containing volcanic ash particles and those of larger size such as blocks and
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bombs Pyroclastic rocks: consolidated pyroclastic deposits Structural features of volcanoes: o Vents: openings through which lava and pyroclastic debris are erupted at the surface of Earth o May be roughly circular conduits, elongated fissures, or rock fractures o Lava tube: a natural conduit or tunnel through which magma moves from a volcanic event downslope to where the magma may again emerge at the surface o After eruption the tubes are often less as open voids and are a type of cave o Crater: depressions commonly found at the top of volcanoes o Form by explosion or collapse of the upper portion of the volcanic cone; may be flat floored or funnel shaped o Caldera: giant volcanic crater produced by very rare but extremely violent volcanic eruption or by collapse of the summit area of a shield volcano after eruption Types of volcanic hazards: o Lava flow: eruption of magma at the surface of Earth that generally flows downslope from volcanic vents o Pyroclastic flow: rapid subaerial flowage of eruptive material consisting of volcanic gases, ash, and other materials that move rapidly down the flank of a volcano; often form as the result of the collapse of an eruption column o Ash fall:
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This note was uploaded on 04/29/2008 for the course EES 100 taught by Professor Moore during the Fall '08 term at Vanderbilt.

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EES 100 test 2 - Volcanoes Types of Volcanoes Shield Volcano o Largest type of volcano gentle arch or shield shape with shallow slopes built up of

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