LECTURE 5 - LECTURE 5 VOLCANISM What is a volcano? From...

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LECTURE 5 VOLCANISM What is a volcano? •From word Vulcan , Roman god of fire and metal working Geologic landform where molten rocks from the planet’s interior are ejected to the surface Generic Volcano Features Central Vent Summit Crater Edifice Magma Chamber Parasitic Cones Fumaroles How do we know if a volcano is active? - Active – erupted during the last 10,000 yrs. - Inactive – no activity during the last 10,000 yrs. - Potentially active - volcanic activit between 10 ka – 1.65 Ma Types of volcanoes 0. Based on morphology and building materials 1
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Types of Volcanos Sheild volcanos – produced by the accumulation of fluid basaltic lavas and exhibit the shape of a broad slightly domed structure that resembles a warrior’s shield (grown up mostly from the deep-ocean level, not all) Ex. Mauna Loa (largest volcano), Kilauea Cinder Cones (also called Scoria Cones) – built from ejected lava fragments that take on the appearance of cinde4rs or clinkers as they begin to harden while in flight, usually the product of a single eruptive episode that sometimes lasts only a few weeks and rarely exceeds a few years, once this event ceases the magma in the pipe connecting the vent to the magma chamber solidifies and the volcano never erupts again = short lifespan Ex. Paricutin Composite Cones (stratovolcanoes) – large, nearly symmetrical structure composed of both lava and pyroclastic deposits, product of gas-rich magma having an andesitic composition, The growth of a typical composite cone begins with both pyroclastic material and lava being emitted from a central vent. As the structure matures, lavas tend to flow from fissures that develop on the lower flanks of the cone. This activity may alternate with explosive eruptions that eject pyroclastic material from the
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This note was uploaded on 01/23/2011 for the course GEO 11 taught by Professor Lim during the Fall '10 term at University of the Philippines Diliman.

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LECTURE 5 - LECTURE 5 VOLCANISM What is a volcano? From...

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