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Types of Volcanoes

Shield Volcanoes

Low silica level Low viscosity Lava level of gas can vary Low to medium explosivity Flattened mound Resembles a warrior’s shield

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Mauna Loa, Hawaii

Effusive (gushing) Eruptions Effusive eruptions are

characterized by outpourings of lava on to the ground.

Aa – chunks of very angular pieces of lava

Pahoehoe – smooth or “ropey”

Hawaii

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Composite/Stratovolcano

High in silica High viscosity magma High levels of gas Highly explosive Cone shaped Formed by layers of lava and ash

Mt. Rainier, Washington

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Three products from an explosive eruption– Ash fall– Pyroclastic flow– Pyroclastic surge

Explosive Eruptions

Pyroclastic flows on Montserrat, buried the capital city.

Cindercones

Low silica lava High levels of gas “Fire-fountain” eruptions Commonly found on the flanks of shield

volcanoes Made from a pile of rock pieces Structurally weak

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Pu'u ka Pele, Hawaii(on the flanks of Mauna Loa)