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Volcanoes Some Key Terms Plate Tectonics Separating ASH CRATER LAVA SIDE VENT CRUST MAGMA CHAMBER Types of Eruption • • • • Quiet Eruption Explosive Eruption Fissure Flows Intermediate Eruption Quiet Eruption • Low pressure, lava pours out in steady stream and thinly, calm – often called Hawaiian – produces a shield cone - wide base, and gentle, convex slope – gases emitted slowly Shield Cone Explosive Eruption • Great violence, often earthquakes or loud rumblings preceding the eruption • Volcanic bombs (pyroclastics) • Produces a cinder cone - narrow base, steep side • Volcanoes not very high because material is loosely organized – e.g.Krakatoa 1883 Pyroclastic Cinder Cone Fissure Flows • An open crack in solid surface produces a lava plateau or plain many kilometres wide – looks like a ribbon of magma/fire • Produces a flood basalt "cone" or lava plateau Fissure Flows • When it erodes it "candles" like fresh water ice in hexagonal columns!!! – Ireland - Giant's Causeway Fissure Flow Fissure Flow Flood Basalt Intermediate Eruption • Also called Strombolian - a combination of quiet and explosive eruptions • A combination of lava and rock fragments in alternating layers (produces pyroclastics during explosive phase) • Produces a composite cone or stratovolcano Stratovolcano What kind of eruption produces a… Quiet Eruption Explosive Eruption Intermediate Eruption
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