volcano
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Volcanoes
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Magma Chamber
SideVent
VentCrater
Pipe
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Hot SpotsHot Spots
• Hot spots are caused from pockets of magma that raise up through openings in the crust.
• While the plate moves the magma oozes out, cools, and makes new layers on top of other layers.
• When these layers raise up above the level of the ocean they make islands, for example like the Hawaiian islands.
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Ring of Fire
• Ring of Fire are volcanoes that are located on the edges of the Pacific plate that happen to make a rough ring of volcanoes.
• Ring of fire is where most of the active volcanoes are located.
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Styles of EruptionsStyles of Eruptions
• Eruptions could be either explosive and violent or soft and quiet.
• Explosive volcanoes act like a soda can that has been shaken up.
– Trapped gases like water vapor and CO2 are in the magma and build up pressure until the magma nears the surface and the gases escape all at once forcefully.
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Magma Composition & Composition & Water Content Content
• Magma that is low in silica is very liquidy and makes quiet eruptions (EX: Kilauea in Hawaii)– This lava pours out from sides of volcanoes
called vents. It also pours out from rift zones which are long deep cracks like in Iceland.
• Magma with lots of silica make very violent, explosive eruptions (EX: Mount St. Helens in Washington)
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Forms of VolcanoesForms of Volcanoes
Shield Volcano
– Quiet eruptions spread out silica poor lave in flat layers.
– Have gentle sloping sides.
– Looks like a shield laying down.
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Forms of Volcanoes
• Composite Volcano
– Some volcanoes can be either explosive or quiet. When a volcano erupts explosively then erupt quietly the next time, it makes different layers of tephra and cinders which is why it is called a composite volcano.
– Mount St. Helens is a composite volcano because the Juan de Fuca plate was forced below the North American plate which caused eruptions to be explosive then quiet at different times.