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VOLCANOES.

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Presentation on theme: "VOLCANOES."— Presentation transcript:

1 VOLCANOES

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3 Mount Fuji Mount Fuji

4 Mauna Loa

5 Volcanic Landforms Key concepts: Volcanic landforms vary with
- tectonic setting, - composition of magma conditions during eruption, - volume of eruption.

6 Types Shield Composite Fissure Cinder

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8 ShieldVolcanoes low viscosity basaltic lava flows.
- large volcanoes with broad summit areas and low-sloping sides low viscosity basaltic lava flows. A good example of a shield volcano is the Island of Hawaii (the "Big Island").

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16 Composite Volcanoes built by multiple eruptions, sometimes recurring over hundreds of thousands of years, sometimes over a few hundred. Andesite magma, the most common but not the only magma type, tends to form composite cones. built mostly of fragmental debris, with a structural framework of dikes and sills that knits together the voluminous accumulation of volcanic rubble.. Composite cones can grow to such heights that their slopes become unstable.

17 Mayon

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22 Mount Rainier

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25 Mount Fuji Mount Fuji

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30 Cinder cones Cinder cones are mounds of basaltic fragments.
Streaming gases carry liquid lava blombs into the atmosphere that rain back to earth around the vent to form a cone.

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33 Calderas are circular to oblong depressions formed by collapse of the central vent during the extrusion of pyroclastic materials. Their diameters are many times larger than those of associated vents.

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38 Domes Lava domes form by the slow extrusion of highly viscous silica-rich magma Domes can be solitary volcanoes, form in clusters, grow in craters or along the flanks of composite cones. A dome has been growing slowly within the crater of Mount St. Helens since the eruption of Domes have also filled the crater of Mt. Pelée, Martinique, etc.

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41 List of Volcanic Hazards
Pyroclastic Density Currents (pyroclastic flows and surges) Structural Collapse: Debris flow- Avalanches Dome Collapse and the formation of pyroclastic flows and surges Lava flows Tephra fall and ballistic projectiles Volcanic gas Tsunamis

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43 Mount St Helens 1980


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