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Published byBritney McLaughlin Modified over 9 years ago
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Volcanoes Chapter 5 S6E5: Convection currents cause plate movement which causes geologic activity such as volcanoes.
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A weak spot in Earth’s crust where magma comes up to the surface
What is a VOLCANO? A weak spot in Earth’s crust where magma comes up to the surface
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Where are most of Earth’s major volcanoes located?
In belts around the Earth’s continents and oceans along plate boundaries One major belt is known as the Ring of Fire, located around the rim of the Pacific Ocean
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Volcanoes at Divergent Boundaries
May form in the ocean at mid-ocean ridges May form on continents at rift valleys
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Example: Great Rift Valley in East Africa
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Volcanoes at Converging Boundaries
Form where 2 plates collide: Oceanic Continental Oceanic Oceanic The resulting volcanoes create a string of islands called an Island Arc
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Examples of Island Arcs: The Aleutian Islands
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Another Example of an Island Arc: The Carribean Islands
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Volcanic Hot Spots A volcano forms above a Hot Spot when magma erupts through the crust and reaches the surface
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Oceanic Hot Spot: The Hawaiian Islands
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Continental Hot Spot: Yellowstone National Park, Wyoming, USA
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Volcanic eruption vary depending on the viscosity of the magma
What is viscosity? The resistance of a liquid to flow. The greater the viscosity, the thicker the flow Depends on the amount of silica (from 50% - 70%)
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Quiet Eruption Volcano erupts quietly
Low silica magma has low viscosity and flows easily Example: The Hawaiian Islands
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Explosive Eruption Volcano erupts violently
High silica magma, high viscosity, thick and sticky, does not flow – builds up pressure Example: Mt Saint Helens Mount St. Helens about noon on May 18, 1980 after being dormant for 123 years.
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Pyroclastic Flow Volcano erupts violently
Hurls out a mixture of hot gases, ash, cinders, & bombs Example: Mayon Volcano, Philippines
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Three Main Types of Volcanoes:
1. Shield Volcano 2. Cinder Cone Volcano 3. Composite Volcano
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Shield Volcano Gradual, build-up of lava Wide, gently sloping mountain
Example: Hawaiian Islands Notice the shapes of the shields??? Hummm…
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Erupts violently, producing ash, cinders, and bombs
Cinder Cone Volcano Erupts violently, producing ash, cinders, and bombs Loose materials build up around the vent in a steep cone-shaped mountain Example: Pariciutin, Mexico
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Cinder Cone Volcano
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Composite Volcano Lava alternates with layers of ash in explosive eruptions Tall, cone-shaped mountain Examples: Mt. Fuji, Japan and Mt. Saint Helens, Washington, USA
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Composite Volcanoes
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Mt. Saint Helen’s Before & After eruption
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Comparing Shield & Composite Volcanoes
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Comparing the shapes of Volcanoes!
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Check out this volcano link…
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Huge hole left by the collapse of a volcanic mountain
What is a Caldera? Huge hole left by the collapse of a volcanic mountain
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Geothermal Activity Hot springs & geysers are types of geothermal activity often found in areas of past or present volcanic activity
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What are hot springs? They form when groundwater is heated by nearby magma or hot rock deep underground
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Which one is a geyser?
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Seriously, what is a geyser?
A fountain of water and steam that erupts from the ground Example: Old Faithful at Yellowstone National Park It erupts ‘faithfully’ every 33 – 93 minutes
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Experimenting with Volcanic Eruptions
Volcano Info…build & erupt a volcano…have fun!
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