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30 Cards in this Set
- Front
- Back
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volcano
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A weak spot in the crust where molten material, or magma comes to the surface
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Magma
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A mixture of rock-forming, gases, and water from the mantle
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Ring of Fire
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A belt of volcanoes that rim the Pacific Ocean
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Where do volcanoes form?
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1. Converging Plate Boundaries
2. Diverging Plate Boundaries 3. Hot Spots |
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Converging Plate Boundaries
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2 Types:
1. Oceanic-Ocanic Crust 2. Oceanic-Continental Crust Both form when one plate (denser) gets subducted or pushed down into the mantle creating a DEEP OCEAN TRENCH. The subducted plate melts Forms magma Rises to the surface form a volcano. May form an island arc Example: Andes Mountains in S. America Cascade Mountains in Washington USA (Mt. St. Helens) |
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Diverging Plate Boundaries
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At MID OCEAN RIDGE
The ocean floor pulls apart Lava pours out of the cracks and hardens forming new crust. Example: Iceland & Azors Islands |
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Hot Spots
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An area where magma from deep within the mantle melts through the crust like a blow torch.
The magma hardens underwater gradually new layers harden on top of old layers creating a volcanic island As the plate slowly moves on top of the hot spot, new volcanoes form. Example: Hawaiian Islands |
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Island Arc
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A chain of volcanic islands
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How does magma reach the surface?
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Liquid magma rises from the mantle because it is less dense than the surrounding rock
Gasses inside magma are dissolved. Pressure builds inside the volcano, and eventually it explodes |
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Crater
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A bowl shaped area that forms the top of a volcano around a volcano's vent
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Vent
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an opening through which molten rock and gas leave the volcano
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Magma chamber
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Area where magma collects beneath a volcano
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2 types of volcanic eruptions
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1. Quiet Eruptions
2. Explosive Eruptions |
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Quiet Eruptions
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When lava oozes slowly from the vent. Happens when magma is able to move slowly and freely.
Example: Composite Volcanoes Shield Volcanoes have quiet eruptions |
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Quiet Eruptions produce 2 types of lava
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1. Pahoehoe
2. Aa |
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Pahoehoe Lava
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FAST moving HOT lava
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Aa Lava
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SLOWER moving COOLER lava
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Explosive Eruptions
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When magma is thick
Does not flow out of the crater easily. Pressure builds inside the volcano because the gasses cannot escape. Example: Cinder Cone Volcanoes & Composite Volcanoes have explosive eruptions |
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Pyroclastic flow
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When a volcano hurls out ash, cinders, bombs, and gasses at hundreds of miles an hour.
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3 Stages of a volcano
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1. Active
2. Dormant 3. Extinct |
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Active
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A volcano that IS ERUPTING or shows signs that it MAY ERUPT IN the FUTURE
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Dormant
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A volcano that is NOT ERUPTING currently, but MAY and erupt in the future
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Extinct
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A volcano that is NEVER to erupt again
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3 Types of Volcanoes
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1. Shield
2. Cinder Cone 3. Composite |
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Shield Volcano
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Forms when repeated lava flows gradually during quiet eruptions
Gradually build up a broad, gently sloping volcanic mountain Example: Hawaiian Islands |
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Cinder Cone Volcano
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Steep, cone-shaped hill or mountain formed when volcanic ash cinders & bombs erupt explosively falling around the vent in a cone-shaped pile.
Example: Sunset Crater in Arizona |
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Composite Volcano
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Tall, cone-shaped mountains
Layers of lava alternate with layers of ash Has quiet & explosive eruptions example: Mt. St. Helens in Washington, Mt. Fuji in Japan Example: Mt. St. Helens in Washington Mt. Fuji in Japan |
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Caldera
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Huge hole left by the collapse of a volcanic mountain, due to an enormous eruption
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How does a Caldera form?
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Volcano erupts all magma from the main vent and magma chamber beneath the volcano
Leaves behind a hollow shell With nothing to support it, the top to the magma chamber collapses inward |
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Lava
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Magma that reaches the Earth's surface
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