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Volcano Vocab
Term | Definition |
---|---|
Shield Volcano | It looks like a warrior's shield laying on the ground. Formed by thick lava flows that move slowly and are not explosive. Most commonly in the largest volcanoes. Ex:Mauna Loa on the Big Island of Hawaii |
Plate Tectonics | The theory that Earth's outer crust (lithosphere) is divided into several plates that glide over the plastic-like and less ridged asthenosphere (upper mantle). |
Composite Volcano | Large symmetrical cones built by alternating layers of lava flows, volcanic ash, cinders and bombs that can create explosive eruptions. Ex: Mount St. Helen's |
Cinder Cone Volcano | Small cones-shaped volcanoes with steep angled sides. Blobs of lava spew into the air during eruptions and fall as cinders on the sides of the volcano. Built over a short period of time. Ex: Sunset crater in Arizona |
Lava Dome Volcano | Lava is too thick to flow a great distance. Lava cools and piles up around the vent. As the dome continues to grow it spills loose fragments down the sides. Sometimes occur within craters of other volcanoes. Ex: Lassen Peak in California |
Secondary Vent | Magma can reach the surface in other areas. |
Magma | Molten rock under the earth's surface. |
Lava | Molten rock above earth's surface. |
Ring of Fire | An active volcanic region where many eruptions and earthquakes take place. |
Island Arc | Created by convergent boundaries. When the two oceanic crusts converge the older submerges beneath the newer one. It then melts and makes its way back up to the surface forming an island arc. |
Hot Spot | Regions of the mantle that are very hot compared to the mantle. This creates a mantle plume which eventually breaks through the crust as a volcano. This usually happens in the middle of a tectonic plate. Ex: Hawaiian Islands |
Magma Chamber | Large underground pool of molten rock sitting underneath the earth's crust. |
Main Vent | The weak point in the Earth's crust where hot magma rises from the magma chamber and reaches the surface. |
Crater | Circular basin or depression. |
Pyroclastic Flow | Fast-moving current of hot gas and rock that moves away from a volcano |
Caldera | A large basin-like depression resulting from the explosion or collapse of the center of a volcano. |
Volcanic Neck | Where the volcano reaches its peak. |
Igneous Intrusion | When lava cools and hardens |
Subduction Zone | When crust moves under or over each other. |
Volcanic Ash | Small pieces of pulverized rock, minerals, and volcanic glass created during eruption. |
Volcanic Bomb | Large projectiles thrown through the air. |
Dormant Volcano | Quiet now but might erupt again |
Extinct Volcano | Unlikely to erupt again |
Dike | Vertical Intrusions |
Sill | Horizontal Intrusions |