Earthquakes and Volcanoes

Front

Mantle Noun

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[man-tl]

Back

Mantle

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The layer of soft, molten rock between the Earth's crust and core, making up the majority of Earth's volume.

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Example: This diagram shows the Mantle as the thick layer of rock located between Earth's thin outer crust and its hot core.

Front

Convection Current Noun

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[kuhn-vek-shuhn kur-uhnt]

Back

Convection Current

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The movement of fluid, driven by heat within the Earth's mantle, that is the driving force behind plate tectonics.

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Example: Heat from the Earth's outer core causes mantle material to rise. It then cools and sinks, creating a circular flow that moves tectonic plates.

Front

Continental Drift Noun

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[kon-tuh-nen-tl drift]

Back

Continental Drift

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The historical theory that continents are slowly shifting their positions over the Earth's surface over geological time.

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Example: This diagram shows how the ancient supercontinent Pangaea broke apart, and its pieces (the continents) slowly drifted to their current locations over millions of years.

Front

Pangaea Noun

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[pan-jee-uh]

Back

Pangaea

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The name of the supercontinent that existed about 200 million years ago, before it broke apart into today's continents.

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Example: This diagram shows the ancient supercontinent Pangaea, labeling how modern continents like North America and Africa were once joined together before breaking apart.

Front

Subduction Noun

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[suhb-duhk-shuhn]

Back

Subduction

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The process at a convergent plate boundary where one tectonic plate moves under another and sinks into the mantle.

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Example: This diagram shows a denser oceanic crust plate sliding underneath a continental crust plate, a process called subduction, which forms an ocean trench.

Front

Divergent Boundary Noun

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[dahy-vur-juhnt boun-dree]

Back

Divergent Boundary

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A location where two tectonic plates are moving away from each other, a process which often creates new crust.

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Example: This diagram shows two oceanic crust plates moving apart, which is a divergent boundary. Magma from below rises to fill the gap, creating new crust.

Front

Convergent Boundary Noun

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[kuhn-vur-juhnt boun-dree]

Back

Convergent Boundary

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A location where two tectonic plates are moving toward each other, resulting in subduction or continental collision.

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Example: Two tectonic plates collide, and one plate slides underneath the other, a process that can form volcanoes.

Front

Transform Boundary Noun

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[trans-fawrm boun-dree]

Back

Transform Boundary

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A location where two tectonic plates slide horizontally past one another, often causing earthquakes along a fault line.

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Example: This diagram shows two tectonic plates sliding horizontally past each other. This movement along the boundary, called a fault, builds up stress that causes earthquakes.

Front

Fault Noun

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[fawlt]

Back

Fault

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A fracture or zone of fractures in the Earth's crust along which there has been significant displacement or movement.

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Example: This diagram shows a fault, a crack in the Earth's crust where rock layers have shifted, causing an earthquake to start at the hypocenter.

Front

Hypocenter Noun

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[hahy-poh-sen-ter]

Back

Hypocenter

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The point within the Earth where an earthquake rupture starts, which is also commonly known as the focus.

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Example: This diagram shows the hypocenter is the point deep inside the Earth where an earthquake begins, directly below the epicenter on the surface.