Earthquakes and Volcanoes Video
Glossary
Asthenosphere: hot layer of earth’s upper mantle that acts like putty
Breaker: a collapsing wave
Cinder cone: volcanic mountain built of tephra
Composite Cone: volcanic mountain made up of layers of lava and tephra
Continental drift: idea that continents move from one part of the earth to another
Converging boundary: place where two plates moving in different directions meet head on
Core: sample of rock and sediment obtained by drilling into the earth
Crust: top layer of the earth
Diverging boundary: place where two plates of the lithosphere are moving apart and new lithosphere is formed.
Earthquake: trembling of the earth caused by a sudden release of stored energy as land masses are displaced
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Epicenter: point on the earth’s surface directly above the earthquake’s focus
Fault: crack in the earth’s crust along which some movement has occurred
Geothermal energy: energy from heat within the earth’s interior
Inner core: central part of the earth’s core, extending to the earth’s center
Lithosphere: solid outer layer of the earth, including both the crust and upper mantle
Mantle: solid layer of the earth between the outer core and crust
Pilot: large moving section of the lithosphere that contains continents and sea floor
Plate tectonics: theory that solid plates move on top of the putty-like asthenosphere
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Reverse fault: a fault where the rocks above the fault move up

Richter scale: numerical description of the size of seismic waves produced by and earthquake
Seismic wave: vibration produced by an earthquake
Seismograph: instrument that measures and records seismic waves
Shield cone: volcanic mountain with a broad base and gently sloping sides, usually made from lava flows.
Sliding boundary: place where two plates meet and slide past each other
Subduction: pushing of the edge of one plate below the edge of another
Tephra: pieces of cooled lava that are sprayed into the air and fall back to the ground
Tsunami: a giant ocean wave produced by underwater earth movement or volcanic eruption
Volcano: opening in the earth’s crust where melted rock reach the earth’s surface