(See related pages)
Below you will find key words and concepts that you should remember from this chapter.
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| aftershock | Small earthquake that follows a main shock. (See page(s) 395) |
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| Benioff zone | Distinct earthquake zone that begins at an oceanic trench and slopes landward and downward into Earth at an angle of about 30° to 60°. (See page(s) 400) |
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| body wave | Seismic wave that travels through Earth’s interior. (See page(s) 383) |
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| circum-Pacific belt | Major belt around the edge of the Pacific Ocean on which most composite volcanoes are located and where many earthquakes occur. (See page(s) 400) |
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| depth of focus | Distance between the focus and the epicenter of an earthquake. (See page(s) 387) |
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| earthquake | A trembling or shaking of the ground caused by the sudden release of energy stored in the rocks beneath the surface. (See page(s) 380) |
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| elastic rebound theory | The sudden release of progressively stored strain in rocks results in movement along a fault. (See page(s) 380) |
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| epicenter | The point on Earth’s surface directly above the focus of an earthquake. (See page(s) 383) |
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| focus | The point within Earth from which seismic waves originate in an earthquake. (See page(s) 383) |
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| intensity | A measure of an earthquake’s size by its effect on people and buildings. (See page(s) 387) |
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| island arc | A curved line of islands. (See page(s) 400) |
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| Love wave | A type of surface seismic wave that causes the ground to move side to side in a horizontal plane perpendicular to the direction the wave is traveling. (See page(s) 383) |
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| magnitude | A measure of the energy released during an earthquake. (See page(s) 388) |
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| Mediterranean-Himalayan belt | A major concentration of earthquakes and composite volcanoes that runs through the Mediterranean Sea, crosses the Mideast and the Himalaya, and passes through the East Indies. (See page(s) 400) |
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| modified Mercalli scale | Scale expressing intensities of earthquakes (judged on amount of damage done) in Roman numerals ranging from I to XII. (See page(s) 387) |
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| moment magnitude | An earthquake magnitude calculated from the strength of the rock, surface area of the fault rupture, and the amount of rock displacement along the fault. (See page(s) 388) |
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| P wave | A compressional wave (seismic wave) in which rock vibrates parallel to the direction of wave propagation. (See page(s) 383) |
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| Rayleigh wave | A type of surface seismic wave that behaves like a rolling ocean wave and causes the ground to move in an elliptical path. (See page(s) 383) |
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| Richter scale | A numerical scale of earthquake magnitudes. (See page(s) 388) |
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| seismic sea wave | See tsunami. (See page(s) 395) |
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| seismic wave | A wave of energy produced by an earthquake. (See page(s) 380) |
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| seismogram | Paper record of earth vibration. (See page(s) 386) |
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| seismograph | A seismometer with a recording device that produces a permanent record of Earth motion. (See page(s) 384) |
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| surface wave | A seismic wave that travels on Earth’s surface. (See page(s) 383) |
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| S wave | A seismic wave propagated by a shearing motion, which causes rock to vibrate perpendicular to the direction of wave propagation. (See page(s) 383) |
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| travel-time curve | A plot of seismic-wave arrival times against distance. (See page(s) 386) |
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| tsunami (seismic sea wave) | Huge ocean wave produced by displacement of the sea floor; also called seismic sea wave. (See page(s) 395) |