| A | B |
|---|
| earthquake | a movement or trembling of the ground caused by a sudden release of energy when rocks along a fault move |
| elastic rebound | the sudden return of elastically deformed rock to its undeformed shape |
| focus | the location within Earth along a fault at which the first motion of an earthquake occurs |
| epicenter | the point on Earth's surface directly above an earthquake's starting point, or focus |
| body wave | in geology, a seismic wave that travels through the body of a medium |
| surface wave | in geology, a seismic wave that travels along the surface of a medium; has a stronger effect near the surface than in the interior |
| P wave | primary wave or compression wave; seismic wave that causes particles of rock to move parallel to wave direction |
| S wave | secondary wave or shear wave; seismic wave that causes particles of rock to move perpendicular to wave direction |
| shadow zone | an area on Earth's surface where no direct seismic waves from a particular earthquake can be detected |
| fault zone | a region of numerous, closely spaced faults |
| seismograph | an instrument that records vibrations in the ground |
| seismogram | a tracing of earthquake motion that is recorded by a seismograph |
| magnitude | a measure of the strength of an earthquake |
| intensity | in Earth science, the amount of damage caused by an earthquake |
| tsunami | a giant ocean wave that forms after a volcanic eruption, submarine earthquake, or landslide |
| seismic gap | an area along a fault where few earthquakes have occurred recently but where strong earthquakes occurred in the past |
