| A | B |
|---|
| aftershock | tremor that follows and is smaller than a major earthquake |
| earthquake | vibration of the earth's crust |
| elastic rebound theory | theory that rocks that are strained past a certain point will fracture and spring back to their original shape |
| epicenter | point on the earth's surface directly above the focus of an earthquake |
| fault zone | group of interconnected faults |
| focus | area along a fault at which slippage occurs, initiating an earthquake |
| intensity | amount of damaged caused by an earthquake |
| magnitude | a measure of the energy released by an earthquake; described as the amount of ground motion |
| Mercalli scale | scale that expresses the intensity of an earthquake with a Roman numeral and a description |
| microquake | earthquake with a magnitude less than 2.5 on the Richter scale |
| P wave | primary wave; the fastest wave generated by an earthquake and the first to be recorded by a seismograph |
| Pacific Ring of Fire | major earthquake zone that forms a ring around the Pacific Ocean |
| S wave | secondary wave; a wave fenerated by an earthquake and the second to be recorded by a seismograph |
| seismic gap | zone of rock in which a fault is locked and unable to move and in which no major earthquake has occurred for a long period of time |
| seismograph | instrument used to detect and record seismic waves |
| surface wave | the slowest moving seismic wave generated by an earthquake and the last to be recorded by a seismograph |
| tsunami | giant ocean wave that often occurs after a major earthquake with an epicenter on the ocean floor |
