| Word |
Definition |
| focus | The point beneath Earth's surface where rock breaks under stress and causes an earthquake. |
| epicenter | The point on Earth's surface directly above where rock inside Earth has broken. |
| seismic wave | A vibration that travels through Earth carrying the energy released during an earthquake. |
| P wave | A type of seismic wave that compresses and expands the ground. |
| S wave | A type of seismic wave that moves the ground up and down or side to side. |
| surface wave | A type of seismic wave that moves slower, but causes the most destruction. |
| seismograph | A device that records ground movements caused by seismic waves as they move through Earth. |
| magnitude | The measurement of an earthquake's strength based on seismic waves and movement along faults. |
| Mercalli scale | A scale that rates earthquakes according to their intensity and how much damage they cause. |
| Richter scale | A scale that rates seismic waves as measured by a particular type of mechanical seismograph. |
| moment magnitude scale | A scale that rates earthquakes by estimating the total energy released by an earthquake. |
| liquefaction | The process by which an earthquake's violent movement suddenly turns loose soil into liquid mud. |
| aftershock | An earthquake that occurs after a larger earthquake in the same area. |
| tsunami | A large wave produced by an earthquake on the ocean floor. |
| base-isolated building | A building mounted on bearings designed to absorb the energy of an earthquake. |
