| A | B |
|---|
| Mercalli scale | a scale that rates earthquakes according to their intensity and how much damage they cause at a particular place |
| magnitude | the meaurement of an earthquake's strength based on seismic waves and movement along faults |
| moment magnitude scale | a scale that rates earthquakes by estimating the total energy released by an earthquake |
| seismologist | a scientist who studies earthquakes |
| seismogram | a record of seismic waves recorded by a seismograph |
| Richter scale | the scale used to measure the strength of earthquakes; it rates an earthquake's magnitude based on the size of the seismic waves |
| focus | the underground point of an earthquake, where the rocks break and move |
| epicenter | the point on the surface directly above the focus of the earthquake |
| earthquake | the shaking and trembling that results from the sudden movement of part of the Earth's crust |
| Primary (P) wave | a push-pull seismic wave, which can travel through solids, liquids, and gases; the fastest |
| Secondary (S) wave | a side-to-side earthquake wave, which can travel through solids but not through liquids and gases; slower than P but faster than L |
| Surface (L) wave | an up-and-down earthquake wave; slowest and it causes the most damage |
| seismic wave | an earthquake wave |
| seismograph | an instrument that detects and measures seismic waves |
| tsunami | a giant sea wave produced by an earthquake |
