| A | B |
|---|
| focus | spot underground where earthquake begins |
| epicenter | spot on surface with strongest shaking |
| fault | crack in Earth's crust where earthquakes occur |
| shallow earthquake | focus less than 60 km below surface |
| intermediate earthquake | focus between 60-300 km below surface |
| deep earthquake | focus more than 300 km below surface |
| L wave | slowest; rolls like ocean wave; only at surface |
| earthquake | movement of plates at a fault due to build-up of stress |
| S wave | secondary; side-to-side shearing motion; most damaging; only moves through solids |
| P wave | primary; fastest wave; compression; moves through all materials |
| Moho | boundary between crust and mantle |
| seismogram | paper recording of earthquake waves |
| seismograph | instrument used to record earthquake waves |
| shadow zone | no seismic waves received here |
| magnitude scale | measures energy released during earthquake |
