| A | B |
|---|
| lithosphere | Earth's crust and upper mantle |
| epicenter | point located above an earthquake focus |
| normal fault | tension forces |
| primary wave | seismic wave that causes particles of rock to vibrate in the same direction as the wave is moving |
| convergent | boundary where plates collide |
| modified Mercalli scale | measures the amount of structural and geological damage an earthquake causes; or its intensity |
| surface wave | seismic wave that does the most damage |
| strike-slip fault | shear forces |
| convection currents | cause plate motion |
| focus | point inside Earth where the first movement of an earthquake occurs and energy is released |
| divergent | boundary where plates move apart |
| rifts | long cracks formed as a result of plates that are moving apart |
| transform | boundary where plates grind past each other |
| tectonic plate motion | produces the forces that form volcanoes and cause earthquakes |
| Richter scale | based on measurements of amplitudes of seismic waves |
| reverse fault | compression forces |
| secondary wave | seismic wave that causes particles of rock to vibrate at right angles to the direction in which it is moving |
