| A | B |
|---|
| earthquake | causes vibrations in the ground that result from movement along breaks in Earth’s lithosphere |
| epicenter | location directly above the focus of an earthquake |
| fault | break in Earth’s lithosphere where one block of rock moves toward, away from, or past another |
| focus | location where rocks first move along a fault and seismic waves originate |
| primary wave | P-wave; fastest-moving type of seismic wave; causes particles in the ground to move in a push-pull motion |
| secondary wave | S-wave; causes particles in the ground to move side to side and up and down at right angles relative to the direction the wave travels |
| seismic wave | travels as vibrations on and in Earth |
| seismogram | graphical illustration of seismic waves |
| seismologist | scientist who studies earthquakes |
| seismometer | measures and records ground motion and the distance and direction seismic waves travel |
| surface wave | causes particles in the ground to move up and down, in a rolling motion. |
| cinder cone | small, steep-sided volcano that erupts gas-rich, basaltic lava |
| composite volcano | large, steep sided volcano that results from explosive eruptions of andesitic and rhyolitic lavas along convergent plate boundaries |
| hot spot | volcano that is not associated with a plate boundary |
| lava | molten rock that erupts onto Earth’s surface |
| magma | molten rock below Earth’s surface |
| shield volcano | large volcano with gentle slopes of basaltic lava; located along divergent plate boundaries and oceanic hot spots |
| viscosity | liquid’s ability to flow |
| volcanic ash | tiny particles of pulverized volcanic rock and glass |
| volcano | vent in Earth’s crust through which molten rock flows |
