| A | B |
|---|
| earthquake | sudden trembling of the earth's crust |
| volcano | place where magma reaches the earth's surface |
| P waves | primary seismic waves |
| S waves | secondary seismic waves |
| L waves | surface seismic waves |
| Richter scale | measures intensity and damage of an earthquake |
| seismograph | machine that detects seismic waves |
| seismogram | record of seismic waves |
| seismologist | scientist who studies earthquakes |
| volcanologist | scientist who studies volcanoes |
| magma | hot, molten rock below the earth's surface |
| lava | molten rock that reaches the earth's surface |
| cinder cone volcano | volcano made of layers of cinders |
| shield volcano | volcano made of lava flows |
| composite volcano | volcano made of alternating layers of cinders and lava flows |
| volcanic dust | smallest volcanic particle |
| volcanic ash | volcanic particle about the size of a grain of rice |
| volcanic bombs | large volcanic particles |
