| A | B |
|---|
| seismograph | an instrument used to record the movement of the earth |
| faults | fractures in the earth's crust |
| tsunami | an earthquake on the ocean floor |
| 30 seconds | an earthquake occurs this often |
| Alaska | the state that has the most earthquakes |
| California | the state that has the most damaging earthquakes |
| Richter Scale | measures the magnitude of an earthquake |
| seismologist | a person who studies earthquakes |
| plates | the jugsaw puzzle pieces of earth's crust |
| divergent movement | when earth's plates move away from each other |
| Mercalli Scale | based solely on observation |
| Florida, North Dakota | the two states that have the least number of earthquakes |
| lateral | when earth's plates move past each other |
| earthquake | the sudden, sometimes violent movement of the earth's surface |
| convergent movement | when the earth's plates move into each other |
| P and S waves | the two kinds of seismic waves produced by an earthquake |
| Chile | the world's largest earthquake on record occured here |
| P waves | the faster of the two seismic waves |
| 1902 | the year the Mercalli Scale was invented |
| 7 minutes | the maximum length of time ever recorded for an earthquake |
