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| 1. | The ____ or S waves of an earthquake are side-to-side vibrations. |
| 2. | An earthquake rated as 4 on the Richter scale is ___ times as powerful as one rated a 3. |
| 3. | An earthquake releases energy in the form of ____ waves. |
| 4. | The point underground at which an earthquake starts. |
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| 5. | Most earthquakes occur along ____ lines, or lines where tectonic plates meet. |
| 6. | The ____ or P waves of an earthquake are back-and-forth vibrations. A person who experiences an earthquake will feel this wave first. |
| 7. | At a ____ fault boundary, two plates move past and away from each other. |
| 8. | At a ____ boundary, plates move towards each other. |
| 9. | The cracks or breaks in the earth's crust. This is where the plates that make up the earth's crust rub against each other. |
| 10. | The ____ or L waves of an earthquake travel on Earth's surface. |
| 11. | These often follow an earthquake. |
| 12. | At a ____ boundary, plates move away from each other. |
| 13. | This moves, in the form of vibrations, in all directions from the focus of an earthquake. |
| 14. | The point on the surface of the earth directly above the focus of an earthquake. |
| 15. | An instrument that detects and records earthquake vibrations. |
| 16. | The form of energy released by earthquakes. |
| 17. | A scale that usually ranges from 1 to 9. This scale is used to indicate the amount of energy an earthquake releases. |
| 18. | A sudden shift or movement of the earth's crust. |
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