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2022 Sci 8 Ch. 6
Earthquakes
| Term | Definition |
|---|---|
| Seismometer | An instrument that measures earthquake waves |
| earthquake | Any shaking of the earth |
| stress | A force exerted inside a material |
| compression | A contact force that acts to squeeze or crush an object or substance |
| tension | Force that act to pull an object apart |
| shear | Force acting in opposite directions on different parts of the same object |
| Buoyant | An upward force on a less dense object in a denser material |
| Divergent | Boundaries where the plate sections are moving apart |
| Convergent | Boundaries where the plates are moving towards each other |
| Joint | Crack in a rock |
| fault | When the sections of a rock on opposite sides of the crack move relative to each other |
| strike | Helps determine the direction of a fault |
| dip | Angle of a fault down from the horizontal |
| Dipslip | A fault where the fault’s motion is parallel to its dip |
| Strikeslip | A fault where the only motion along the fault is horizontal |
| Pwaves | First, “Primary” waves |
| Swaves | Second waves, can’t pass through liquids |
| Surfacewaves | Most destructive waves |
| focus | Center of earthquake’s activity, deep underground |
| epicenter | Spot on earth’s surface directly above the focus |
| RichterScale | Strengths of earthquakes are reported using this |
| magnitude | Indicates energy released by the earth movement |
| intensity | Measure of how much damage actually results from an earthquake |