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Earthquakes
| Question | Answer |
|---|---|
| stress | forces per unit of area on a material |
| compression | stress pressing inwards; decreases volume |
| tension | stress pressing outwards; pulls material apart |
| shear | stress that causes material to twist |
| strain | deformation of materials in response to stress |
| fault | fracture or system of fractures along which movement occurs; results from stress and strain |
| focus | point where earthquake originates |
| epicenter | point on Earth’s surface directly above the focus; most damage done here |
| P-Waves | Primary waves squeeze and pull rocks; fastest waves; travel through liquids and solids |
| S-Waves | Secondary waves cause rocks to move at right angles; slower waves; travel through solids only |
| Long Waves | T-Waves or surface waves; slowest waves; travel along the Earth's surface |
| seismogram | record (picture) of the seismic waves; analyzed to find epicenter and damage |