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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 |