A body wave that can pass through all layers of the earth. It is fastest of all seismic waves, traveling at a velocity of 3-4 miles (5-7 kilometers) per second in the crust and 5-6 miles (8-9 kilometers) per second in the upper mantle. Also known as compressional wave; longitudinal wave; primary wave.
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Primary seismic waves. The fastest set of earthquake vibrations. They move through the Earth in compression and expansion motions (much like sound waves move through air). Called primary because they are the first recorded at a seismograph. Primary waves are able to travel through both solids and liquids.
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