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Related to P wave: T wave
P wave[′pē ‚wāv]
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.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.