An enumeration district is a geographic area determined for purposes of taking the census. In one city there may be many enumeration districts, so once you enter a city, county, or state, you can narrow your results by entering street level information, or investigate enumeration district maps, or descriptions.
P wave. 1. a longitudinal earthquake wave that travels through the interior of the earth and is usually the first conspicuous wave to be recorded by a seismograph. Also called primary wave. Compare L wave, S wave. The P wave is admitted to be the wave of auricular contraction. p wave.
Traveling through the interior of the earth, body waves arrive before the surface waves emitted by an earthquake. These waves are of a higher frequency than surface waves. P Waves. The first kind of body wave is the P wave or primary wave. This is the fastest kind of seismic wave, and, consequently, the first to 'arrive' at a seismic station. The P wave can move through solid rock and fluids, like water or the liquid layers of the earth.