What do seismograms look like at increasing distances from epicenter?
A companion animation titled "Four-station Seismograph Network Records a Single Earthquake" showed the buildings and cows bouncing and rolling above the surface of the Earth. The intent was to illustrate the nature of wave movement, not mimic reality. This version has no bounce. The cow is just for fun and to emphasize that seismic waves traveling away from an earthquake occur everywhere, not just at seismic stations. A person would feel a large earthquake only at station A near the epicenter. Stations B, C, D, and the cow are too far from the earthquake to feel the seismic waves. Both the scale of the buildings (and cow) and the amplitude of the movements are exaggerated. The cartoonish amplified ground motions show the compressive (up-down in this case) P wave, the shearing (back-forth) S wave, and the rolling surface wave motions recorded by sensitive instruments. Notice that Station D does not record an S wave because shear waves cannot travel through Earth's liquid outer core.
- Seismic stations at varying distances from a large earthquake have signature seismograms
- Seismic stations record the compressive, shearing, and rolling behavior of different seismic waves
- Seismograms indicate the travel time of P and S waves
- Seismograms yield information about the shadow zones