The P-wave energy causes the ground to move in a compressional motion in the same direction that the wave is traveling. The S-wave energy causes the ground to move in a shearing motion perpendicular to the direction of wave movement. Rayleigh and Love waves are the two types of surface waves. Rayleigh wave energy causes a complex heaving or rolling motion, while Love wave energy causes a sideways movement. The combination of Rayleigh and Love waves results in ground heave and swaying buildings.
Surface waves cause the most devastating damage to buildings, bridges, and highways.
Detecting, locating, and measuring earthquakes Several thousand stations monitor earthquakes all over the world. Each station contains an instrument, called a seismograph , used to detect arrival times and record seismic waves. The seismometer electronically amplifies wave motion. The graph on which seismic waves are recorded is called a seismogram. The amplitude of the recorded seismic wave is the vertical distance between the crest and trough of the waveform, therefore, the larger the earthquake, the greater the amplitude of the earthquake.