When earthquake energy is released, seismic waves radiate from the focus (Stein, pp 53-118). Waves of several types are set into motion. The different wave types have different travel velocities and modes of vibration. Initially, two types of waves radiate from the focus:
The P-Waves and S-Waves generate a third type of seismic wave known as large waves (or L-Waves). They radiate along the Earth's surface from the epicenter of an earth quake and are therefore also known as surface waves.
Some Useful Links
Following are some hyperlinks that can further assist with the evaluation and description of seismic waves:
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