1. Lesson 2: “When the Earth Shakes” Vocabulary

2. Body Wave – an earthquake wave that travels through the body of the earth rather than on its surface. Examples are P-wave and S-wave.

3. P-wave – a primary (compressional) earthquake wave that travels through the body of the earth; so named because it is the first wave to reach a seismograph station during an earthquake.

4. S-wave – a secondary earthquake wave; so named because it travels slower than a primary wave and is the second wave to reach the seismograph station after an earthquake. It travels through the body of the earth as a series of crests and troughs.

5. Surface wave – an earthquake wave that travels on or near the surface of the earth.