SF Table 7.1 shows that P waves have a higher velocity than S waves when traveling through several mineral types. 7.3 that the P wave occurs first, because they travel at a higher velocity. Data from a seismometer, also called a seismogram, shows velocity on the y axis and time on the x axis (Fig. Seismometers measure the vibrations of the ground, relative to a stationary instrument. 7.1 C shows primary or P waves (on top) and secondary or S waves (on bottom) in motion. The motion of secondary waves is perpendicular to the direction of the wave travel, similar to the motion of vigorously shaking a rope (SF Fig. Secondary waves, or S waves, are slower than P waves.

Primary waves, also known as P waves or pressure waves, are longitudinal compression waves similar to the motion of a slinky (SF Fig.

There are two types of seismic waves, primary waves and secondary waves. Seismic waves are vibrations in the earth that transmit energy and occur during seismic activity such as earthquakes, volcanic eruptions, and even man-made explosions. Even though the technology does not exist to travel into all of Earth’s layers, scientists can still learn a great deal about Earth’s structure through seismic waves.

Waves complete 7 list