The alternative name for P-waves is which of the following?

• A. Primary Waves
• B. Secondary Waves
• C. Surface Waves
• D. Tertiary Waves

Answer: (A)

P-waves are the fastest body waves and move by compressing and expanding the material in the direction they travel. Because they arrive first at a seismic station, they’re called primary waves—the name reflects their position in the sequence of arrivals. The other wave types—S-waves (secondary), which shear the ground, and surface waves, which travel along the surface—reach detectors later and behave differently, so the standard term for what P-waves are is Primary Waves. There isn’t a widely used term like “tertiary waves” in seismology.