High School Earth Science: Earthquakes - The Nature of Earthquakes — Flashcards

Energy is transmitted in waves. The energy from earthquakes is transmitted in waves called seismic waves. There are two basic types of seismic waves: body waves and surface waves.    
Body waves are seismic waves that travel through the solid body of Earth. They originate at the focus of an earthquake and travel outward in all directions. Body waves include P-waves (primary waves) and S-waves (secondary waves). P-waves can travel through solids, liquids, and gases. They travel faster than any other type of seismic waves, so they are always the first waves to arrive at seismometers. P-waves move rocks forward and backward in the same direction that the waves are traveling. S-waves can travel only through solids. They travel more slowly than P-waves, so they reach seismometers after P-waves. S-waves move rocks up and down perpendicular to the direction that the waves are traveling.    
Surface waves travel along the ground rather than through Earth. They travel outward from an earthquake’s epicenter rather than its focus. They are the slowest of all seismic waves. Surface waves include Love waves and Rayleigh waves. Love waves cause the ground to move back and forth perpendicular to the direction that the waves are traveling. Rayleigh waves cause the ground to move in a circular motion. The combined ground movements of Love and Rayleigh waves give the surface of the ground a rolling motion. This motion causes most of the damage in an  earthquake.