What Is Seismology? Seismology is the study of earthquakes and seismic waves that move through and around the earth. A seismologist is a scientist who studies earthquakes and seismic waves.

What Are Seismic Waves? the waves of energy caused by the sudden breaking of rock within the earth or an explosion

Characteristics of seismic waves . The composition of the material through which P waves and S waves travel affects the speed and direction of the waves. The change in speed and direction is how scientists concluded the different layers had different physical properties. For example, P waves travel fastest through materials that are very rigid and are not easily compressed. By studying the speed and direction of seismic waves, scientists can learn more about the makeup and structure of Earth’s interior. The amplitude of a wave is the height of the wave

Body waves- Surface waves- Types of Seismic Waves Body waves can travel through the Earth's interior Higher frequency than surface waves Surface waves- Surface waves can only travel along the surface of the Earth

Body Waves P-wave (primary, compression) First to arrive Can move through solid and liquid particles move in the same direction that the wave is moving in, which is the direction that the energy is traveling in, and is sometimes called the 'direction of wave propagation'. Push and Pull S-wave (secondary, transversal) Arrives second (slower than P-waves) Can only move through solid (this is how scientists discovered the outer core was liquid) S waves move rock particles up and down, or side-to-side--perpendicular to the direction that the wave is traveling in (the direction of wave propagation).

P- Waves

S- Waves

Surface waves Rayleigh Waves Travels along the Earth's surface Love waves Travels along the Earth's surface Fastest surface wave Moves in a side to side direction Rayleigh Waves Travels along the Earth's surface Rolls along the ground like a wave rolls along the ocean

Comparison of waves p. 321 in textbook Direction of the wave

Speed and Direction of Waves P waves can travel through all of the layers, the speed and direction of the waves change as the waves pass through each of Earth’s layers. The waves bend in such a way that P-wave shadow zones form. S waves cannot pass through the liquid outer core creating an even larger S-wave shadow zone.

Shadow zones P- waves S-waves . A shadow zone is an area on the Earth's surface where no direct seismic waves from a particular earthquake can be detected