1. What Causes Earthquakes?
As Earth’s plates scrape against each other, stress builds up along faults.
A fault is a break in the Earth’s crust.

2. Earthquakes Focus: Where earthquake starts
Epicenter: Spot on the surface
directly over the focus

3. Earthquake waves All Earthquakes give off energy in the form of waves.
Earthquake waves are called seismic waves
Two types of seismicwaves
P Waves
S Waves

4. Earthquake waves (Seismic waves)
Longitudinal waves are called Primary waves (p-waves)
They move faster than secondary waves
Transverse waves are called secondary waves (s-waves)
They move more slowly than p-waves

5. Waves Longitudinal waves
Matter in the medium moves back and forth along the same direction that the wave travels.

6. Seismic Waves Transverse waves
Particles in the medium moves at right angles to the direction of the wave.