1. 10.1 How and Where Earthquakes Occur

2. Causes of Earthquakes What is an Earth quake?
It is the shaking of earth’s crust due to the release of E.
They are caused by strain that builds up at or along lithosphere boundaries.

3. Causes of Earthquakes
Faults – A break in the lithosphere along which movement has occurred. Focus – The area where first movement occurs during an Earthquake. The place where rock begins to move and break. Epicenter – The area directly above the focus.

4. Body Waves
Body Waves – The waves that travel through the Earth from the focus of an Earthquake.

5. Body Waves
P Waves – Squeeze and stretch rock material in the direction of wave movement.

6. Body Waves
S Waves (Shear or secondary waves) – Waves that move perpendicular to the direction of the wave motion. Cannot travel through liquid and gas.

7. Body Waves
**Note**
The speed at which the waves travel is dependent on the material. Less rigid, less dense material will cause slower travel of a wave and vice versa.

8. Surface Waves
Surface waves – Waves that travel along Earth’s surface. When P and S waves reach the Earth’s surface, surface waves are produced.
Rayleigh Waves
Love Waves

9. Surface Waves
Love waves – Causes material to move side to side perpendicular to the direction of the wave.

10. Surface Waves
Rayleigh Waves – Causes material to move in an elliptical pattern. Like ripples in a lake.