1. Earthquakes

2. Causes of Earthquakes
An earthquake is a shaking of the Earth’s crust cause by a release of energy. Earthquakes happen because – eruption of a volcano, collapse of a cavern, impact of a meteor Most major earthquakes are caused by the movement of two faults (Fault  a break in the lithosphere {crust} between two lithospheric plates)

3. Focus ……
The point where the first movement occurs

4. Epicenter…..
The point on Earth’s surface directly above the focus

5. Waves
Body waves  waves that travel from the focus of the earthquake through the Earth

6. P-waves
P waves  primary waves, compressional waves  squeeze and stretch rock materials as they pass through Earth; p-waves can travel through any material….solid rock, magma, ocean water, air

7. S-Waves
S waves  secondary waves, shear waves  cause particles of rock material to move at right angles to the direction in which the waves are traveling; s-waves can ONLY travel through solid material, NOT liquids or gases

8. Surface Waves
Earthquake waves that travel along Earth’s surface. Love waves  cause particles of material to move from side to side, in a direction PERPENDICULAR to the waves’ direction of travel Rayleigh waves  travel slower than Love waves; material moves in a elliptical pattern

9. Seismograph

10. Seismograph
Detects and records waves produced by earthquakes

11. Magnitude
Strength of an earthquake Charles Richter (1935)  Richter Scale ; each level on the scale is 31 times greater than the level before it

12. Earthquake Hazards……
Ground shaking and foundation failure (buildings falling over, completely collapsing) Liquefaction  loose soil that moves like a liquid instead of a solid Aftershocks  smaller earthquakes that follow after the main earthquake Fire Tsunami  underwater earthquakes that create huge ocean waves