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)

Causes of Earthquakes

The point where the first movement occurs

Focus ……

The point on Earth’s surface directly above the focus

Epicenter…..

1. Body waves waves that travel from the focus of the earthquake through the Earth

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

P-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

S-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

Surface Waves

Seismograph

Detects and records waves produced by earthquakes

Seismograph

Strength of an earthquake

Charles Richter (1935) Richter Scale ; each level on the scale is 31 times greater than the level before it

Magnitude

Ground shaking and foundation failure (buildings falling over, completely collapsing)

Liquefaction loose soil that moves like a liquid instead of a solid

http://www.youtube.com/watch?v=j0sLyJpfTE8

Aftershocks smaller earthquakes that follow after the main earthquake

http://www.youtube.com/watch?v=Z7eABGpOHv8

Fire

http://www.youtube.com/watch?v=f5xt8oQTApE

Tsunami underwater earthquakes that create huge ocean waves

http://www.youtube.com/watch?v=k8IAgUNr6x4

Earthquake Hazards……