aftershock

A smaller earthquake that follows a

larger earthquake.

body waves

Waves of energy that travel from the focus of an

earthquake through the material of Earth's body.

S and P waves are 2 examples.

earthquake

The shaking of Earth's crust caused

by a release of energy.

epicenter

The point on the Earth's surface directly

above the focus of an earthquake.

fault

A break in the lithosphere along which movement has occured

focus

The point at which the first movement occurs during and earthquake.

liquifaction

A temporary state in which loose soil and rock materials take on the property of liquid as a result of severe ground shaking.

magnitude

The measure of the amount of energy released in an earthquake.

P wave

Primary Waves

Body waves that stretch and squeeze rock materials as they pass through Earth

S wave

Surface waves - Body waves that occur on the surface

they cause particles to move at right angles

to the direction in which the waves are travelling.

seismic gap

An area along a seismically active fault where no earthquake activity has occurred over a long period of time.

seismograph

An instrument that detects and records waves caused by earthquakes

tsunami

A large ocean or lake wave that results from an underwater earthquake, landslide or volcanic eruption.