Earthquakes

EarthquakeWhat is an earthquake?

Earthquakes are the shaking, rolling or sudden shock of the earth’s surface. They are the Earth's natural means of releasing stress. More than a million earthquakes rattle the world each year. Earthquakes can be felt over large areas although they usually last less than one minute. Earthquakes cannot be predicted - although scientists are working on it!

 

Earthquake destructionWhat causes an earthquake?

There are about 20 plates along the surface of the earth that move continuously and slowly past each other. When the plates squeeze or stretch, huge rocks form at their edges and the rocks shift with great force, causing an earthquake.

Think of it this way: Imagine holding a pencil horizontally. If you were to apply a force to both ends of the pencil by pushing down on them, you would see the pencil bend. After enough force was applied, the pencil would break in the middle, releasing the stress you have put on it. The Earth's crust acts in the same way. As the plates move they put forces on themselves and each other. When the force is large enough, the crust is forced to break. When the break occurs, the stress is released as energy which moves through the Earth in the form of waves, which we feel and call an earthquake.

What is a fault?

A fault is an area of stress in the earth where broken rocks slide past each other, causing a crack in the earth's surface.

Learn Earthquake Words

EPICENTRE - The point on the earth's surface directly above the source of the earthquake.

SEISMIC WAVES - The energy created by the quake travels in waves from the epicenter, where they are the strongest. The waves shake buildings, structures and the earth vertically, causing them to move horizontally!

RICHTER SCALE - A measurement of an earthquake's intensity. Each one-point increase on the scale indicates ten times the amount of shaking and 33 times the amount of energy. The energy released by a large earthquake may be equal to 10,000 times the energy of the first atomic bomb.

SEISMOGRAPH - A seismograph is an instrument used for recording the intensity and duration of an earthquake.

Richter Scale 
4 Minor Earthquake
5 Moderate Earthquake
6 Strong Earthquake
7 Major Earthquake
8 Great Earthquake

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