What Causes an Earthquake?

Far beneath us lie the "Tectonic Plates" of the Earth's crust; slow moving and huge, these 50 mile thick wedges of rock are continuously grinding against each other creating massive energy and heat.

Great pressure accumulates here which occasionally leads to energy waves or 'shock waves' that travel upwards through the 'mantle' of the Earth and are evidenced where we are as ground vibrations. Damage can occur along theses tectonic plate boundaries or along geological fault lines and these are known as 'zones of weakness'.

The originating point of this energy is known as the focus or 'hypocenter'. Directly above this at ground level will be the theoretical centre point of the quake, a phrase nearly everyone is familiar with - the 'epicentre'.

Any civilization located near the epicentre of an earthquake will experience shaking and movement of the surface and depending on the severity of the energy may face catastrophic levels of damage and destruction.

If this epicentre occurred out at sea sometimes the displacement of the seabed can lead to formation of a tidal wave or 'Tsunami' - meaning harbour wave in Japanese. The 2004 Indian Ocean earthquake led to the creation of waves that caused massive devastation when it reached shorelines in Indonesia, Thailand and Sri Lanka.

Earthquakes have traditionally been measured using a seismometer or seismograph. Most people have probably heard of the Richter scale as a way of ascertaining the magnitude of the force involved. "3" on this scale generally denotes small occurrences and over "7" on the scale would indicate a serious and damaging event with potentially significant loss of life.