An earthquake is a phenomenon that results from and is powered by the sudden release of stored energy that radiates seismic waves. At the Earth's surface,

earthquakes may manifest themselves by a shaking or displacement of the ground and sometimes tsunamis, which may lead to loss of life and destruction of

property.

Earthquakes may occur naturally or as a result of human activities. In its most generic sense, the word earthquake is used to describe any seismic

event—whether a natural phenomenon or an event caused by humans—that generates seismic waves.

Earthquakes occur on a daily basis around the world, most detected only by seismometers and causing no damage. Large earthquakes however can cause

serious destruction and massive loss of life through a variety of agents of damage, including fault rupture, vibratory ground motion, inundation, various kinds

of permanent ground failure, and fire or a release of hazardous materials e.g gas leaks or petrol leaks. In a particular earthquake, any of these agents of

damage can dominate, and historically each has caused major damage and great loss of life; nonetheless, for most earthquakes shaking is the dominant

and most widespread cause of damage. There are four types of seismic waves that are all generated simultaneously and can be felt on the ground.

Responsible for the shaking hazard, they are P-waves, S-waves and two types of surfaces waves.