In areas of the Earth’s crust there are places where there is a weakness. In these regions, the crust has not settled down firmly, and there is a break in the rocks, known as a fault. Here rock masses rub against each other with great force and friction.
The energy from this rubbing is changed into vibration in the rock and to the surface. This vibration is an earthquake. The earthquake is the strongest right along the line of fault. This part is called the epicenter of the earthquake. If this is near a habitation, it brings about a great loss of life and property. The whole region gets devastated. Japan is the most earthquake-prone region of the world. Next comes the Mediterranean region.
Below Earthquake info from Wikipedia (Read More):-
An earthquake (also known as a tremor or temblor) is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are recorded with a seismometer, also known as a seismograph. The moment magnitude of an earthquake is conventionally reported, or the related and mostly obsolete Richter magnitude, with magnitude 3 or lower earthquakes being mostly imperceptible and magnitude 7 causing serious damage over large areas. Intensity of shaking is measured on the modified Mercalli scale.
http://en.wikipedia.org/wiki/Earthquake
