What is Earth Quake?

An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth, resulting from the sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in size from those that are so weak that they cannot be felt to those violent enough to toss people around and destroy whole cities. The seismicity or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time.

An earthquake is a shaking of the ground caused by the sudden breaking and movement of large sections (tectonic plates) of the earth's rocky outermost crust. The edges of the tectonic plates are marked by faults (or fractures). Most earthquakes occur along the fault lines when the plates slide past each other or collide against each other.The shifting masses send out shock waves that may be powerful enough to 

• alter the surface of the Earth, thrusting up cliffs and opening great cracks in the ground and
• cause great damage ... collapse of buildings and other man-made structures, broken power and gas lines (and the consequent fire), landslides, snow avalanches, tsunamis (giant sea waves) and volcanic eruptions.

Fault or fault plane = the surface where when two blocks of the earth suddenly slip past one anotherHypocenter = the location below the earth’s surface where the earthquake startsEpicenter = the location on the surface of the earth directly above the hypocente

it`s the moving of Rocks or plates under the ground causes earthquake 

Earthquake is a result of the movement of the upper mantle layer, which is layer of the earth, which is responsible for earthquake and volcanoes. It consists of basic and ultra basic rocks , liquid and semi-moving. The earth's crust moves to from earthquake,volcanoes, folds,faults and mountains.

sudden shaking of earth is known to be an earthquake

 

As a seismic waves releases from epicenter different types of waves are propagated from center and moves outwards, primary and secondary waves are the fasted waves which travel inside of earth structure and love and Rayleigh waves are the  destructive waves which moves/ passes on the earth surface and cause destruction by shaking the ground in to and fro or by swinging of ground motion.

An earthquake is the sudden, rapid shaking or rolling of the Earth. Earthquakes happen when rocks break or slip along fault lines in the Earth’s crust, releasing energy that causes the ground to move.