What is an earthquake?How does it occur?

Answer 1

The earthquake is closely related to volcanic. It is the result from the sudden release of stored energy in the Earth's crust that creates seismic waves.
The earthquake most common earth quake is tectonic earthquake. Plate boundaries lock as the plates move past each other, creating frictional stress.When the frictional stress exceeds a critical value, a sudden failure occurs. When the failure at the fault plane results in a violent displacement of the Earth's crust, the elastic strain energy is released and seismic waves are radiated, thus causing an earthquake.

Answer 2

an earthquake is the movement of tectonic plates that make up the earth's crust this occurs naturally and cannot be stopped. the theroey of SOUND waves became obsolete years ago when it was put to the test however there is found to be a shockwave some times where an earthquake occurs depending on how big can affect the world the Epicentre [where the earthquake occurs] that is the strongest point however the shockwaves can travel everywhere. in fact it is even believed that some stars [planets] in our universe have been destroyed by earthquakes due to having stronger gravity pull than earth tectonic movement is believed to be lnked with the tide and so THE MOON so if this thereoy is correct then earthquakes are caused by the moon!

Answer 3

Wow! What a big question! The simple answer is that an earthquake is movement within the Earth. They occur by the buildup of stress in the shallow or deep (but not the middle) crust, along with the sudden release of that stress. However! (there always has to be a however) there are some earthquakes that occur deep within the mantle. Whereas the shallow and deep crust are thought to be rigid, the mantle is thought to be plastic and capable of movement. What causes these earthquakes is a mystery. I have heard that it may have to do with mineral re-assemblages of subducting oceanic crust due to the increased temperature and pressure at the 440 km discontinuity where olivine assumes the perskovite structure. The decreased volume and subsequent collapse of the local mantle could cause an earthquake. Be advised that there are areas of geology that geologists do not fully understand.

Answer 4

Earthquake comes from the Greek word "Seismo" which means to shake. These occur at the edges of plate margins where denser oceanic crust of Iron (Fe) and Magnesium (Mg), "subducts" that is eaten up by the inner earth, where temperatures reach 1000 degrees celcius. 3 types of wave are given out from the energy released by the movement along the fault planes that occur at the edge of these plates. Primary or p waves, secondary or s waves and the waves responsibile for the shaking are the L waves and these are your surface waves. P and S waves travel through the interior of the earth. However only P waves can travel through both liquid and solid matter within the earth. S waves cannot and are therefore refracted and reflected away from their shadow zone within the earth which occurs 115 degrees. These waves are monitored and recorded by a seismometer.

for example the most famous fault everybody has heard about is called San Andreas Fault, located in Southern California. Here Oceanic crust from the Pacific plate meets the thicker continental crust of the North American plate. Oceanic crust always subducts due to being so dense. This action gives rise to shallow, medium and deep focus earthquakes. The point where the movement has occurred is where you will locate your epicentre of the earthquake. As the shaking occurs debris of rocks falls down the continental shelf and displaces the water giving rise to tsynami waves like that you saw on Boxing Day 2004 in South East Asia. Geologists use two scales to measure Earthquakes. Richter Scale the more commonly known one and the other is Mercalli.

Answer 5

The earth has a liquid outer core and the crust is a series of plates 'floating' on the outer core. As the plates either colide there is an earthquake, and or valcanoes. the plates could slide past each other to cause an earthquake. even though the plates relatively only move 2-3 mm a year there comes a time when the tension between the plates is too much and an earthquake appears when the land is reliving that pressure.

Answer 6

An earthquake is the result from the sudden release of stored energy in the Earth's crust that creates seismic waves.

At the Earth's surface, earthquakes may manifest themselves by a shaking or displacement of the ground. Sometimes, they cause tsunamis, which may lead to loss of life and destruction of property. An earthquake is caused by tectonic plates getting stuck and putting a strain on the ground. The strain becomes so great that rocks give way by breaking and sliding along fault planes.

Earthquakes may occur naturally or as a result of human activities. Smaller earthquakes can also be caused by volcanic activity, landslides, mine blasts, and nuclear tests. 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.

An earthquake's point of initial ground rupture is called its focus or hypocenter. The term epicenter means the point at ground level directly above this.


For more go to: http://en.wikipedia.org/wiki/Earthquake

Answer 7

an earthquake is when waves pass through the layers of the earth. Earthquakes are caused by the tectonic plates, that make up the earth's surface, sliding past each other causing friction and sometimes destruction of each other. The movement of the tectonic plates causes seismic waves (P waves and S waves) to be produced which move through the mantle and (P waves only) through the outer and inner cores of the earth...this means that some waves can be sensed at the other end of the earth from the earthquake :)

Answer 8

Earthquake, shaking of the Earth’s surface caused by rapid movement of the Earth’s rocky outer layer. Earthquakes occur when energy stored within the Earth, usually in the form of strain in rocks, suddenly releases. This energy is transmitted to the surface of the Earth by earthquake waves.

Most earthquakes are caused by the sudden slip along geologic faults. The faults slip because of movement of the Earth’s tectonic plates. This concept is called the elastic rebound theory. The rocky tectonic plates move very slowly, floating on top of a weaker rocky layer. As the plates collide with each other or slide past each other, pressure builds up within the rocky crust. Earthquakes occur when pressure within the crust increases slowly over hundreds of years and finally exceeds the strength of the rocks. Earthquakes also occur when human activities, such as the filling of reservoirs, increase stress in the Earth’s crust.

Answer 9

An earthquake is when two plates that are next to each other begin to move. This causes the land to rub against, rise up, or sink below the other. The resulting motion causes earthquakes. Even a little movement will cause earthquakes.

Answer 10

Earthquakes occur when plates push against each other or move further apart.
The centre of the earthquake is called the epicentre. In an earthquake three types of waves the P wave the S wave and the surface waves there are two types of surface wave there is the love wave and the roll wave.