Earthquakes and Tsunami

Earthquakes: 

Plates tecnonics is a scientific theory about the large scale motion of Earth's lithosphere.

http://theorientalhotel.wordpress.com/2010/04/25/thai-tectonic-plates-colliding/

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  The tectonics plates are two types of litosphere: thin oceanic and thicker continental.

  The tectonic plates are able to move due to the Earth's lithosphere has a higher strength and lower density on their mantle. The density variations in the mantle result in movement, and this results in a movement of seafloor away from the spreading ridge to the earth.

  Earthquakes are usually caused when rock underground suddenly breaks along a fault due to the movement os tectonic plates. This sudden release of energy causes the seismic waves that make the ground shake. When two blocks of rock or two plates are rubbing against each other, they stick a little. They don't just slide smoothly; the rocks catch on each other. The rocks are still pushing against each other, but not moving. After a while, the rocks break because of all the pressure that's built up. When the rocks break, the earthquake occurs.

And the tsunamis???

   Tsunami is a series of water waves caused by the displacement of a large volume of a body of water, usually an ocean, but can occur in large lakes. Tsunamis occur because the earthquakes and this form due to the movement of tectonic plates too.

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