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Why do earthquakes happen?
asked Aug 11, 2010 by triuser (1,775 points)

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Earthquake is the earth, is the vibration of the earth's surface. Vibration of the earth's surface caused by many reasons, can be man-made causes, such as explosions, fire, mechanical vibration, etc.; the same can also be natural causes, such as tectonic earthquakes, volcanic earthquakes, collapse and earthquake.
According to the different causes of earthquakes, we can be divided into five seismic:
1. Tectonic earthquakes: tectonic earthquake because it is underground rock by the role of stress, when stress suffered too much, can not afford to rock occurs when a sudden, quick break or dislocation, fracture or dislocation when the rock will inspire a kind of spread to the surrounding land seismic waves, the local shock wave reached the surface, they will lead to ground vibration. 85% -90%, the world's earthquakes, and all major disasters caused by earthquakes are tectonic earthquakes.
2. Volcanic earthquakes: earthquakes caused by volcanic eruptions since.
3. Reservoir Earthquake: As the reservoir water storage, water distribution reservoir induced earthquake.
4. The fall of the earthquake: Since the fall of ground caused by earthquakes.
5. Artificial earthquake: As the nuclear explosions, fire and other human activities caused by the earthquake
Most earthquakes occur in the most rigid part of the Earth - the edge of the crust and upper mantle rocks inside. Where the role of rock under stress rupture. Became the source of this rupture, shock from here.
answered Aug 11, 2010 by trianswer (22,754 points)