EARTHQUAKES THE DESTROYER

Earthquakes are the Earth''s natural means of releasing stress. When the Earth''s plates move against each other, stress is put on the lithosphere. When this stress is great enough, the lithosphere breaks or shifts. Imagine holding a pencil horizontally. If you were to apply a force to both ends of the pencil by pushing down on them, you would see the pencil bend. After enough force was applied, the pencil would break in the middle, releasing the stress you have put on it. The Earth''s crust acts in the same way. As the plates move they put forces on themselves and each other. When the force is large enough, the crust is forced to break. When the break occurs, the stress is released as energy which moves through the Earth in the form of waves, which we feel and call an earthquake.
There are many different types of earthquakes: tectonic, volcanic, and explosion. The type of Earthquake depends on the region where it occurs and the geological make-up of that region. The most common are tectonic earthquakes. These occur when rocks in the earth''s crust break due to geological forces created by movement of tectonic plates. Another type,volcanic earthquakes, occur in conjunction with volcanic activity. Collapse Earthquakes are small earthquakes in underground caverns and mines, and explosion earthquakes result from the explosion of nuclear and chemical devices. We can measure motion from large tectonic earthquakes using GPS because rocks on either side of a fault are offset during this type of earthquake.