What is an Earthquake and what are the different types?.
An earthquake is the motion of the earth's crust, which can be caused by transforming, diverging or converging plates. (1) Each type of boundary produces a certain earthquake depth, focus and epicenter. When two or more plates collide, rub, or separate, tension is being to build from this movement. As this tension builds, the rock will eventually reach a frictional peak where it will no longer be able to withstand the pressure and release's it in the form of seismic waves. These waves are what make earthquakes so destructive. Generally, we devise these waves as either "primary" or "secondary" waves. The primary waves travel through all of the earth and the secondary wave's travel through the solids of the earth but not liquids. These are the waves that scientist use to track earthquakes and study them. There is also something called a diverging plate boundary (2) where two plates are being separated by the convection zones in the earth's mantle. These convection zones cause the mantle to circulate and apply tensional forces to plates. Usually diverging plate boundaries happen on the ocean floor. An example of this type of boundary is the Mid-Atlantic Ridge. As the plates separate new crust in being formed from the uprising magma. As the magma rises, it causes what we know as sea floor spreading and a valley like crack is made at the divergent boundary. How does this relate to earthquakes? Well as the plates move apart normal faulting occurs along the ridge. This faulting eventually starts to build up tension and therefore the oceanic crust or continental plate will start to fracture and cause earthquakes. These earthquakes are relatively small in magnitude and intensity since the tension is built up all along the boundary and not necessarily at one particular spot. This in turn means that the frequency of these earthquakes is rather large, but since they are shallow and small, they do not cause extensive damage to people and/or land property.