Beginning of Essay
An earthquake is shaking or trembling of the earth that is volcanic or tectonic in origin. "A broadly satisfying explanation of the majority of can be given in terms of what is called plate tectonics. The basic idea is that the Earth's outermost part also called ....

Middle of Essay
.... what actually causes is tectonic plates which on average move only two inches per year they are driven by convection currents which is the upward movement of heated particles rising from the earth's molten core. As the plates are driven against each other one will try to and eventually will slip underneath the other. When plates move quickly an earthquake is the result. Before the availability of instruments capable of a quantitative measure of their magnitude, were classified according to their intensity. In 1931 a seismologist came up with twelve degrees of intensity ranging from I (felt only by a few) to XII (total damage) this was called a ....