ABSTRACT
Our planet Earth was created 4.55 billion years ago from condensates in a cosmic gas cloud that was the resultant product of a supernova. The Earth contains four key spheres the atmosphere, hydrosphere, biosphere and the geosphere. An earthquake produces three types of seismic waves: Primary, Secondary and surface waves. Basically the Earth comprises three main concentric shells: crust, mantle and core. The mantle comprises 82% of the earth’s volume and we know from the continuity of S-waves through the mantle that it is solid, although due to the high temperatures the rocks can flow at very slow velocities. The fundamental basis for the theory of plate tectonics is the recognition that the outer layers of the Earth are made up of seven major and numerous minor moving plates. The interactions at the boundaries between lithospheric plates has created the ever-changing landscape of our Earth through the formation of oceans, mountains and volcanoes.
