Sources of Information for the Study of Earth’s Interior

Direct Sources of information about the Earth’s Interior

1. Deep earth mining and drilling reveal the nature of rocks deep down the surface.
2. But as mining and drilling are not practically possible beyond a certain depth, they don’t reveal much information about the earth’s interior.
3. Mponeng gold mine(deepest mine in the world) and TauTona gold mine(second deepest mine in the world) in South Africa are deepest mines reaching to a depth of only 3.9 km.
4. And the deepest drilling is only about 12 km deep hole bored by the Soviet Union in the 1970s over the Kola Peninsula.
5. Volcanic eruption forms another source of obtaining direct information.

Indirect Sources of information about the Earth’s Interior:

1. By analysing the rate of change of temperature and pressurefrom the surface towards the interior.
2. Meteors, as they belong to the same type of materials earth is made of.
3. Gravitation, which is greater near poles and less at the equator.
4. Gravity anomaly, which is the change in gravity value according to the mass of material, gives us information about the materials in the earth’s interior.
5. Magnetic sources. Magnetic surveys also provide information about the distribution of magnetic materials in the crustal portion, and thus, provide information about the distribution of materials in this part.
6. Seismic Waves: the shadow zones of body waves (Primary and secondary waves) give us information about the state of materials in the interior.