# Direct and indirect sources of Earth’s interior Upsc

## Sources of Information about Earth’s Interior

The Earth has a radius of 6370 km. It is practically impossible to reach the center of the Earth and research on it.

Due to this scientists and engineers are collecting information on the Interior of Earth based on the estimates and inferences from various sources arising from the earth.

These estimations are classified as Direct Sources and Indirect Sources.

### Direct Sources

The easily available solid earth materials are surface rocks. There are several deep mining has deep. Deep drilling projects such as the “Deep Ocean Drilling Project” and Integrated Ocean Drilling Project” have to give tons of information about the Interior of the earth.

Volcanic eruptions also provided, great information about the interiors. Magma is used for lab analysis. But it is hard to ascertain the depth of the source of such magma.

Deepest Drilled Work

The deepest drill is at Kola, in the Arctic Ocean and the depth is about 12 km.

### Indirect Sources

There are also some indirect sources from which we can get information about the interior of the earth. The temperature and pressure increase with increasing distance from the surface towards the interior in deeper depths.

Also, the density of the material also increases with depth. As the thickness of the earth is already known, a scientist has roughly estimated the value of temperature, pressure, and density of materials at varying depths.

By using Meteors, which come from outside the earth used to estimate the interior of the earth. Even though these materials come out of the earth, it is important to note that these things are made up of things that are similar to the ones we find on the earth.

The other indirect sources are Gravitation, Magnetic field, and seismic activities.

Gravitation – Gravitation force (g), which is not equal everywhere. It is greater near the poles and less at the equator.

This is because the equator is from a greater distance away from the center of the earth than the poles.

Also, the gravity values change with the mass of material, the uneven distribution of mass of materials inside the earth influences this value.

Gravity force(g), value change from place to place. This is called Gravity Anomaly. Gravity Anomaly provides us with the value of the distribution of mass of the material in the crust of the earth.

Also, magnetic surveys give us the data about the distribution of magnetic materials in the crustal portion and thereby give information about the distribution of materials in this region.

Also, seismic activities are also important sources to get information regarding the interiors of the earth.

* * All the Notes in this blog, are referred from Tamil Nadu State Board Books and Samacheer Kalvi Books. Kindly check with the original Tamil Nadu state board books and Ncert Books.