Temperature inside Earth

Introduction

The Earth comprises three layers, the crust, the mantle and the core. Molten lava lies in the deepest layers of the ground, and its temperature resembles that of the Sun. Earth’s internal temperature increases with its depth and is approximately 600 °C. It was previously estimated as 5000 °C. This shift in temperature remains unclear, although a vertical progression is observed.

It is essential to understand the division of the Earth’s layers for knowing the shift in the pressure and temperature of the Earth’s core. The Earth is divided into three layers, based on the planet’s mechanical positioning and geological components. 

Layers of Earth

A sliced figure of the Earth reveals its three main layers: crust, mantle, and core.

1. Crust: The crust comprises 1% of the Earth’s mass. The two types mainly include Continental crust and Oceanic crust. 
2. Mantle: The second layer comprises approximately 68% of the Earth’s mass.
3. Core: The core is the final layer of the Earth, covering the remaining 31% mass. 

Temperature inside Earth’s Three Layers

• Crust

The crust is the topmost surface of the Earth and lies above the mantle. The density and peridotite tendencies of the mantle enable a stable layer of the crust on the mantle. The thickness of the crust varies from 15 km to 20 km and differs with each geological positioning. Moreover, the temperature of Earth’s crust is subject to change based on natural and human activities. The thin crust is the bedrock of human civilization. It enables a natural ecosystem, but the surface is just a part of the crust, which goes further beyond the realms of exploration.

The Temperature of the Crust 

The temperature inside the Earth is subjected to dramatic shifts from one layer to the other. It remains stable at 14 °C within the first few kilometres of intervention. The crust begins to warm up in the inner layers and attains a temperature of 100 °C in rapid progression. This temperature increases by approximately 30 °C for every kilometre. The final temperature where the crust and mantle meet is 1000 °C. 

• Mantle

The mantle is the middle and widest layer of the Earth with a thickness of 2900 km. It is sandwiched between the crust and core. The mantle is mostly solid, with partial fluid floating across the layer sections. It is made up of molten material separated from iron and nickel during the Earth’s formation. 

The Temperature of the Mantle 

The temperature of the mantle ranges from 1000 °C to 4000 °C, and that at the crust-mantle boundary increases due to the inclusion of geothermal gradients in the atmosphere. The increased temperature builds up pressure in the middle layer, solidifying most rocks. 

• Core

The core is the deepest layer and the centremost point of the Earth, with a radius of approximately 1220 km. The core majorly comprises an alloy of iron and nickel and a mixture of other elements. 

The Temperature of the Core

The core temperature is estimated to be approximately 5700 °C to 6000 °C. This value has often been challenged, with estimations as high as 6230 °C. The temperature is highest at the Earth’s core. 

Temperature Estimation of the Earth’s Core

The approximate temperature of the core is obtained by subjecting impure iron to the inner core pressure and evaluating its melting temperature. Thus, the iron solidifies at a higher temperature due to the subsequent increase in pressure. 

The Non-linear Increase in Earth’s Temperature

Earth’s temperature gradually increases with its depth. The temperature increases within the first 100 km by approximately 15 °C to 30 °C/km. Soon after, the temperature falls dramatically and increases only near the mantle due to the diverse tectonic settings of the lithosphere. The temperature gradient found in the central parts of the continents is lower than the subduction zones, altering the pattern of temperature increase through the first 100 km of the Earth’s interior. 

Conclusion

The temperature of the Earth’s interior increases with its depth. Although the increase is gradual, it is non-linear. The planetary progression of millions of years is entrapped in the Earth’s layers. The entrapped heat from the friction of tectonic plates and the burning furnace of radioactive elements leads to a higher temperature (6000 °C). We can estimate the heat of our planet through the complimentary study of heat flow caused by seismic waves. The heat and pressure at the Earth’s core melts the rocks into a wax-like figure, which solidifies to the planet’s.