Which heat source continues to contribute to earth's internal heat?

Radioactive decay, the heat source continues to contribute to earth's internal heat.

Explanation:

The core of the Earth is still burning and what we see on the outer aspect is the mantle and crust that took millions of years to cool down. If we go deeper towards the core of the Earth, we'll start experiencing the heat that still exists there.

Besides this, there's a radioactive decay of the isotopes generate in the core area that exerted heat to the mantle and crust of the Earth. Thus, in this way the Earth's internal energy sustains and sometimes results in the plate tectonics and other geological processes.

Radioactive decay

Explanation:

By scientific research, it has been proven that approximately half of the earth's total heat is generated from radioactive decay.

It was found that the decay of radioactive isotopes of Uranium 238 (U-238) and Thorium 232 (TH-232) and Potassium (K) produces 20 trillion watts to the amount of heat the earth radiates into space.

Radioactive decay of the above mentioned elements (isotopes) is continuous and this source continues to contribute to the earth's internal heat.

This value is large and in continuous generation and it amounts to approximately half of the total heat of the planet.

The earth itself is no longer as hot as at when formed, however, the continuous cooling of the earth also contributes to the total heat of the earth and this makes up another half of the earth's heat.

Scientists believe that the heat from Earth's cooling is bound to the planet's core, while the heat from radioactive decay is distributed in the crust and mantle layers of the earth (internal heat).

This means that the earth's internal heat is from radioactive decay and this is half of the earth's total heat.