Radioactive Decay Powers Earth's Interior

About half of Earth's internal heat comes not from residual warmth left over from the planet's formation but from ongoing radioactive decay in the crust and mantle. Uranium-238, uranium-235, thorium-232, and potassium-40 produce most of this radiogenic heat as they decay. Scientists estimate Earth's total internal heat flow at about 47 terawatts. This energy drives mantle convection, plate tectonics, mountain building, metamorphism, and volcanism, while core convection helps sustain Earth's magnetic field.

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