Explain how scientists used naturally-occurring waves to provide evidence that the earth has a molten outer co?

They use earthquake waves. There are two main types P waves and S waves. The S waves cannot travel through liquids while P waves can. The S waves bounce back, and scientists can detect where the S waves bounce back from. And they can detect bouncing back from both bodies of water as well as liquids deed in the earth's interior, and they can deduce from that that the earth has a molten outer core