How do scientists use seismic waves to learn about Earths layers?

Scientists use seismic waves to study Earth's layers by analyzing how they travel through the different materials that make up the Earth. The speed and direction of seismic waves change as they encounter different densities and compositions in the layers of the Earth, providing valuable information about the structure of the planet's interior. By measuring the arrival times and characteristics of seismic waves at different locations, scientists can infer details about the depth, density, and composition of Earth's layers.