Here's why:
* Seismic waves travel at different speeds through different materials. Solid rock transmits seismic waves faster than liquid rock.
* Seismic waves change direction (refract) when they encounter a boundary between different materials.
* By analyzing the travel times and paths of seismic waves from earthquakes, scientists can map out the different layers of Earth.
This led to the discovery of the following layers:
* Crust: The outermost layer, relatively thin and composed of solid rock.
* Mantle: A thick layer of mostly solid rock, but with a partially molten upper layer.
* Outer Core: A liquid layer of iron and nickel.
* Inner Core: A solid ball of iron and nickel, despite the intense heat and pressure.
The study of seismic waves, particularly from earthquakes, has been instrumental in understanding the internal structure and composition of our planet.
