Seismic waves are produced in the Earth’s crust when large-scale events take place. For example, earthquakes and volcanic eruptions. These waves then spread in all directions through the layers of Earth, often causing damage to structures on the surface of the Earth.
There are two types of seismic waves:
Both p-waves and s-waves are refracted at the boundaries between the different layers. This is because the layers have different densities. Keep in mind, that refraction is when waves change direction as they pass from one medium to another.
By studying how seismic waves travel, scientists can map out the internal structure of the Earth. This helps us understand what Earth is made up of, as these features are not directly observable.
Seismologists use seismometers to detect the waves, and by observing these readings, it is possible to measure the depth of the Earth’s layers. This is because they can calculate how long it takes the seismic waves to travel from the earthquake site to different areas on Earth.