Traveling Sound

Seismology works well because the Earth’s crust has many layers with different thicknesses and densities. When energy from the surface, such as an explosion, strikes the layers beneath, part of the energy travels through the layers of earth’s crust, and part of it is reflected back to the surface. It is similar to bouncing a rubber ball. If the ball is dropped on a concrete sidewalk, its bounce will be quite different than if dropped on a pile of sand. Similarly, each different layer in the Earth “bounces” seismic energy back to the surface with its own particular characteristics.

Seismology uses sound waves and has many uses, including detect petroleum underground, which this video explains.

In this eighth grade science lesson, Traveling Sound, students have the opportunity to conduct two separate experiments, giving them a visual understanding of how sound waves and seismology work.