Recently, we've talked about the inner layers of the Earth and that scientists believe that there is a solid core surrounded by a liquid outer core. We also know that the solid crust sits on top of a semi-liquid layer called the asthenosphere which allows the tectonic plates to move and shift over time. This shifting of tectonic plates is responsible for earthquakes, many volcanoes, and the formation of mountain chains. But how do scientists know about the middle of the Earth when we have only traveled a few miles below the surface?
Go to the following website: Seismic Waves
Read the page and go through the activity, answering the questions and checking your answers.
Write a short (a couple of sentences) explanation of how scientists know about the layers of the Earth.