HUMAN EARTHQUAKE WAVES

Students often have difficulty understanding the difference between P wave and S waves and how some waves travel through liquid and some do not. This activity uses students in a class to demonstrate the properties of these waves.

A group of students - about 10, is lined up. They are asked to overlap legs and arms so they are linked. Another student then pushes on the group and students in the audience notice how the pulse travels trough the students on the line. The length of the student line can be measured and the time it takes for the pulse to travel the line can be measured so velocity can be calculated. A second pulse is sent through the line but this time the student pushes the line forward and back like a transverse wave. The velocity can be calculated for this as well and a difference should be noted. These results can be compared to a seismograph.

Now the students are asked to stand shoulder to shoulder without linking. The compression pulse is sent down the line and students note that the wave travels through. Then the student moves the line forward and back and shows that the pulse does not travel down the line. Why? The teacher asks the students to think about states of matter - which line might be a liquid and which a solid. Once the students recognize the relationship between molecules in a liquid and solid the understanding of why some waves do not travel through a liquid becomes clear.

This has been a very powerful activity in my geology classes. It is alot of fun and makes the learning clear and meaningful.