For our lesson today we were exploring the driving forces behind earthquakes. We talked about the different layers of the earth and how the crust is a very thin layer on the surface. We discussed Pangea and how all the continents used to be connected. We talked about fault lines and how there are different types of plate boundaries. Using their hands as the plates, students acted out the interaction between the plates for transformation, convergent and divergent plate boundaries. Demonstrations included how a fault line builds up pressure which will allow a plate to “slip” which then causes earthquakes. We also demonstrated how buildings can be reinforced to make them stronger and safer when shaking occurs during an earthquake.
For our main activity today, we were investigating S waves and P waves and how fast they travel from an epicenter. We calculated the difference in travel time for the P and S waves and were then able to use a standard curve graph to calculate the distance from the epicenter. Students then used a compass to draw a perfect circle around the city in question to find the location of the epicenter. For our example, we had three cities (Houston, Denver and Chicago) with the circles all overlapping just outside the city of Seattle, our epicenter and origin of the earthquake.
Make sure to talk with your student about earthquake safety and what your plan is in case the next big one hits! After all, here in California we’re living on top of the San Andreas Fault, which is steadily building up pressure. Its always good to be prepared!