This week students became seismologists, studying the origin, nature, and effects of earthquakes.
We started the class by asking students if they had experienced an earthquake before, what did it feel like, and what they thought caused this shaking. Some students offered examples and instances when they had experienced earthquakes and their knowledge about how earthquakes are generated. Some students remembered the earthquake in 2012 (in Maine) that was felt in Massachusetts!
With this primer to our discussion, we reviewed the structure of the earth’s interior, its layers, and the tectonic plates that form its outer layer. Next, we introduced how these tectonic plates moved at plate boundaries. The students learned about three different ways plates could move at boundaries and how each different movement may result in the formation of new geologic structures. We noted examples of where plates have converged to form mountains (the Himalayas), where plates have diverged to form new ocean crust (the Atlantic Ocean), and where plates slide past one another (transform fault – San Andreas fault in California).
We next introduced the idea that earthquakes result from the release of tension between plates that move past one another at plate boundaries. Students understood the concept that rough surfaces of the tectonic plates tend to snag and get caught on other tectonic plates. These “snags” allow for a build-up in tension within interacting plates, that when finally released, results in an earthquake.
Following this, we discussed the damage that quakes can cause, why some regions are more likely to have earthquakes than others, and how quake-prone regions of the world have laws that dictate how buildings can be made earthquake-proof.
After our initial discussion, students worked through three workstations designed to cement the following concepts: 1) how plate boundaries relate to the number of earthquakes in an area, 2) how structural integrity is needed for buildings to help survive a quake and 3) how the plates slide past each other. At the end of these activities, students were asked to share their observations. For workstation 1, students analyzed maps of plate boundaries and earthquake locations. Here, they observed that earthquakes were prevalent in areas of convergent plate boundaries – in regions near South America and Asia, although this trend in earthquakes and plate boundaries was not the same for other regions of the world. For workstation 2, students noticed that building structures that had supportive cross braces withstood earthquake testing. For workstation 3, students observed that tension/friction builds up between two plates, sliding past one another.