In this investigation, participants will understand that S and P waves are used to find the epicenter of an earthquake by using seismograph data to triangulate an epicenter. This investigation is considered generally safe to do with students. However, please review it for the specific setting, materials, students, and conventional safety precautions. Investigation Question. How do we determine the epicenter of an earthquake? What to do. Skip to main content. Objective: Students will be able to u nderstand how S and P waves are used to find the epicenter of an earthquake by applying their seismic knowledge and mathematical skills to seismographs in order to triangulate an earthquake epicenter.
Preparation Before going to the classroom, you will need to: Contact the teacher to find out the length of the class period, as well as how many copies of handouts and sets of materials you need to bring. Collect all the materials in the list. Make photocopies of the handouts. Make an overhead copy of each of the handouts. Notify the classroom teacher of technology needs overhead projector. Collect any giveaways for the students, such as earthquake posters or plate tectonic fliers.
Run through the investigation yourself and record the data, just to see how long it takes. Adjust the timing to the class period, remembering that you will need time to introduce the investigation, clean up afterwards, and re-set up for the next class if you are working with more than one class. Safety This investigation is considered generally safe to do with students.
Investigation Question How do we determine the epicenter of an earthquake? What to do 5 minutes Prompt a discussion about earthquakes. Optional: show photos or videos of earthquakes and related damage. See Photos of Earthquakes Be sure to accept as many explanations as you can. Some questions you might use for the discussion are: What do you know about the causes and impacts of Earthquakes? Student responses will vary. What do you know about seismic waves? Have any of you ever experienced an earthquake or know anyone who has?
What did it feel like? Was there an initial quake followed by smaller quakes? When seismic data is collected from at least three different locations, it can be used to determine the epicenter by where it intersects. Every earthquake is recorded on numerous seismographs located in different directions. Each seismograph records the times when the first P waves and second S waves seismic waves arrive. From that information, scientists can determine how fast the waves are traveling.
Knowing this helps them calculate the distance from the epicenter to each seismograph. To determine the direction each wave traveled, scientists draw circles around the seismograph locations. These waves travel at different speeds: P-waves being fastest, S-waves being next fastest, and L-waves the slowest. By knowing the time difference between when any two types of earthquake waves arrive at any particular place you can deduce how far away the earthquake epicenter is.
By contacting other seismographic stations it is possible to determine where the earthquake occurred. In this activity you will use seismographic data and a compass to find the epicenter of an earthquake. P-wave arrival S-wave arrival.
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