Earthquake on the Playground
Grade Level: 7-12
Push away from those paper seismograms and get outside to make your own earthquake
waves! You're going to learn about earthquake location kinesthetically. In the
activity below, you will model how earthquake waves travel through the Earth
at different speeds. You also will construct and utilize a graph to characterize
the relationship between distance and time of travel of seismic waves (a travel-time
curve). Finally, you'll use the constructed travel-time curves to locate the
epicenter of a simulated earthquake by triangulation.
While seismologists conduct much of their research indoors at a computer
terminal, going outside to collect data is a vital aspect of their work,
as in the activity below. Seismologists travel to some of the most remote
places on Earth to install seismographs far away from the vibrations of
human civilization. Here they can record the high-quality data necessary
for them to conduct their research, including locating earthquakes.
- 3 stopwatches
- Paper and pens
- Outside, simulate P and S waves by jogging (to model the faster "primary
waves") and walking (to model the slower "secondary waves").
Practice jogging and walking at a constant velocity to ensure consistency.
- To determine the velocity of student P and S waves, station timers (students
using stopwatches) at distances 10, 20 and 30 meters from the source. Time
how long it takes these students, traveling a straight path, to arrive at
timers. To improve the accuracy of the P and S wave velocity measurements,
complete several trials. Write down your findings.
- Compute average travel times for the student P and S waves at various distances,
and graph the data. Like the travel-time curve traditionally found in a standard
earthquake location exercise, you can plot travel times for each wave versus
distance. By plotting how long it takes seismic waves to travel various distances,
you're modeling the way scientists create travel-time curves.
- Next, mark the corners of a 30-meter-square space as well as the "epicenter,"
the place within that square that will be the source of student P and S waves.
Create "seismic stations" by having students with stopwatches standing,
backs to the center, at three corners of the square.
- Assemble six student P and S waves at the epicenter marker, with S waves
standing back-to-back and their associated P waves standing directly in front
of each of them. Until the earthquake occurs, they represent stored potential
energy in rocks.
- Representing an earthquake, have students jog and walk outward from the
epicenter toward the seismic stations. Because student seismometers have their
backs to the epicenter, they register P wave arrival by starting their stopwatches,
and they register S waves by stopping the stopwatches. Record the time differences
between P and S wave arrivals.
- Use this measurement along with the travel time curves they created earlier
to calculate the distance from each station to the epicenter, then combine
all three distances to locate the epicenter by triangulation.
- Once you've calculated the location of the playground earthquake, compare
your result with the actual epicenter in the 30-meter-square space. Discuss
possible reasons for any inaccuracies in determining actual earthquake location.
For the complete activity, please see
For information on seismology careers, visit
For seismology education resources, see