Earthquakes are a compelling subject to students living in Southern California. Students learned more about earthquakes by using Epicenter, an interactive earthquake epicenter finding program. After using a Slinky to learn the difference between P and S waves, students were ready to tests their skills as seismologists. Above left is a seismogram from a seismic station, from which the students determined when the P and S waves arrived. Above right, student recorded their data.

After determining when the P and S waves arrived at the seismic station, students used the information to find the distance from that station to the earthquake's epicenter. Once the distance was determined, the program drew a circle with a radius of that determined distance around the station. Once this process was completed for three stations, the location of the earthquake was easily determined by finding the intersection of the three circles (some of which appear as lines on the Mercator projection base map.) Above right, students did an excellent job of finding the location of an earthquake on the Mid-Atlantic Ridge.

To the left is the screen that students used to create their own earthquakes. They controlled when the earthquake occured, where it occured, and how strong it was.

Above, students compared seismograms taken from different seismic stations. To the left is a seismogram from a station very near the epicenter of the earthquake, and to the right from a station farther away from the earthquake's epicenter.