Assignment task: Using a compass, plot the distance to the epicenter from each station on the map of the western U.S. (page 5) as a circle centered on each station with a radius equal to the distance from the epicenter. The epicenter is the point where all three circles intersect.
Note: Your three circles should intersect at a single point if you made all your measurements carefully. If your circles are not close to intersecting at a single point, redo the measurements and calculations above, starting with more precisely determining the difference in arrival time of P and S waves on the three seismographs.