Final answer:
Each star represents an earthquake epicenter, and the convergence of the circles indicates the likely location of the earthquake's epicenter.
Step-by-step explanation:
Each star on the map represents the location of an earthquake epicenter. The circles drawn by the geologists centered at Portland, Salt Lake City, and Los Angeles are used to determine the location of the epicenter. The convergence of the circles at San Francisco indicates that the epicenter of the earthquake is most likely at that location.