Final answer:
A minimum of three seismic measurements are required to accurately locate the epicenter of an earthquake using the triangulation method, where the circles from three seismic stations intersect.
Step-by-step explanation:
The minimum number of seismic measurements required to locate the epicenter of an earthquake is at least three. By using three different seismic stations, each can record the time difference between the arrival of the P-waves and the S-waves produced by the earthquake. These time differences can then be used to calculate the distance of each station from the epicenter. When these distances are plotted on a map, the point where the three circles intersect represents the epicenter. This method is known as triangulation. If only one or two measurements are available, the precise location cannot be determined due to the lack of intersections that confirm the exact point.