Question

question 29
2 pts
what is the minimum number of seismic stations needed to locate an earthquake?
three
one
two
four

Explanation:

To locate an earthquake's epicenter, the method of triangulation is used. Each seismic station can determine the distance from the station to the epicenter (using the time - difference between P - waves and S - waves). With one station, we only know the distance (a circle of possible locations). With two stations, we get two circles which can intersect at two points. But with three stations, the three circles (from three different stations' distance measurements) will intersect at a single point (the epicenter).

Answer:

three