Q. How many seismic stations are required to locate the epicentre of an earthquake?
Answer: 3
Notes: The point within the earth where the actual movement takes place is called the focus. The point on the surface directly above the focus is called the epicenter. At least three seismic stations are needed to find the earthquake epicenter. A single recording station can only calculate distance, but not direction; to cover all possibilities, a complete circle is drawn around that station. If only two earthquake recording stations are used, the circles will overlap at two points. Data from a third recording station will eliminate one of these points.