How do seismologists locate an earthquake’s epicenter using three seismic stations?

When an earthquake happens, fast P waves arrive before slower S waves. By measuring the time gap between those arrivals at a station, seismologists estimate how far away the quake was. With data from three stations, they draw circles around each station using the calculated distances, and the point where the circles meet is the epicenter. This method has been used for more than a century and remains a core part of earthquake science. More stations improve accuracy and also help estimate the quake’s depth and size.