How Could Someone Predict The Approximate Location Of An Epicenter Without A Seismograph

How could someone predict the approximate location of an epicenter without a seismograph

 

You can use a map and draw three circles using a compass and wherever they intersect is where the epicenter is. You draw the 3 circles by knowing the difference in arrival times of the P and S-waves (the seismic waves produced by earthquakes). 

The greater the difference in arrival times, the farther that location is from the epicenter.