How do scientists determine where an earthquake starts?

Scientists determine it by calculating the distance of the earthquake's epicenter from the seismometer.

Seismologists use the difference in arrival time between P and S waves to calculate the distance between the earthquake source and the seismograph. Seismograph should be placed far from shaky places like traffic or lose surfaces. It must be placed on a hard rock where there is no disturbance of any kind.

coconut why: has water in it : )