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How is an earthquake’s location determined?

Seismologists use the difference in arrival time between P and S waves to calculate the distance between the earthquake source and the recording instrument (seismograph).

Seismograph sites need to be on hard rock and well away from traffic and other sources of artificial ground noise. Scientists need recordings from at least three seismographs to accurately locate the depth and magnitude of an earthquake.

For a detailed explanation of how we calculate earthquake locations and magnitudes check out this video: