Earth Science

Geological Activity from Plate Tectonics Processes

Locating Earthquake Epicenters

Study Tip
Three circles drawn from three seismic stations, each with a radius of the distance from the epicenter to the station, can pinpoint where an epicenter is.

Finding the Epicenter

  • A technique called triangulation is employed to find an earthquake’s epicenter.
  • First, the distance of each seismograph from the epicenter is determined by the arrivals of the P-waves and S-waves.
  • After the distances have been recorded, circles are drawn from the seismographs, each with a radius of the distance from the epicenter.
  • All three of the drawn circles should intersect at a certain point, which is the epicenter of the earthquake.
Study Tip
Three circles drawn from three seismic stations, each with a radius of the distance from the epicenter to the station, can pinpoint where an epicenter is.
Study Tip
The same way a person may cast a shadow over another person when they stand under the sun, planets or celestial bodies that have aligned themselves cast shadows over one another as well.
Concept Check
  • Why do you need three seismographs to determine where an epicenter is?
  • Why wouldn’t two seismographs work?
Finding the Epicenter
Concept Check
  • Why do you need three seismographs to determine where an epicenter is?
  • Why wouldn’t two seismographs work?