The number of seismic stations needed to locate an earthquake’s epicenter depends on the size of the earthquake. For small earthquakes, one or two stations may be enough to locate the center of the event. For larger earthquakes, more stations are required to accurately locate the event center.
The reason for this is that seismic waves travel at different speeds through different types of rock. By measuring how long it took for seismic waves to reach various seismograph stations, seismologists can calculate how far away each station is from the earthquake’s epicenter.
The first step in locating an earthquake’s epicenter is finding out how far away each station is from the epicenter. This can be done by comparing arrival times of P waves and S waves at each station. P waves arrive first because they travel faster than S waves through solid rock (about 5 miles per second) and slower through liquids (2 miles per second).
Knowing this information allows seismologists to determine how far away each station is from the epicenter using a simple trigonometric formula called triangulation.
After determining how far away each station is from the epicenter, seismologists then use those distances along with information about how long it took for seismic waves to travel between each pair of stations
Last modified: July 31, 2022