How do earthquake scientists locate the epicenter of a quake?
Quick Answer
They compare the arrival times of P waves and S waves at several seismograph stations. The time gap tells them how far away the quake was, and three or more stations can pinpoint the epicenter.
The Full Story
Seismologists locate an earthquake by measuring when the first P waves and slower S waves reach different stations. The larger the time gap between those arrivals, the farther the station is from the quake. By drawing circles around several stations using those distances, they can find the point where the circles intersect. That point is the epicenter, directly above the earthquake’s focus underground. Modern networks use digital seismometers and computers, but the basic triangulation method has been used for more than a century.
Key Facts
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Suggested video title for this topic:
"How a quake’s first wiggles reveal exactly where it struck"
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