An epicenter is the point on Earth's surface directly above where an earthquake begins underground. When an earthquake strikes, the actual breaking and shifting of rock happens deep beneath the surface at a spot called the focus or hypocenter. The epicenter is the location straight up from that underground rupture, marked on maps as the earthquake's center.

Seismologists (scientists who study earthquakes) carefully track epicenters because they help identify which areas suffered the strongest shaking and need the most help. A town located near the epicenter typically experiences much more violent shaking than a city hundreds of miles away. When news reports say “the epicenter was 50 miles off the coast” or “the epicenter was near Los Angeles,” they're pinpointing where the earthquake started and where the shaking was strongest at ground level.

People now use epicenter more broadly to mean the center or focal point of any significant event or situation. You might hear someone say “that school became the epicenter of a scandal” or “the gymnasium was the epicenter of excitement during the championship game.” In these cases, epicenter means the place where something important originated or where activity was most concentrated, borrowing from the geological term's sense of a crucial central point.