Epicenter (or epicentre, as it’s spelled outside the U.S.) originally referred to the point of the earth’s surface above the center of an earthquake. Extending from this definition, the word has also come to refer to the center of any negative or dangerous event. This newer sense of epicenter is useful, as there are few alternatives that carry the same meaning.
But the word is perhaps overextended when writers do away with the negative connotations and use epicenter as merely a synonym of center. In such cases, there’s no reason not to use center. Trying to confine epicenter to its old use might be a losing battle, though, as the word is now very common in the new use.
In these instances, center (or centre) would work just as well:
Marc Wanamaker, a Los Angeles historian and expert on Hollywood history, tells us how Hollywood became the epicenter of the film industry. [ABC 7]
Boasting the UK’s largest Korean community, New Malden – and Burlington Road in particular – is the epicentre of Korean food in the UK. [Guardian]
And if there’s an epicentre of the puppet scene these days, it’s in an industrial park just off the Macleod Trail. [Calgary Herald]
In contrast, these writers use epicenter in its older sense:
He maintained that Greece, the epicenter of the crisis, would remain in the single currency zone. [CNN]
Track damage from the Hector Mine earthquake was all within 20 km of theepicenter and included buckled track, other disturbances to track alignment and surface and displacement of ballast from cribs. [Advancing Mitigation Technologies and Disaster Response for Lifeline Systems, James E. Beavers]
[T]he spatial distribution of infested trees became contagious, possibly due to temporal changes in location of the attack epicenter within the stand. [Population Ecology]