Back in the heady days of my youth "epicentre" was a geological term referring to the point on the surface above where an earthquake starts, and that's all it was.
I miss those days.
The Random House Dictionary defines it as: "A point, directly above the true center of disturbance, from which the shock waves of an earthquake apparently radiate."
(The Random House Dictionary of the English Language, The Unabridged Edition, c. 1983, and for the record, also 1981,1979,1973,1971, 1970, 1969, 1967, and 1966.)
It is the only definition offered.
I wish it had stayed that way.
Today, online dictionaries offer a second, common use definition of it where it is used to mean center.
It makes my soul hurt.
The prefix 'epi' is used in words borrowed from Greek and means upon, on, over, near, at, before and after. I suspect "epi" is tacked on these days as a simple modifier of center as if in some way it makes the word bigger, stronger, and more important.
Like the hard copy dictionary I consulted today, I come from a time where access was not a verb, there was no reverse engineered verb root of liaison, and literally meant literally.
Language evolves, and its a good thing, but I refuse to always evolve with it.