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An earthquake centroid is an effective average location of seismic moment release. It differs from the hypocenter, where rupture starts, and can depend on the source representation and observations. An associated centroid time similarly averages release rather than marking its first instant.

The hypocentre is the point where rupture begins. The epicentre is its projection onto the Earth's surface. An earthquake centroid is an effective spatial average of moment release over the rupture, with a corresponding mean release time. Initiation and average release need not occur at the same place or time, especially for an extended, asymmetric rupture.