The distribution of earthquakes defines the boundary of which major earth feature?

The distribution of earthquakes outlines the boundaries of the earth's tectonic plates. The crust is broken up into slabs of rock called tectonic plates. There are seven major plates and many smaller ones. The boundaries of these plates, where they interact with each other is marked by earthquake activity. The plates diverge, converge or slide past each other at slow rates. The movement of the plates generates earthquakes. 

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